closed electron drift: Topics by Science.gov

Pulsed electron beam propagation in gases under pressure of 6.6 kPa in drift tube

NASA Astrophysics Data System (ADS)

Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Poloskov, A. V.

2017-02-01

This paper presents the results of an investigation of pulsed electron beam transport propagated in a drift tube filled with different gases (He, H2, N2, Ar, SF6, and CO2). The total pressure in the drift tube was 6.6 kPa. The experiments were carried out using a TEA-500 pulsed electron accelerator. The electron beam was propagated in the drift tube composed of two sections equipped with reverse current shunts. Under a pressure of 6.6 kPa, the maximum value of the electron beam charge closed on the walls of the drift tube was recorded when the beam was propagated in hydrogen and carbon dioxide. The minimum value of the electron beam charge closed on the walls of the drift tube was recorded for sulfur hexafluoride. The visualization of the pulsed electron beam energy losses onto the walls of the drift chamber was carried out using radiation-sensitive film.
Drive electrostatic plasma oscillations in a closed electron drift accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morozov, A.I.; Nevrovskii, V.A.; Smirnov, V.A.

1973-09-01

The present work describes and experimental investigation of the perturbations created in the plasma of a closed electron drift accelerator (CEDA) by a time-varying potential applied to an electrode in the plasma. In particular, the driven electrostatic oscillations are in phase over the entire volume of the channel and the attenuation of the signal amplitude is sensitive to the direction of the electron flux in the accelerator. Certain aspects of the propagation of the harmonic signals and pulses in the plasma are established. A substantial drop in signal amplitude occurs between the electrode and the plasma. (auth)
Energetic Electron Acceleration, Injection, and Transport in Mercury's Magnetosphere

NASA Astrophysics Data System (ADS)

Dewey, R. M.; Slavin, J. A.; Raines, J. M.; Baker, D. N.; Lawrence, D. J.

2018-05-01

Electrons are accelerated in Mercury’s magnetotail by dipolarization events, flux ropes, and magnetic reconnection directly. Following energization, these electrons are injected close to Mercury where they drift eastward in Shabansky-like orbits.
Van Allen Probes Observations of Radiation Belt Acceleration associated with Solar Wind Shocks

NASA Astrophysics Data System (ADS)

Foster, J. C.; Wygant, J. R.; Baker, D. N.

2017-12-01

During a moderate solar wind shock event on 8 October 2013 the twin Van Allen Probes spacecraft observed the shock-induced electric field in the dayside magnetosphere and the response of the electron populations across a broad range of energies. Whereas other mechanisms populating the radiation belts close to Earth (L 3-5) take place on time scales of months (diffusion) or hours (storm and substorm effects), acceleration during shock events occurs on a much faster ( 1 minute) time scale. During this event the dayside equatorial magnetosphere experienced a strong dusk-dawn/azimuthal component of the electric field of 1 min duration. This shock-induced pulse accelerates radiation belt electrons for the length of time they are exposed to it creating "quasi-periodic pulse-like" enhancements in the relativistic (2 - 6 MeV) electron flux. Electron acceleration occurs on a time scale that is a fraction of their orbital drift period around the Earth. Those electrons whose drift velocity closely matches the azimuthal phase velocity of the shock-induced pulse stay in the accelerating wave as it propagates tailward and receive the largest increase in energy. Relativistic electron gradient drift velocities are energy-dependent, selecting a preferred range of energies (3-4 MeV) for the strongest enhancement. The time scale for shock acceleration is short with respect to the electron drift period ( 5 min), but long with respect to bounce and gyro periodicities. As a result, the third invariant is broken and the affected electron populations are displaced earthward experiencing an adiabatic energy gain. At radial distances tailward of the peak in phase space density, the impulsive inward displacement of the electron population produces a decrease in electron flux and a sequence of gradient drifting "negative holes".Dual spacecraft coverage of the 8 October 2013 event provided a before/after time sequence documenting shock effects.
On the longitudinal distribution of electric field in the acceleration zones of plasma accelerators and thrusters with closed electron drift

NASA Astrophysics Data System (ADS)

Kim, V. P.

2017-04-01

The long-term experience in controlling the electric field distribution in the discharge gaps of plasma accelerators and thrusters with closed electron drift and the key ideas determining the concepts of these devices and tendencies of their development are analyzed. It is shown that an electrostatic mechanism of ion acceleration in plasma by an uncompensated space charge of the cloud of magnetized electrons "kept" to the magnetic field takes place in the acceleration zones and that the electric field distribution can be controlled by varying the magnetic field in the discharge gap. The role played by the space charge makes the mechanism of ion acceleration in this type of thrusters is fundamentally different from the acceleration mechanism operating in purely electrostatic thrusters.
Development of electron beam ion source for nanoprocess using highly charged ions

NASA Astrophysics Data System (ADS)

Sakurai, Makoto; Nakajima, Fumiharu; Fukumoto, Takunori; Nakamura, Nobuyuki; Ohtani, Shunsuke; Mashiko, Shinro; Sakaue, Hiroyuki

2005-07-01

Highly charged ion is useful to produce nanostructure on various materials, and is key tool to realize single ion implantation technique. On such demands for the application to nanotechnology, we have designed an electron bean ion source. The design stresses on the volume of drift tubes where highly charged ions are confined and the efficiency of ion extraction from the drift tube through collector electrode in order to obtain intense ion beam as much as possible. The ion source uses a discrete superconducting magnet cooled by a closed-cycle refrigerator in order to reduce the running costs and to simplify the operating procedures. The electrodes of electron gun, drift tubes, and collector are enclosed in ultrahigh vacuum tube that is inserted into the bore of the magnet system.
Extensive electron transport and energization via multiple, localized dipolarizing flux bundles

NASA Astrophysics Data System (ADS)

Gabrielse, Christine; Angelopoulos, Vassilis; Harris, Camilla; Artemyev, Anton; Kepko, Larry; Runov, Andrei

2017-05-01

Using an analytical model of multiple dipolarizing flux bundles (DFBs) embedded in earthward traveling bursty bulk flows, we demonstrate how equatorially mirroring electrons can travel long distances and gain hundreds of keV from betatron acceleration. The model parameters are constrained by four Time History of Events and Macroscale Interactions during Substorms satellite observations, putting limits on the DFBs' speed, location, and magnetic and electric field magnitudes. We find that the sharp, localized peaks in magnetic field have such strong spatial gradients that energetic electrons ∇B drift in closed paths around the peaks as those peaks travel earthward. This is understood in terms of the third adiabatic invariant, which remains constant when the field changes on timescales longer than the electron's drift timescale: An energetic electron encircles a sharp peak in magnetic field in a closed path subtending an area of approximately constant flux. As the flux bundle magnetic field increases the electron's drift path area shrinks and the electron is prevented from escaping to the ambient plasma sheet, while it continues to gain energy via betatron acceleration. When the flux bundles arrive at and merge with the inner magnetosphere, where the background field is strong, the electrons suddenly gain access to previously closed drift paths around the Earth. DFBs are therefore instrumental in transporting and energizing energetic electrons over long distances along the magnetotail, bringing them to the inner magnetosphere and energizing them by hundreds of keV.Plain Language SummaryScientists have wondered how narrow flow channels in space could transport and energize electrons enough before the electrons escape the channel. They also wondered how narrow, localized magnetic field peaks (and their electric fields) contribute to electron energization in comparison to wide, large-scale electromagnetic fields. We show that it is actually because these fields are so localized that the electrons are transported closer toward Earth. Because of the rules that govern an electron's motion, electrons get trapped circling around the localized magnetic field peak and cannot escape the flow channel. As the peak travels earthward, it takes the electrons along with it and energizes the electrons along the way. When multiple peaks follow each other, they all contribute to a longer energization signature. The magnetic field peaks can also pileup when they hit the strong magnetic field closer to Earth, creating a bigger, longer magnetic field signature. It once again appears that great things come in small packages. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1313556-nonlinear-elm-simulations-based-nonideal-peelingballooning-model-using-bout++-code','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1313556-nonlinear-elm-simulations-based-nonideal-peelingballooning-model-using-bout++-code">Nonlinear ELM simulations based on a nonideal peeling–ballooning model using the BOUT++ code</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Xu, X. Q.; Dudson, B. D.; Snyder, P. B.; ... 2011-09-23 A minimum set of equations based on the peeling–ballooning (P–B) model with nonideal physics effects (diamagnetic drift, E × B drift, resistivity and anomalous electron viscosity) is found to simulate pedestal collapse when using the BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Linear simulations of P–B modes find good agreement in growth rate and mode structure with ELITE calculations. The influence of the E × B drift, diamagnetic drift, resistivity, anomalous electron viscosity, ion viscosity and parallel thermal diffusivity on P–B modes is being studied; we find that (1) the diamagnetic drift and Emore » × B drift stabilize the P–B mode in a manner consistent with theoretical expectations; (2) resistivity destabilizes the P–B mode, leading to resistive P–B mode; (3) anomalous electron and parallel ion viscosities destabilize the P–B mode, leading to a viscous P–B mode; (4) perpendicular ion viscosity and parallel thermal diffusivity stabilize the P–B mode. With addition of the anomalous electron viscosity under the assumption that the anomalous kinematic electron viscosity is comparable to the anomalous electron perpendicular thermal diffusivity, or the Prandtl number is close to unity, it is found from nonlinear simulations using a realistic high Lundquist number that the pedestal collapse is limited to the edge region and the ELM size is about 5–10% of the pedestal stored energy. Furthermore, this is consistent with many observations of large ELMs. The estimated island size is consistent with the size of fast pedestal pressure collapse. In the stable α-zones of ideal P–B modes, nonlinear simulations of viscous ballooning modes or current-diffusive ballooning mode (CDBM) for ITER H-mode scenarios are presented.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhRvS..14f2802R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhRvS..14f2802R">Model-independent and fast determination of optical functions in storage rings via multiturn and closed-orbit data</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Riemann, Bernard; Grete, Patrick; Weis, Thomas 2011-06-01 Multiturn (or turn-by-turn) data acquisition has proven to be a new source of direct measurements for Twiss parameters in storage rings. On the other hand, closed-orbit measurements are a long-known tool for analyzing closed-orbit perturbations with conventional beam position monitor (BPM) systems and are necessarily available at every storage ring. This paper aims at combining the advantages of multiturn measurements and closed-orbit data. We show that only two multiturn BPMs and four correctors in one localized drift space in the storage ring (diagnostic drift) are sufficient for model-independent and absolute measuring of β and φ functions at all BPMs, including the conventional ones, instead of requiring all BPMs being equipped with multiturn electronics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24j3517S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24j3517S">Analytic non-Maxwellian electron velocity distribution function in a Hall discharge plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shagayda, Andrey; Tarasov, Alexey 2017-10-01 The electron velocity distribution function in the low-pressure discharges with the crossed electric and magnetic fields, which occur in magnetrons, plasma accelerators, and Hall thrusters with a closed electron drift, is not Maxwellian. A deviation from equilibrium is caused by a large electron mean free path relative to the Larmor radius and the size of the discharge channel. In this study, we derived in the relaxation approximation the analytical expression of the electron velocity distribution function in a weakly ionized Lorentz plasma with the crossed electric and magnetic fields in the presence of the electron density and temperature gradients in the direction of the electric field. The solution was obtained in the stationary approximation far from boundary surfaces, when diffusion and mobility are determined by the classical effective collision frequency of electrons with ions and atoms. The moments of the distribution function including the average velocity, the stress tensor, and the heat flux were calculated and compared with the classical hydrodynamic expressions. It was shown that a kinetic correction to the drift velocity stems from a contribution of the off-diagonal component of the stress tensor. This correction becomes essential if the drift velocity in the crossed electric and magnetic fields would be comparable to the thermal velocity of electrons. The electron temperature has three different components at a nonzero effective collision frequency and two different components in the limit when the collision frequency tends to zero. It is shown that, in the presence of ionization collisions, the components of the heat flux have additives that are not related to the temperature gradient, and arise because of the electron drift. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50P5103A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50P5103A">Effects of carrier concentrations on the charge transport properties in monolayer silicene</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Abidin, B. I.; Yeoh, K. H.; Ong, D. S.; Yong, T. K. 2017-10-01 Using analytical band Monte Carlo approach, we have carried out a systematic study on the effects of carrier concentrations on the steady-state and transient electron transports that occur within a monolayer silicene. In particular, we have observed the following: First at steady-state, the electron mobility reduces with higher carrier concentrations. Secondly, in the transient regime we found that the drift velocity overshoot can be controlled by varying the carrier concentrations. We uncover that at carrier concentration of 1 × 1013 cm-2, the drift velocity overshoot can reach up to 3.8 × 107 cm s-1 which is close to the steady-state drift velocity saturation of graphene. Thirdly, the distance of the velocity over shoot can be further extended with higher carrier concentrations. Our findings could be useful and can be used as benchmark for future development of nanoscale silicene based devices. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JInst..12C6014T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JInst..12C6014T">Central Drift Chamber for Belle-II</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Taniguchi, N. 2017-06-01 The Central Drift Chamber (CDC) is the main device for tracking and identification of charged particles for Belle-II experiment. The Belle-II CDC is cylindrical wire chamber with 14336 sense wires, 2.3 m-length and 2.2 m-diameter. The wire chamber and readout electronics have been completely replaced from the Belle CDC. The new readout electronics system must handle higher trigger rate of 30 kHz with less dead time at the design luminosity of 8 × 1035 cm-2s-1. The front-end electronics are located close to detector and send digitized signal through optical fibers. The Amp-Shaper-Discriminator chips, FADC and FPGA are assembled on a single board. Belle-II CDC with readout electronics has been installed successfully in Belle structure in October 2016. We will present overview of the Belle-II CDC and status of commissioning with cosmic ray. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997PhPl....4.4331S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997PhPl....4.4331S">Electron transport fluxes in potato plateau regime</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shaing, K. C.; Hazeltine, R. D. 1997-12-01 Electron transport fluxes in the potato plateau regime are calculated from the solutions of the drift kinetic equation and fluid equations. It is found that the bootstrap current density remains finite in the region close to the magnetic axis, although it decreases with increasing collision frequency. This finite amount of the bootstrap current in the relatively collisional regime is important in modeling tokamak startup with 100% bootstrap current. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87j5119Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87j5119Z">A long time low drift integrator with temperature control</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhang, Donglai; Yan, Xiaolan; Zhang, Enchao; Pan, Shimin 2016-10-01 The output of an operational amplifier always contains signals that could not have been predicted, even with knowledge of the input and an accurately determined closed-loop transfer function. These signals lead to integrator zero-drift over time. A new type of integrator system with a long-term low-drift characteristic has therefore been designed. The integrator system is composed of a temperature control module and an integrator module. The aluminum printed circuit board of the integrator is glued to a thermoelectric cooler to maintain the electronic components at a stable temperature. The integration drift is automatically compensated using an analog-to-digital converter/proportional integration/digital-to-analog converter control circuit. Performance testing in a standard magnet shows that the proposed integrator, which has an integration time constant of 10 ms, has a low integration drift (<5 mV) over 1000 s after repeated measurements. The integrator can be used for magnetic flux measurements in most tokamaks and in the wire rope nondestructive test. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27802726','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27802726">A long time low drift integrator with temperature control.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Zhang, Donglai; Yan, Xiaolan; Zhang, Enchao; Pan, Shimin 2016-10-01 The output of an operational amplifier always contains signals that could not have been predicted, even with knowledge of the input and an accurately determined closed-loop transfer function. These signals lead to integrator zero-drift over time. A new type of integrator system with a long-term low-drift characteristic has therefore been designed. The integrator system is composed of a temperature control module and an integrator module. The aluminum printed circuit board of the integrator is glued to a thermoelectric cooler to maintain the electronic components at a stable temperature. The integration drift is automatically compensated using an analog-to-digital converter/proportional integration/digital-to-analog converter control circuit. Performance testing in a standard magnet shows that the proposed integrator, which has an integration time constant of 10 ms, has a low integration drift (<5 mV) over 1000 s after repeated measurements. The integrator can be used for magnetic flux measurements in most tokamaks and in the wire rope nondestructive test. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Prama..88...23M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Prama..88...23M">Nonlinear waves in electron-positron-ion plasmas including charge separation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mugemana, A.; Moolla, S.; Lazarus, I. J. 2017-02-01 Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth and spiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E 0 was reduced. The results are compared with satellite observations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E..85A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E..85A">Ionospheric Plasma Drift Analysis Technique Based On Ray Tracing</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ari, Gizem; Toker, Cenk 2016-07-01 Ionospheric drift measurements provide important information about the variability in the ionosphere, which can be used to quantify ionospheric disturbances caused by natural phenomena such as solar, geomagnetic, gravitational and seismic activities. One of the prominent ways for drift measurement depends on instrumentation based measurements, e.g. using an ionosonde. The drift estimation of an ionosonde depends on measuring the Doppler shift on the received signal, where the main cause of Doppler shift is the change in the length of the propagation path of the signal between the transmitter and the receiver. Unfortunately, ionosondes are expensive devices and their installation and maintenance require special care. Furthermore, the ionosonde network over the world or even Europe is not dense enough to obtain a global or continental drift map. In order to overcome the difficulties related to an ionosonde, we propose a technique to perform ionospheric drift estimation based on ray tracing. First, a two dimensional TEC map is constructed by using the IONOLAB-MAP tool which spatially interpolates the VTEC estimates obtained from the EUREF CORS network. Next, a three dimensional electron density profile is generated by inputting the TEC estimates to the IRI-2015 model. Eventually, a close-to-real situation electron density profile is obtained in which ray tracing can be performed. These profiles can be constructed periodically with a period of as low as 30 seconds. By processing two consequent snapshots together and calculating the propagation paths, we estimate the drift measurements over any coordinate of concern. We test our technique by comparing the results to the drift measurements taken at the DPS ionosonde at Pruhonice, Czech Republic. This study is supported by TUBITAK 115E915 and Joint TUBITAK 114E092 and AS CR14/001 projects. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12212170D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12212170D">Energetic Electron Acceleration and Injection During Dipolarization Events in Mercury's Magnetotail</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dewey, Ryan M.; Slavin, James A.; Raines, Jim M.; Baker, Daniel N.; Lawrence, David J. 2017-12-01 Energetic particle bursts associated with dipolarization events within Mercury's magnetosphere were first observed by Mariner 10. The events appear analogous to particle injections accompanying dipolarization events at Earth. The Energetic Particle Spectrometer (3 s resolution) aboard MESSENGER determined the particle bursts are composed entirely of electrons with energies ≳ 300 keV. Here we use the Gamma-Ray Spectrometer high-time-resolution (10 ms) energetic electron measurements to examine the relationship between energetic electron injections and magnetic field dipolarization in Mercury's magnetotail. Between March 2013 and April 2015, we identify 2,976 electron burst events within Mercury's magnetotail, 538 of which are closely associated with dipolarization events. These dipolarizations are detected on the basis of their rapid ( 2 s) increase in the northward component of the tail magnetic field (ΔBz 30 nT), which typically persists for 10 s. Similar to those at Earth, we find that these dipolarizations appear to be low-entropy, depleted flux tubes convecting planetward following the collapse of the inner magnetotail. We find that electrons experience brief, yet intense, betatron and Fermi acceleration during these dipolarizations, reaching energies 130 keV and contributing to nightside precipitation. Thermal protons experience only modest betatron acceleration. While only 25% of energetic electron events in Mercury's magnetotail are directly associated with dipolarization, the remaining events are consistent with the Near-Mercury Neutral Line model of magnetotail injection and eastward drift about Mercury, finding that electrons may participate in Shabansky-like closed drifts about the planet. Magnetotail dipolarization may be the dominant source of energetic electron acceleration in Mercury's magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24357370','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24357370">Cryo-electron microscopy of membrane proteins.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Goldie, Kenneth N; Abeyrathne, Priyanka; Kebbel, Fabian; Chami, Mohamed; Ringler, Philippe; Stahlberg, Henning 2014-01-01 Electron crystallography is used to study membrane proteins in the form of planar, two-dimensional (2D) crystals, or other crystalline arrays such as tubular crystals. This method has been used to determine the atomic resolution structures of bacteriorhodopsin, tubulin, aquaporins, and several other membrane proteins. In addition, a large number of membrane protein structures were studied at a slightly lower resolution, whereby at least secondary structure motifs could be identified.In order to conserve the structural details of delicate crystalline arrays, cryo-electron microscopy (cryo-EM) allows imaging and/or electron diffraction of membrane proteins in their close-to-native state within a lipid bilayer membrane.To achieve ultimate high-resolution structural information of 2D crystals, meticulous sample preparation for electron crystallography is of outmost importance. Beam-induced specimen drift and lack of specimen flatness can severely affect the attainable resolution of images for tilted samples. Sample preparations that sandwich the 2D crystals between symmetrical carbon films reduce the beam-induced specimen drift, and the flatness of the preparations can be optimized by the choice of the grid material and the preparation protocol.Data collection in the cryo-electron microscope using either the imaging or the electron diffraction mode has to be performed applying low-dose procedures. Spot-scanning further reduces the effects of beam-induced drift. Data collection using automated acquisition schemes, along with improved and user-friendlier data processing software, is increasingly being used and is likely to bring the technique to a wider user base. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPU11002K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPU11002K">First Experiments with e-<m:mfenced close="" open="/"><m:mphantom><m:mpadded width="0pt">e-H-</m:mpadded></m:mphantom></m:mfenced> H- Plasmas: Enhanced Mode Damping and Transport</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kabantsev, A. A.; Thompson, K. A.; Driscoll, C. F. 2017-10-01 Negative Hydrogen ions are produced and confined in a room-temperature electron plasma, causing enhanced mode damping and particle transport effects. We accumulate an H- charge fraction nH-<m:mfenced close="" open="/"><m:mphantom><m:mpadded width="0pt">nH-ne 20 % </m:mpadded></m:mphantom></m:mfenced> ne 20 % in about 200 seconds, as externally excited H2 molecules undergo dissociative electron attachment in the plasma. The accumulated H- fraction causes a novel algebraic damping of diocotron mode amplitude A(t) , and the damping is coincident with an enhanced outward drift υr of the H- ions. That is, dA <m:mfenced close="" open="/"><m:mphantom><m:mpadded width="0pt"> dA dt = - α </m:mpadded></m:mphantom></m:mfenced> dt = - α , with α nH- *υr . We observe that heating the e-<m:mfenced close="" open="/"><m:mphantom><m:mpadded width="0pt">e-H-</m:mpadded></m:mphantom></m:mfenced> H- plasma terminates the enhanced damping and enhanced centrifugal separation, both of which resume when plasma re-cools by cyclotron radiation at B = 1.2T. Other interesting observations include: (1) enhanced e- cooling from collisions with H- cooled by neutrals; (2) enhanced damping of plasma waves due to e-<m:mfenced close="" open="/"><m:mphantom><m:mpadded width="0pt">e-H-</m:mpadded></m:mphantom></m:mfenced> H- collisional drag; (3) strong exponential damping of diocotron modes in a ``floppy'' nearly-pure H- plasma, created by rapid axial ejection of the electrons. Additional novel drift modes and instabilities are predicted theoretically in such a plasma. Supported by NSF/DoE Partnership Grants PHY-1414570 and DE-SC0008693. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li class="active">1</li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_2" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active">2</li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="21"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPG12123K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPG12123K">Two-fluid equilibrium transition during multi-pulsing CHI in spherical torus</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kanki, T.; Nagata, M. 2015-11-01 Two-fluid dynamo current drive has been studied to achieve a quasi-steady sustainment and good confinement of spherical torus (ST) plasmas by multi-pulsing CHI (M-CHI) in the HIST device. The density gradient, poloidal flow shear, and radial electric shear enhanced by applying the second CHI pulse is observed around the separatrix in the high field side to cause not only the ExB drift but also the ion diamagnetic drift, leading the two-fluid dynamo. The two-fluid equilibrium transition during the M-CHI in the ST is investigated by modelling the M-CHI in the two-fluid equilibrium calculations. The toroidal magnetic field becomes from a diamagnetic to a paramagnetic profile in the closed flux region due to the increase of the poloidal electron flow velocity in the central open flux column (OFC) region, while the diamagnetic profile is kept in the OFC region. The toroidal ion flow velocity is increased from negative to positive values in the closed flux region due to the increase in the drift velocity and the Hall effect. As the ion diamagnetic drift velocity is changed in the same direction as the ExB drift velocity around the separatrix in the high field side through the negative ion pressure gradient there, the poloidal ion flow velocity is increased in the OFC region, enhancing the flow shear. The radial electric field shear around the separatrix is enhanced due to the strong dependence on the magnetic force through the interaction of toroidal ion flow velocity and axial magnetic field. The density is decreased in the closed flux region according to the generalized Bernoulli law and its negative gradient around the separatrix steepens. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002345&hterms=energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Denergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002345&hterms=energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Denergy">MAVEN Observations of Energy-Time Dispersed Electron Signatures in Martian Crustal Magnetic Fields</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Harada, Y.; Mitchell, D. L.; Halekas, J. S.; McFadden, J. P.; Mazelle, C.; Connerney, J. E. P.; Espley, J.; Brain, D. A.; Larson, D. E.; Lillis, R. J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170002345'); toggleEditAbsImage('author_20170002345_show'); toggleEditAbsImage('author_20170002345_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170002345_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170002345_hide"> 2016-01-01 Energy-time dispersed electron signatures are observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission in the vicinity of strong Martian crustal magnetic fields. Analysis of pitch angle distributions indicates that these dispersed electrons are typically trapped on closed field lines formed above strong crustal magnetic sources. Most of the dispersed electron signatures are characterized by peak energies decreasing with time rather than increasing peak energies. These properties can be explained by impulsive and local injection of hot electrons into closed field lines and subsequent dispersion by magnetic drift of the trapped electrons. In addition, the dispersed flux enhancements are often bursty and sometimes exhibit clear periodicity, suggesting that the injection and trapping processes are intrinsically time dependent and dynamic. These MAVEN observations demonstrate that common physical processes can operate in both global intrinsic magnetospheres and local crustal magnetic fields. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26651177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26651177">Conversion electron spectrometry of Pu isotopes with a silicon drift detector.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Pommé, S; Paepen, J; Peräjärvi, K; Turunen, J; Pöllänen, R 2016-03-01 An electron spectrometry set-up was built at IRMM consisting of a vacuum chamber with a moveable source holder and windowless Peltier-cooled silicon drift detector (SDD). The SDD is well suited for measuring low-energy x rays and electrons emitted from thin radioactive sources with low self-absorption. The attainable energy resolution is better than 0.5keV for electrons of 30keV. It has been used to measure the conversion electron spectra of three plutonium isotopes, i.e. (238)Pu, (239)Pu, (240)Pu, as well as (241)Am (being a decay product of (241)Pu). The obtained mixed x-ray and electron spectra are compared with spectra obtained with a close-geometry set-up using another SDD in STUK and spectra measured with a Si(Li) detector at IRMM. The potential of conversion electron spectrometry for isotopic analysis of mixed plutonium samples is investigated. With respect to the (240)Pu/(239)Pu isotopic ratio, the conversion electron peaks of both isotopes are more clearly separated than their largely overlapping peaks in alpha spectra. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JAP...107b3710C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JAP...107b3710C">The drift-diffusion interpretation of the electron current within the organic semiconductor characterized by the bulk single energy trap level</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cvikl, B. 2010-01-01 The closed solution for the internal electric field and the total charge density derived in the drift-diffusion approximation for the model of a single layer organic semiconductor structure characterized by the bulk shallow single trap-charge energy level is presented. The solutions for two examples of electric field boundary conditions are tested on room temperature current density-voltage data of the electron conducting aluminum/tris(8-hydroxyquinoline aluminum/calcium structure [W. Brütting et al., Synth. Met. 122, 99 (2001)] for which jexp∝Va3.4, within the interval of bias 0.4 V≤Va≤7. In each case investigated the apparent electron mobility determined at given bias is distributed within a given, finite interval of values. The bias dependence of the logarithm of their lower limit, i.e., their minimum values, is found to be in each case, to a good approximation, proportional to the square root of the applied electric field. On account of the bias dependence as incorporated in the minimum value of the apparent electron mobility the spatial distribution of the organic bulk electric field as well as the total charge density turn out to be bias independent. The first case investigated is based on the boundary condition of zero electric field at the electron injection interface. It is shown that for minimum valued apparent mobilities, the strong but finite accumulation of electrons close to the anode is obtained, which characterize the inverted space charge limited current (SCLC) effect. The second example refers to the internal electric field allowing for self-adjustment of its boundary values. The total electron charge density is than found typically to be of U shape, which may, depending on the parameters, peak at both or at either Alq3 boundary. It is this example in which the proper SCLC effect is consequently predicted. In each of the above two cases, the calculations predict the minimum values of the electron apparent mobility, which substantially exceed the corresponding published measurements. For this reason the effect of the drift term alone is additionally investigated. On the basis of the published empirical electron mobilities and the diffusion term revoked, it is shown that the steady state electron current density within the Al/Alq3 (97 nm)/Ca single layer organic structure may well be pictured within the drift-only interpretation of the charge carriers within the Alq3 organic characterized by the single (shallow) trap energy level. In order to arrive at this result, it is necessary that the nonzero electric field, calculated to exist at the electron injecting Alq3/Ca boundary, is to be appropriately accounted for in the computation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6039366','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6039366">High power linear pulsed beam annealer. [Patent application</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Strathman, M.D.; Sadana, D.K.; True, R.B. 1980-11-26 A high power pulsed electron beam system for annealing semiconductors is comprised of an electron gun having a heated cathode, control grid and focus ring for confining the pulsed beam of electrons to a predetermined area, and a curved drift tube. The drift tube and an annular Faraday shield between the focus ring and the drift tube are maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring, thereby eliminating space charge limitations on the emission of electrons from said gun. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube. The magnetic field produced by the coil around the curved tube imparts motion to electrons in a spiral path for shallow penetration of the electrons into a target. It also produces a scalloped profile of the electron beam. A second drift tube spaced a predetermined distance from the curved tube is positioned with its axis aligned with the axis of the first drift tube. The second drift tube and the target holder are maintained at a reference voltage between the cathode voltage and the curved tube voltage to decelerate the electrons. A second coil surrounding the second drift tube, maintains the electron beam focused about the axis of the second drift tube. The magnetic field of the second coil comprises the electron beam to the area of the semiconductor on the target holder. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhPl...19l2508J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhPl...19l2508J">Fluid equations in the presence of electron cyclotron current drive</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jenkins, Thomas G.; Kruger, Scott E. 2012-12-01 Two-fluid equations, which include the physics imparted by an externally applied radiofrequency source near electron cyclotron resonance, are derived in their extended magnetohydrodynamic forms using the formalism of Hegna and Callen [Phys. Plasmas 16, 112501 (2009)]. The equations are compatible with the closed fluid/drift-kinetic model developed by Ramos [Phys. Plasmas 17, 082502 (2010); 18, 102506 (2011)] for fusion-relevant regimes with low collisionality and slow dynamics, and they facilitate the development of advanced computational models for electron cyclotron current drive-induced suppression of neoclassical tearing modes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22072635-fluid-equations-presence-electron-cyclotron-current-drive','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22072635-fluid-equations-presence-electron-cyclotron-current-drive">Fluid equations in the presence of electron cyclotron current drive</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Jenkins, Thomas G.; Kruger, Scott E. Two-fluid equations, which include the physics imparted by an externally applied radiofrequency source near electron cyclotron resonance, are derived in their extended magnetohydrodynamic forms using the formalism of Hegna and Callen [Phys. Plasmas 16, 112501 (2009)]. The equations are compatible with the closed fluid/drift-kinetic model developed by Ramos [Phys. Plasmas 17, 082502 (2010); 18, 102506 (2011)] for fusion-relevant regimes with low collisionality and slow dynamics, and they facilitate the development of advanced computational models for electron cyclotron current drive-induced suppression of neoclassical tearing modes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM51C..06T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM51C..06T">Modeling the Magnetopause Shadowing and Drift Orbit Bifurcation Loss during the June 2015 Dropout Event</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, W.; Cunningham, G. 2017-12-01 The relativistic electron flux in Earth's radiation belt are observed to drop by orders of magnitude on timescale of a few hours. Where do the electrons go during the dropout? This is one of the most important outstanding questions in radiation belt studies. Here we will study the 22 June 2015 dropout event which occurred during one of the largest geomagnetic storms in the last decade. A sudden and nearly complete loss of all the outer zone relativistic and ultra-relativistic electrons were observed after a strong interplanetary shock. The Last Closed Drift Shell (LCDS) calculated using the TS04 model reached as low as L*=3.7 during the shock and stay below L*=4 for 1 hour. The unusually low LCDS values suggest that magnetopause shadowing and the associated outward radial diffusion can contribute significantly to the observed dropout. In addition, Drift Orbit Bifurcation (DOB) has been suggested as an important loss mechanism for radiation belt electrons, especially when the solar wind dynamic pressure is high, but its relative importance has not been quantified. Here, we will model the June 2015 dropout event using a radial diffusion model that includes physical and event-specific inputs. First, we will trace electron drift shells based on TS04 model to identify the LCDS and bifurcation regions as a function of the 2nd adiabatic invariant (K) and time. To model magnetopause shadowing, electron lifetimes in our model will be set to electron drift periods at L*>LCDS. Electron lifetimes inside the bifurcation region have been estimated by Ukhorskiy et al. [JGR 2011, doi:10.1029/2011JA016623] as a function of L* and K, which will also be implemented in the model. This will be the first effort to include the DOB loss in a comprehensive radiation belt model. Furthermore, to realistically simulate outward radial diffusion, the new radial diffusion coefficients that are calculated based on the realistic TS04 model and include physical K dependence [Cunningham, JGR 2016, doi:10.1002/2015JA021981] will be achieved and included here. With these event-specific and physical model inputs, we will test how well the observed fast dropout during the June 2015 event can be reproduced by our model, and quantify the relative contribution of magnetopause shadowing, outward radial diffusion, and DOB to the fast electron depletion. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9547799','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9547799">Psychophysics of reading. XVII. Low-vision performance with four types of electronically magnified text.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Harland, S; Legge, G E; Luebker, A 1998-03-01 Most people with low vision need magnification to read. Page navigation is the process of moving a magnifier during reading. Modern electronic technology can provide many alternatives for navigating through text. This study compared reading speeds for four methods of displaying text. The four methods varied in their page-navigation demands. The closed-circuit television (CCTV) and MOUSE methods involved manual navigation. The DRIFT method (horizontally drifting text) involved no manual navigation, but did involve both smooth-pursuit and saccadic eye movements. The rapid serial visual presentation (RSVP) method involved no manual navigation, and relatively few eye movements. There were 7 normal subjects and 12 low-vision subjects (7 with central-field loss, CFL group, and 5 with central fields intact, CFI group). The subjects read 70-word passages at speeds that yielded good comprehension. Taking the CCTV reading speed as a benchmark, neither the normal nor low-vision subjects had significantly different speeds with the MOUSE method. As expected from the reduced navigational demands, normal subjects read faster with the DRIFT method (85% faster) and the RSVP method (169%). The CFI group read significantly faster with DRIFT (43%) and RSVP (38%). The CFL group showed no significant differences in reading speed for the four methods. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.3419T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.3419T">Modeling the Magnetopause Shadowing Loss during the October 2012 Dropout Event</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, Weichao; Cunningham, Gregory 2017-04-01 The relativistic electron flux in Earth's outer radiation belt are observed to drop by orders of magnitude on timescales of a few hours, which is called radiation belt dropouts. Where do the electrons go during the dropouts? This is one of the most important outstanding questions in radiation belt studies. Radiation belt electrons can be lost either by precipitation into the atmosphere or by transport across the magnetopause into interplanetary space. The latter mechanism is called magnetopause shadowing, usually combined with outward radial diffusion of electrons due to the sharp radial gradient it creates. In order to quantify the relative contribution of these two mechanisms to radiation belt dropout, we performed an event study on the October 2012 dropout event observed by Van Allen Probes. First, the precipitating MeV electrons observed by multiple NOAA POES satellites at low altitude did not show evidence of enhanced precipitation during the dropout, which suggested that precipitation was not the dominant loss mechanism for the event. Then, in order to simulate the magnetopause shadowing loss and outward radial diffusion during the dropout, we applied a radial diffusion model with electron lifetimes on the order of electron drift periods outside the last closed drift shell. In addition, realistic and event-specific inputs of radial diffusion coefficients (DLL) and last closed drift shell (LCDS) were implemented in the model. Specifically, we used the new DLL developed by Cunningham [JGR 2016] which were estimated in realistic TS04 [Tsyganenko and Sitnov, JGR 2005] storm time magnetic field model and included physical K (2nd adiabatic invariant) or pitch angle dependence. Event-specific LCDS traced in TS04 model with realistic K dependence was also implemented. Our simulation results showed that these event-specific inputs are critical to explain the electron dropout during the event. The new DLL greatly improved the model performance at low L* regions (L*<3.6) compared to empirical Kp-dependent DLL [Brautigam and Albert, JGR 2000] used in previous radial diffusion models. Combining the event-specific DLL and LCDS, our model well captured the magnetopause shadowing loss and reproduced the electron dropout at L*=4.0-4.5. In addition, we found the K-dependent LCDS is critical to reproduce the pitch angle dependence of the observed electron dropout. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPYI2006D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPYI2006D">Density-Gradient-Driven trapped-electron-modes in improved-confinement RFP plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Duff, James 2016-10-01 Short wavelength density fluctuations in improved-confinement MST plasmas exhibit multiple features characteristic of the trapped-electron-mode (TEM), strong evidence that drift wave turbulence emerges in RFP plasmas when transport associated with MHD tearing is reduced. Core transport in the RFP is normally governed by magnetic stochasticity stemming from long wavelength tearing modes that arise from current profile peaking. Using inductive control, the tearing modes are reduced and global confinement is increased to values expected for a comparable tokamak plasma. The improved confinement is associated with a large increase in the pressure gradient that can destabilize drift waves. The measured density fluctuations have frequencies >50 kHz, wavenumbers k_phi*rho_s<0.14, and propagate in the electron drift direction. Their spectral emergence coincides with a sharp decrease in fluctuations associated with global tearing modes. Their amplitude increases with the local density gradient, and they exhibit a density-gradient threshold at R/L_n 15, higher than in tokamak plasmas by R/a. the GENE code, modified for RFP equilibria, predicts the onset of microinstability for these strong-gradient plasma conditions. The density-gradient-driven TEM is the dominant instability in the region where the measured density fluctuations are largest, and the experimental threshold-gradient is close to the predicted critical gradient for linear stability. While nonlinear analysis shows a large Dimits shift associated with predicted strong zonal flows, the inclusion of residual magnetic fluctuations causes a collapse of the zonal flows and an increase in the predicted transport to a level close to the experimentally measured heat flux. Similar circumstances could occur in the edge region of tokamak plasmas when resonant magnetic perturbations are applied for the control of ELMs. Work supported by US DOE. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22410451-relativistic-electron-motion-cylindrical-waveguide-strong-guiding-magnetic-field-high-power-microwave','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22410451-relativistic-electron-motion-cylindrical-waveguide-strong-guiding-magnetic-field-high-power-microwave">Relativistic electron motion in cylindrical waveguide with strong guiding magnetic field and high power microwave</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Wu, Ping; Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024; Sun, Jun 2015-06-15 In O-type high power microwave (HPM) devices, the annular relativistic electron beam is constrained by a strong guiding magnetic field and propagates through an interaction region to generate HPM. Some papers believe that the E × B drift of electrons may lead to beam breakup. This paper simplifies the interaction region with a smooth cylindrical waveguide to research the radial motion of electrons under conditions of strong guiding magnetic field and TM{sub 01} mode HPM. The single-particle trajectory shows that the radial electron motion presents the characteristic of radial guiding-center drift carrying cyclotron motion. The radial guiding-center drift is spatiallymore » periodic and is dominated by the polarization drift, not the E × B drift. Furthermore, the self fields of the beam space charge can provide a radial force which may pull electrons outward to some extent but will not affect the radial polarization drift. Despite the radial drift, the strong guiding magnetic field limits the drift amplitude to a small value and prevents beam breakup from happening due to this cause.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870025029&hterms=quasi+particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dquasi%2Bparticle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870025029&hterms=quasi+particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dquasi%2Bparticle">A model of impulsive acceleration and transport of energetic particles in Mercury's magnetosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Baker, D. N.; Simpson, J. A.; Eraker, J. H. 1986-01-01 A qualitative model of substorm processes in the Mercury magnetosphere is presented based on Mariner 10 observations obtained in 1974-1975. The model is predicated on close analogies observed with the terrestrial case. Particular emphasis is given to energetic particle phenomena as observed by Mariner on March 29, 1974. The suggestion is supported that energetic particles up to about 500 keV are produced by strong induced electric fields at 3 to about 6 Mercury radii in the Hermean tail in association with substorm neutral line formation. The bursts of energetic particles produced are, in this model, subsequently confined on closed field lines near Mercury and drift adiabatically on quasi-trapped orbits for many tens of seconds. Such gradient and curvature drift of the particles can explain prominent periodicities of 5-10 s seen in the Mariner for greater than 170-keV electron flux profiles. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BrJPh..47..617A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BrJPh..47..617A">Linear and Nonlinear Coupling of Electrostatic Drift and Acoustic Perturbations in a Nonuniform Bi-Ion Plasma with Non-Maxwellian Electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ali, Gul-e.; Ahmad, Ali; Masood, W.; Mirza, Arshad M. 2017-12-01 Linear and nonlinear coupling of drift and ion acoustic waves are studied in a nonuniform magnetized plasma comprising of Oxygen and Hydrogen ions with nonthermal distribution of electrons. It has been observed that different ratios of ion number densities and kappa and Cairns distributed electrons significantly modify the linear dispersion characteristics of coupled drift-ion acoustic waves. In the nonlinear regime, KdV (for pure drift waves) and KP (for coupled drift-ion acoustic waves) like equations have been derived to study the nonlinear evolution of drift solitary waves in one and two dimensions. The dependence of drift solitary structures on different ratios of ion number densities and nonthermal distribution of electrons has also been explored in detail. It has been found that the ratio of the diamagnetic drift velocity to the velocity of the nonlinear structure determines the existence regimes for the drift solitary waves. The present investigation may be beneficial to understand the formation of solitons in the ionospheric F-region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999PhDT.......228S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999PhDT.......228S">Gyrofluid theory and simulation of electromagnetic turbulence and transport in tokamak plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Snyder, Philip Benjamin 1999-11-01 Turbulence and transport in toroidal plasmas is studied via the development of an electromagnetic gyrofluid model, and its implementation in realistic nonlinear simulations. This work extends earlier electrostatic gyrofluid models to include magnetic fluctuations and non-adiabatic passing electron dynamics. A new set of electron fluid equations is derived from the drift kinetic equation, via an expansion in the electron-ion mass ratio. These electron equations include descriptions of linear and nonlinear drift motion, Landau damping, and electron-ion collisions. Ion moment equations are derived from the electromagnetic gyrokinetic equation, and the gyrokinetic Poisson's Equation and Ampere's Law close the system. The model is benchmarked with linear gyrokinetic calculations, and good agreement is found for both the finite-β ion temperature gradient (ITG) and kinetic Alfvén ballooning (KBM) instabilities. Nonlinear simulations of ITG and KBM-driven turbulence are performed in toroidal flux tube geometry at a range of values of plasma β, and electromagnetic effects are found to significantly impact turbulent heat and particle transport. At low values of β, transport is reduced, as expected due to the finite-β stabilization of the ITG mode. However, as β approaches the Ideal-MHD stability threshold, transport can increase. In the presence of dissipation provided by a model of electron Landau damping and electron-ion collisions, this transport increase can be quite dramatic. Finally, the results of the simulations are compared to tokamak experiments, and encouraging agreement is found with measured density and temperature fluctuation spectra. Direct comparisons of transport fluxes reveal that electromagnetic effects are important at characteristic edge parameters, bringing predicted fluxes more closely in line with observations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020014793&hterms=by-product&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dby-product','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020014793&hterms=by-product&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dby-product">The Electron Drift Technique for Measuring Electric and Magnetic Fields</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Paschmann, G.; McIlwain, C. E.; Quinn, J. M.; Torbert, R. B.; Whipple, E. C.; Christensen, John (Technical Monitor) 1998-01-01 The electron drift technique is based on sensing the drift of a weak beam of test electrons that is caused by electric fields and/or gradients in the magnetic field. These quantities can, by use of different electron energies, in principle be determined separately. Depending on the ratio of drift speed to magnetic field strength, the drift velocity can be determined either from the two emission directions that cause the electrons to gyrate back to detectors placed some distance from the emitting guns, or from measurements of the time of flight of the electrons. As a by-product of the time-of-flight measurements, the magnetic field strength is also determined. The paper describes strengths and weaknesses of the method as well as technical constraints. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RScI...88f3706G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RScI...88f3706G">Developments on a SEM-based X-ray tomography system: Stabilization scheme and performance evaluation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gomes Perini, L. A.; Bleuet, P.; Filevich, J.; Parker, W.; Buijsse, B.; Kwakman, L. F. Tz. 2017-06-01 Recent improvements in a SEM-based X-ray tomography system are described. In this type of equipment, X-rays are generated through the interaction between a highly focused electron-beam and a geometrically confined anode target. Unwanted long-term drifts of the e-beam can lead to loss of X-ray flux or decrease of spatial resolution in images. To circumvent this issue, a closed-loop control using FFT-based image correlation is integrated to the acquisition routine, in order to provide an in-line drift correction. The X-ray detection system consists of a state-of-the-art scientific CMOS camera (indirect detection), featuring high quantum efficiency (˜60%) and low read-out noise (˜1.2 electrons). The system performance is evaluated in terms of resolution, detectability, and scanning times for applications covering three different scientific fields: microelectronics, technical textile, and material science. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/21069973-radiation-from-space-charge-dominated-linear-electron-beam','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21069973-radiation-from-space-charge-dominated-linear-electron-beam">Radiation from a space charge dominated linear electron beam</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Biswas, Debabrata 2008-01-15 It is commonly known that radiation loss in linear beam transport is largely unimportant. For a space charge dominated linear beam, however, radiation power loss can be an appreciable fraction of the injected beam power [Biswas, Kumar, and Puri, Phys. Plasmas 14, 094702 (2007)]. Exploring this further, the electromagnetic nature of radiation due to the passage of a space charge dominated electron beam in a 'closed' drift tube is explicitly demonstrated by identifying the cavity modes where none existed prior to beam injection. It is further shown that even in an 'open' drift tube from which radiation may leak, themore » modes that escape contribute to the time variation of the electric and magnetic fields in the transient phase. As the window opening increases, the oscillatory transient phase disappears altogether. However, the 'bouncing ball' modes survive and can be observed between the injection and collection plates.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27830111','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27830111">Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Baker, Daniel N; Dewey, Ryan M; Lawrence, David J; Goldsten, John O; Peplowski, Patrick N; Korth, Haje; Slavin, James A; Krimigis, Stamatios M; Anderson, Brian J; Ho, George C; McNutt, Ralph L; Raines, Jim M; Schriver, David; Solomon, Sean C 2016-03-01 The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer, as well as data arising from energetic electrons recorded by the X-Ray Spectrometer and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary nightside. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and prenoon sectors, at times executing multiple complete drifts around the planet to form "quasi-trapped" populations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6361090','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6361090">Broad-band beam buncher</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F. 1984-03-20 A broad-band beam bunther is disclosed, comprising an evacuated housing, an electron gun therein for producing an electron beam, a buncher cavity having entrance and exit openings through which the beam is directed, grids across such openings, a source providing a positive DC voltage between the cavity and the electron gun, a drift tube through which the electron beam travels in passing through such cavity, grids across the ends of such drift tube, gaps being provided between the drift tube grids and the entrance and exit grids, a modulator for supplying an ultrahigh frequency modulating signal to the drift tube for producing velocity modulation of the electrons in the beam, a drift space in the housing through which the velocity modulated electron beam travels and in which the beam is bunched, and a discharge opening from such drift tube and having a grid across such opening through which the bunched electron beam is discharged into an accelerator or the like. The buncher cavity and the drift tube may be arranged to constitute an extension of a coaxial transmission line which is employed to deliver the modulating signal from a signal source. The extended transmission line may be terminated in its characteristic impedance to afford a broad- </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active">2</li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active">3</li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996SPIE.2895..505Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SPIE.2895..505Z">Closed-loop fiber optic gyroscope with homodyne detection</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhu, Yong; Qin, BingKun; Chen, Shufen 1996-09-01 Interferometric fiber optic gyroscope (IFOG) has been analyzed with autocontrol theory in this paper. An open-loop IFOG system is not able to restrain the bias drift, but a closed-loop IFOG system can do it very well using negative feedback in order to suppress zero drift. The result of our theoretic analysis and computer simulation indicate that the bias drift of a closed-loop system is smaller than an open- loop one. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1367091-heat-flux-modeling-using-ion-drift-effects-diii-mode-plasmas-resonant-magnetic-perturbations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1367091-heat-flux-modeling-using-ion-drift-effects-diii-mode-plasmas-resonant-magnetic-perturbations">Heat flux modeling using ion drift effects in DIII-D H-mode plasmas with resonant magnetic perturbations</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Wingen, Andreas; Schmitz, Oliver; Evans, Todd E.; ... 2014-01-01 The heat flux patterns measured in low-collisionality DIII-D H-mode plasmas strongly deviate from simultaneously measured CII emission patterns, used as indicator of particle flux, during applied resonant magnetic perturbations. While the CII emission clearly shows typical striations, which are similar to magnetic footprint patterns obtained from vacuum field line tracing, the heat flux is usually dominated by one large peak at the strike point position. The vacuum approximation, which only considers applied magnetic fields and neglects plasma response and plasma effects, cannot explain the shape of the observed heat flux pattern. One possible explanation is the effect of particle drifts.more » This is included in the field line equations and the results are discussed with reference to the measurement. Electrons and ions show di fferent drift motions at thermal energy levels in a guiding center approximation. While electrons hardly deviate from the field lines, ions can drift several centimetres away from field line flux surfaces. A model is presented in which an ion heat flux, based on the ion drift motion from various kinetic energies as they contribute to a thermal Maxwellian distribution, is calculated. The simulated heat flux is directly compared to measurements with a varying edge safety factor q95. This analysis provides evidence for the dominate e ect of high-energy ions in carrying heat from the plasma inside the separatrix to the target. High-energy ions are deposited close to the unperturbed strike line while low-energy ions can travel into the striated magnetic topology.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864481','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864481">High power linear pulsed beam annealer</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Strathman, Michael D.; Sadana, Devendra K.; True, Richard B. 1983-01-01 A high power pulsed electron beam is produced in a system comprised of an electron gun having a heated cathode, control grid, focus ring, and a curved drift tube. The drift tube is maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring and to thereby eliminate space charge. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube and imparts motion on electrons in a spiral path for shallow penetration of the electrons into a target. The curvature of the tube is selected so there is no line of sight between the cathode and a target holder positioned within a second drift tube spaced coaxially from the curved tube. The second tube and the target holder are maintained at a reference voltage that decelerates the electrons. A second coil surrounding the second drift tube maintains the electron beam focused about the axis of the second drift tube and compresses the electron beam to the area of the target. The target holder can be adjusted to position the target where the cross section of the beam matches the area of the target. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1247498-electron-drift-large-scale-solid-xenon','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1247498-electron-drift-large-scale-solid-xenon">Electron drift in a large scale solid xenon</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Yoo, J.; Jaskierny, W. F. 2015-08-21 A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7 cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163 K), the drift speed is 0.193 ± 0.003 cm/μs while the drift speed in the solid phase (157 K) is 0.397 ± 0.006 cm/μs at 900 V/cm over 8.0 cm of uniform electric fields. Furthermore, it is demonstrated that a factor twomore » faster electron drift speed in solid phase xenon compared to that in liquid in a large scale solid xenon.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1413738','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1413738">Electron Attenuation Measurement using Cosmic Ray Muons at the MicroBooNE LArTPC</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Meddage, Varuna 2017-10-01 The MicroBooNE experiment at Fermilab uses liquid argon time projection chamber (LArTPC) technology to study neutrino interactions in argon. A fundamental requirement for LArTPCs is to achieve and maintain a low level of electronegative contaminants in the liquid to minimize the capture of drifting ionization electrons. The attenuation time for the drifting electrons should be long compared to the maximum drift time, so that the signals from particle tracks that generate ionization electrons with long drift paths can be detected efficiently. In this talk we present MicroBooNE measurement of electron attenuation using cosmic ray muons. The result yields a minimummore » electron 1/e lifetime of 18 ms under typical operating conditions, which is long compared to the maximum drift time of 2.3 ms.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..116.6215J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..116.6215J">A statistical study of the inner edge of the electron plasma sheet and the net convection potential as a function of geomagnetic activity</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jiang, F.; Kivelson, M. G.; Walker, R. J.; Khurana, K. K.; Angelopoulos, V.; Hsu, T. 2011-06-01 A widely accepted explanation of the location of the inner edge of the electron plasma sheet and its dependence on electron energy is based on drift motions of individual particles. The boundary is identified as the separatrix between drift trajectories linking the tail to the dayside magnetopause (open paths) and trajectories closed around the Earth. A statistical study of the inner edge of the electron plasma sheet using THEMIS Electrostatic Analyzer plasma data from November 2007 to April 2009 enabled us to examine this model. Using a dipole magnetic field and a Volland-Stern electric field with shielding, we find that a steady state drift boundary model represents the average location of the electron plasma sheet boundary and reflects its variation with the solar wind electric field in the local time region between 21:00 and 06:00, except at high activity levels. However, the model does not reproduce the observed energy dispersion of the boundaries. We have also used the location of the inner edge of the electron plasma sheet to parameterize the potential drop of the tail convection electric field as a function of solar wind electric field (Esw) and geomagnetic activity. The range of Esw examined is small because the data were acquired near solar minimum. For the range of values tested (meaningful statistics only for Esw < 2 mV/m), reasonably good agreement is found between the potential drop of the tail convection electric field inferred from the location of the inner edge and the polar cap potential drop calculated from the model of Boyle et al. (1997). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020013937&hterms=by-product&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dby-product','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020013937&hterms=by-product&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dby-product">The Electron Drift Instrument for Cluster</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Paschmann, G.; Melzner, F.; Frenzel, R.; Vaith, H.; Parigger, P.; Pagel, U.; Bauer, O. H.; Haerendel, G.; Baumjohann, W.; Scopke, N. 1997-01-01 The Electron Drift Instrument (EDI) measures the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one or more gyrations. This drift is related to the electric field and the gradient in the magnetic field, and these quantities can, by use of different electron energies, be determined separately. As a by-product, the magnetic field strength is also measured. The present paper describes the scientific objectives, the experimental method, and the technical realization of the various elements of the instrument. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS.996a2014B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS.996a2014B">On the physics of electron transfer (drift) in the substance: about the reason of “abnormal” fast transfer of electrons in the plasma of tokamak and at known Bohm’s diffusion</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Boriev, I. A. 2018-03-01 An analysis of the problem of so-called “abnormal” fast transfer of electrons in tokamak plasma, which turned out much faster than the result of accepted calculation, is given. Such transfer of hot electrons leads to unexpectedly fast destruction of the inner tokamak wall with ejection of its matter in plasma volume, what violates a condition of plasma confinement for controlled thermonuclear fusion. It is shown, taking into account real physics of electron drift in the gas (plasma) and using the conservation law for momentum of electron transfer (drift), that the drift velocity of elastically scattered electrons should be significantly greater than that of accepted calculation. The reason is that the relaxation time of the momentum of electron transfer, to which the electron drift velocity is proportional, is significantly greater (from 16 up to 4 times) than the electron free path time. Therefore, generally accepted replacement of the relaxation time, which is unknown a priori, by the electron free path time, leads to significant (16 times for thermal electrons) underestimation of electron drift velocity (mobility). This result means, that transfer of elastically (and isotropically) scattered electrons in the gas phase should be so fast, and corresponds to multiplying coefficient (16), introduced by D. Bohm to explain the observed by him “abnormal” fast diffusion of electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA342572','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA342572">Spacecraft Interactions Studies with a 1 Kw Class Closed-Drift Hall Thruster</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1998-01-31 Closed Drift Hall thruster plume with spacecraft surfaces and systems. Two basic interaction modes were investigated: (1) the influence of the plume...Spectrometer (MBMS) capable of discerning both the mass and energy of Hall thruster plume species, and the ion acoustic wave probe to measure the drift velocity of the plume plasma. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599863-existence-regimes-formation-nonlinear-dissipative-structures-inhomogeneous-magnetoplasmas-non-maxwellian-electrons','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599863-existence-regimes-formation-nonlinear-dissipative-structures-inhomogeneous-magnetoplasmas-non-maxwellian-electrons">Existence regimes for the formation of nonlinear dissipative structures in inhomogeneous magnetoplasmas with non-Maxwellian electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Masood, W.; National Centre for Physics, Shahdara Valley Road, Islamabad; Zahoor, Sara 2016-09-15 Nonlinear dissipative structures are studied in one and two dimensions in nonuniform magnetized plasmas with non-Maxwellian electrons. The dissipation is incorporated in the system through ion-neutral collisions. Employing the drift approximation, nonlinear drift waves are derived in 1D, whereas coupled drift-ion acoustic waves are derived in 2D in the weak nonlinearity limit. It is found that the ratio of the diamagnetic drift velocity to the velocity of nonlinear structure determines the nature (compressive or rarefactive) of the shock structure. The upper and lower bounds for velocity of the nonlinear shock structures are also found. It is noticed that the existencemore » regimes for the drift shock waves in one and two dimensions for Cairns distributed electrons are very distinct from those with kappa distributed electrons. Interestingly, it is found that both compressive and rarefactive shock structures could be obtained for the one dimensional drift waves with kappa distributed electrons.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23i2104M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23i2104M">Existence regimes for the formation of nonlinear dissipative structures in inhomogeneous magnetoplasmas with non-Maxwellian electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Masood, W.; Zahoor, Sara; Gul-e-Ali, Ahmad, Ali 2016-09-01 Nonlinear dissipative structures are studied in one and two dimensions in nonuniform magnetized plasmas with non-Maxwellian electrons. The dissipation is incorporated in the system through ion-neutral collisions. Employing the drift approximation, nonlinear drift waves are derived in 1D, whereas coupled drift-ion acoustic waves are derived in 2D in the weak nonlinearity limit. It is found that the ratio of the diamagnetic drift velocity to the velocity of nonlinear structure determines the nature (compressive or rarefactive) of the shock structure. The upper and lower bounds for velocity of the nonlinear shock structures are also found. It is noticed that the existence regimes for the drift shock waves in one and two dimensions for Cairns distributed electrons are very distinct from those with kappa distributed electrons. Interestingly, it is found that both compressive and rarefactive shock structures could be obtained for the one dimensional drift waves with kappa distributed electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5076489','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5076489">Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high‐resolution observations from MESSENGER</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Dewey, Ryan M.; Lawrence, David J.; Goldsten, John O.; Peplowski, Patrick N.; Korth, Haje; Slavin, James A.; Krimigis, Stamatios M.; Anderson, Brian J.; Ho, George C.; McNutt, Ralph L.; Raines, Jim M.; Schriver, David; Solomon, Sean C. 2016-01-01 Abstract The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer, as well as data arising from energetic electrons recorded by the X‐Ray Spectrometer and Gamma‐Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near‐tail region of Mercury's magnetosphere and are subsequently “injected” onto closed magnetic field lines on the planetary nightside. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and prenoon sectors, at times executing multiple complete drifts around the planet to form “quasi‐trapped” populations. PMID:27830111 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/553014-electron-transport-fluxes-potato-plateau-regime','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/553014-electron-transport-fluxes-potato-plateau-regime"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Shaing, K.C.; Hazeltine, R.D. Electron transport fluxes in the potato plateau regime are calculated from the solutions of the drift kinetic equation and fluid equations. It is found that the bootstrap current density remains finite in the region close to the magnetic axis, although it decreases with increasing collision frequency. This finite amount of the bootstrap current in the relatively collisional regime is important in modeling tokamak startup with 100{percent} bootstrap current. {copyright} {ital 1997 American Institute of Physics.} </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.3692O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.3692O">On the Role of Last Closed Drift Shell Dynamics in Driving Fast Losses and Van Allen Radiation Belt Extinction</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Olifer, L.; Mann, I. R.; Morley, S. K.; Ozeke, L. G.; Choi, D. 2018-05-01 We present observations of very fast radiation belt loss as resolved using high time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The time scale of these losses is revealed to be as short as ˜0.5-2 hr during intense magnetic storms, with some storms demonstrating almost total loss on these time scales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around 2 weeks. By contrast, the moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. We compute the last closed drift shell (LCDS) for each of these four storms and show a very strong correspondence between the LCDS and the loss patterns of trapped electrons in each storm. Most significantly, the location of the LCDS closely mirrors the high time resolution losses observed in GPS flux. The fast losses occur on a time scale shorter than the Van Allen Probes orbital period, are explained by proximity to the LCDS, and progress inward, consistent with outward transport to the LCDS by fast ultralow frequency wave radial diffusion. Expressing the location of the LCDS in L*, and not model magnetopause standoff distance in units of RE, clearly reveals magnetopause shadowing as the cause of the fast loss observed by the GPS satellites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/879771','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/879771">Electron Gun For Multiple Beam Klystron Using Magnetic Focusing</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Ives, R. Lawrence; Miram, George; Krasnykh, Anatoly 2004-07-27 An RF device comprising a plurality of drift tubes, each drift tube having a plurality of gaps defining resonant cavities, is immersed in an axial magnetic field. RF energy is introduced at an input RF port at one of these resonant cavities and collected at an output RF port at a different RF cavity. A plurality of electron beams passes through these drift tubes, and each electron beam has an individual magnetic shaping applied which enables confined beam transport through the drift tubes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/865752','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865752">Broad-band beam buncher</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Goldberg, David A.; Flood, William S.; Arthur, Allan A.; Voelker, Ferdinand 1986-01-01 A broad-band beam buncher is disclosed, comprising an evacuated housing, an electron gun therein for producing an electron beam, a buncher cavity having entrance and exit openings through which the beam is directed, grids across such openings, a source providing a positive DC voltage between the cavity and the electron gun, a drift tube through which the electron beam travels in passing through such cavity, grids across the ends of such drift tube, gaps being provided between the drift tube grids and the entrance and exit grids, a modulator for supplying an ultrahigh frequency modulating signal to the drift tube for producing velocity modulation of the electrons in the beam, a drift space in the housing through which the velocity modulated electron beam travels and in which the beam is bunched, and a discharge opening from such drift tube and having a grid across such opening through which the bunched electron beam is discharged into an accelerator or the like. The buncher cavity and the drift tube may be arranged to constitute an extension of a coaxial transmission line which is employed to deliver the modulating signal from a signal source. The extended transmission line may be terminated in its characteristic impedance to afford a broad-band response and the device as a whole designed to effect broad-band beam coupling, so as to minimize variations of the output across the response band. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24646996','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24646996">Rotationally driven 'zebra stripes' in Earth's inner radiation belt.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Ukhorskiy, A Y; Sitnov, M I; Mitchell, D G; Takahashi, K; Lanzerotti, L J; Mauk, B H 2014-03-20 Structured features on top of nominally smooth distributions of radiation-belt particles at Earth have been previously associated with particle acceleration and transport mechanisms powered exclusively by enhanced solar-wind activity. Although planetary rotation is considered to be important for particle acceleration at Jupiter and Saturn, the electric field produced in the inner magnetosphere by Earth's rotation can change the velocity of trapped particles by only about 1-2 kilometres per second, so rotation has been thought inconsequential for radiation-belt electrons with velocities of about 100,000 kilometres per second. Here we report that the distributions of energetic electrons across the entire spatial extent of Earth's inner radiation belt are organized in regular, highly structured and unexpected 'zebra stripes', even when the solar-wind activity is low. Modelling reveals that the patterns are produced by Earth's rotation. Radiation-belt electrons are trapped in Earth's dipole-like magnetic field, where they undergo slow longitudinal drift motion around the planet because of the gradient and curvature of the magnetic field. Earth's rotation induces global diurnal variations of magnetic and electric fields that resonantly interact with electrons whose drift period is close to 24 hours, modifying electron fluxes over a broad energy range into regular patterns composed of multiple stripes extending over the entire span of the inner radiation belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21307544','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21307544">Silicon drift detectors with on-chip electronics for x-ray spectroscopy.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Fiorini, C; Longoni, A; Hartmann, R; Lechner, P; Strüder, L 1997-01-01 The silicon drift detector (SDD) is a semiconductor device based on high resistivity silicon fully depleted through junctions implanted on both sides of the semiconductor wafer. The electrons generated by the ionizing radiation are driven by means of a suitable electric field from the point of interaction toward a collecting anode of small capacitance, independent of the active area of the detector. A suitably designed front-end JFET has been directly integrated on the detector chip close to the anode region, in order to obtain a nearly ideal capacitive matching between detector and transistor and to minimize the stray capacitances of the connections. This feature allows it to reach high energy resolution also at high count rates and near room temperature. The present work describes the structure and the performance of SDDs specially designed for high resolution spectroscopy with soft x rays at high detection rate. Experimental results of SDDs used in spectroscopy applications are also reported. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SSRv..199..283T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SSRv..199..283T">The Electron Drift Instrument for MMS</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Torbert, R. B.; Vaith, H.; Granoff, M.; Widholm, M.; Gaidos, J. A.; Briggs, B. H.; Dors, I. G.; Chutter, M. W.; Macri, J.; Argall, M.; Bodet, D.; Needell, J.; Steller, M. B.; Baumjohann, W.; Nakamura, R.; Plaschke, F.; Ottacher, H.; Hasiba, J.; Hofmann, K.; Kletzing, C. A.; Bounds, S. R.; Dvorsky, R. T.; Sigsbee, K.; Kooi, V. 2016-03-01 The Electron Drift Instrument (EDI) on the Magnetospheric Multiscale (MMS) mission measures the in-situ electric and magnetic fields using the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one or more gyrations. This drift is related to the electric field and, to a lesser extent, the gradient in the magnetic field. Although these two quantities can be determined separately by use of different electron energies, for MMS regions of interest the magnetic field gradient contribution is negligible. As a by-product of the drift determination, the magnetic field strength and constraints on its direction are also determined. The present paper describes the scientific objectives, the experimental method, and the technical realization of the various elements of the instrument on MMS. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1013621','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1013621">Linear electronic field time-of-flight ion mass spectrometers</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Funsten, Herbert O. 2010-08-24 Time-of-flight mass spectrometer comprising a first drift region and a second drift region enclosed within an evacuation chamber; a means of introducing an analyte of interest into the first drift region; a pulsed ionization source which produces molecular ions from said analyte of interest; a first foil positioned between the first drift region and the second drift region, which dissociates said molecular ions into constituent atomic ions and emits secondary electrons; an electrode which produces secondary electrons upon contact with a constituent atomic ion in second drift region; a stop detector comprising a first ion detection region and a second ion detection region; and a timing means connected to the pulsed ionization source, to the first ion detection region, and to the second ion detection region. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active">3</li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active">4</li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21960629','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21960629">MESSENGER observations of transient bursts of energetic electrons in Mercury's magnetosphere.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Ho, George C; Krimigis, Stamatios M; Gold, Robert E; Baker, Daniel N; Slavin, James A; Anderson, Brian J; Korth, Haje; Starr, Richard D; Lawrence, David J; McNutt, Ralph L; Solomon, Sean C 2011-09-30 The MESSENGER spacecraft began detecting energetic electrons with energies greater than 30 kilo-electron volts (keV) shortly after its insertion into orbit about Mercury. In contrast, no energetic protons were observed. The energetic electrons arrive as bursts lasting from seconds to hours and are most intense close to the planet, distributed in latitude from the equator to the north pole, and present at most local times. Energies can exceed 200 keV but often exhibit cutoffs near 100 keV. Angular distributions of the electrons about the magnetic field suggest that they do not execute complete drift paths around the planet. This set of characteristics demonstrates that Mercury's weak magnetic field does not support Van Allen-type radiation belts, unlike all other planets in the solar system with internal magnetic fields. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPJ11118D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPJ11118D">Density-Gradient-Driven trapped-electron-modes in improved-confinement RFP plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Duff, James; Sarff, John; Ding, Weixing; Brower, David; Parke, Eli; Chapman, Brett; Terry, Paul; Pueschel, M. J.; Williams, Zach 2017-10-01 Short wavelength density fluctuations in improved-confinement MST plasmas exhibit multiple features characteristic of the trapped-electron-mode (TEM). Core transport in the RFP is normally governed by magnetic stochasticity stemming from long wavelength tearing modes that arise from current profile peaking, which are suppressed via inductive control for this work. The improved confinement is associated with an increase in the pressure gradient that can destabilize drift waves. The measured density fluctuations have f 50 kHz, kϕρs < 0.14 , and propagate in the electron drift direction. Their spectral emergence coincides with a sharp decrease in global tearing mode associated fluctuations, their amplitude increases with local density gradient, and they exhibit a density-gradient threshold at R /Ln 15 . The GENE code, modified for the RFP, predicts the onset of density-gradient-driven TEM for these strong-gradient plasma conditions. While nonlinear analysis shows a large Dimits shift associated with predicted strong zonal flows, the inclusion of residual magnetic fluctuations, comparable to experimental magnetic fluctuations, causes a collapse of the zonal flows and an increase in the predicted transport to a level close to the experimentally measured heat flux. Work supported by US DOE. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999SPIE.3768..240C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999SPIE.3768..240C">Novel x-ray silicon detector for 2D imaging and high-resolution spectroscopy</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Castoldi, Andrea; Gatti, Emilio; Guazzoni, Chiara; Longoni, Antonio; Rehak, Pavel; Strueder, Lothar 1999-10-01 A novel x-ray silicon detector for 2D imaging has been recently proposed. The detector, called Controlled-Drift Detector, is operated in integrate-readout mode. Its basic feature is the fast transport of the integrated charge to the output electrode by means of a uniform drift field. The drift time of the charge packet identifies the pixel of incidence. A new architecture to implement the Controlled- Drift Detector concept will be presented. The potential wells for the integration of the signal charge are obtained by means of a suitable pattern of deep n-implants and deep p-implants. During the readout mode the signal electrons are transferred in the drift channel that flanks each column of potential wells where they drift towards the collecting electrode at constant velocity. The first experimental measurements demonstrate the successful integration, transfer and drift of the signal electrons. The low output capacitance of the readout electrode together with the on- chip front-end electronics allows high resolution spectroscopy of the detected photons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RScI...85g3505W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RScI...85g3505W">Breakdown assisted by a novel electron drift injection in the J-TEXT tokamak</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wang, Nengchao; Jin, Hai; Zhuang, Ge; Ding, Yonghua; Pan, Yuan; Cen, Yishun; Chen, Zhipeng; Huang, Hai; Liu, Dequan; Rao, Bo; Zhang, Ming; Zou, Bichen 2014-07-01 A novel electron drift injection (EDI) system aiming to improve breakdown behavior has been designed and constructed on the Joint Texas EXperiment Tokamak Tokamak. Electrons emitted by the system undergo the E×B drift, ∇B drift and curvature drift in sequence in order to traverse the confining magnetic field. A local electrostatic well, generated by a concave-shaped plate biased more negative than the cathode, is introduced to interrupt the emitted electrons moving along the magnetic field line (in the parallel direction) in an attempt to bring an enhancement of the injection efficiency and depth. A series of experiments have demonstrated the feasibility of this method, and a penetration distance deeper than 9.5 cm is achieved. Notable breakdown improvements, including the reduction of breakdown delay and average loop voltage, are observed for discharges assisted by EDI. The lower limit of successfully ionized pressure is expanded. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1438365-role-last-closed-drift-shell-dynamics-driving-fast-losses-van-allen-radiation-belt-extinction','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1438365-role-last-closed-drift-shell-dynamics-driving-fast-losses-van-allen-radiation-belt-extinction">On the role of last closed drift shell dynamics in driving fast losses and Van Allen radiation belt extinction</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Olifer, Leonid; Mann, Ian R.; Morley, Steven Karl; ... 2018-04-20 We present observations of very fast radiation belt loss as resolved using high time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The time scale of these losses is revealed to be as short as ~0.5–2 hr during intense magnetic storms, with some storms demonstrating almost total loss on these time scales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around 2 weeks. By contrast, themore » moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. Here, we compute the last closed drift shell (LCDS) for each of these four storms and show a very strong correspondence between the LCDS and the loss patterns of trapped electrons in each storm. Most significantly, the location of the LCDS closely mirrors the high time resolution losses observed in GPS flux. The fast losses occur on a time scale shorter than the Van Allen Probes orbital period, are explained by proximity to the LCDS, and progress inward, consistent with outward transport to the LCDS by fast ultralow frequency wave radial diffusion. Expressing the location of the LCDS in L*, and not model magnetopause standoff distance in units of RE, clearly reveals magnetopause shadowing as the cause of the fast loss observed by the GPS satellites.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/1438365-role-last-closed-drift-shell-dynamics-driving-fast-losses-van-allen-radiation-belt-extinction','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1438365-role-last-closed-drift-shell-dynamics-driving-fast-losses-van-allen-radiation-belt-extinction">On the role of last closed drift shell dynamics in driving fast losses and Van Allen radiation belt extinction</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Olifer, Leonid; Mann, Ian R.; Morley, Steven Karl We present observations of very fast radiation belt loss as resolved using high time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The time scale of these losses is revealed to be as short as ~0.5–2 hr during intense magnetic storms, with some storms demonstrating almost total loss on these time scales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around 2 weeks. By contrast, themore » moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. Here, we compute the last closed drift shell (LCDS) for each of these four storms and show a very strong correspondence between the LCDS and the loss patterns of trapped electrons in each storm. Most significantly, the location of the LCDS closely mirrors the high time resolution losses observed in GPS flux. The fast losses occur on a time scale shorter than the Van Allen Probes orbital period, are explained by proximity to the LCDS, and progress inward, consistent with outward transport to the LCDS by fast ultralow frequency wave radial diffusion. Expressing the location of the LCDS in L*, and not model magnetopause standoff distance in units of RE, clearly reveals magnetopause shadowing as the cause of the fast loss observed by the GPS satellites.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018TePhL..44..260P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018TePhL..44..260P">Increasing Saturated Electron-Drift Velocity in Donor-Acceptor Doped pHEMT Heterostructures</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Protasov, D. Yu.; Gulyaev, D. V.; Bakarov, A. K.; Toropov, A. I.; Erofeev, E. V.; Zhuravlev, K. S. 2018-03-01 Field dependences of the electron-drift velocity in typical pseudomorphic high-electron-mobility transistor (pHEMT) heteroepitaxial structures (HESs) and in those with donor-acceptor doped (DApHEMT) heterostructures with quantum-well (QW) depth increased by 0.8-0.9 eV with the aid of acceptor layers have been studied by a pulsed technique. It is established that the saturated electron-drift velocity in DA-pHEMT-HESs is 1.2-1.3 times greater than that in the usual pHEMT-HESs. The electroluminescence (EL) spectra of DA-pHEMT-HESs do not contain emission bands related to the recombination in widebandgap layers (QW barriers). The EL intensity in these HESs is not saturated with increasing electric field. This is indicative of a suppressed real-space transfer of hot electrons from QW to barrier layers, which accounts for the observed increase in the saturated electron-drift velocity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22490108-analytic-formula-relativistic-incoherent-thomson-backscattering-spectrum-drifting-bi-maxwellian-plasma','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22490108-analytic-formula-relativistic-incoherent-thomson-backscattering-spectrum-drifting-bi-maxwellian-plasma">An analytic formula for the relativistic incoherent Thomson backscattering spectrum for a drifting bi-Maxwellian plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Naito, O. 2015-08-15 An analytic formula has been derived for the relativistic incoherent Thomson backscattering spectrum for a drifting anisotropic plasma when the scattering vector is parallel to the drifting direction. The shape of the scattering spectrum is insensitive to the electron temperature perpendicular to the scattering vector, but its amplitude may be modulated. As a result, while the measured temperature correctly represents the electron distribution parallel to the scattering vector, the electron density may be underestimated when the perpendicular temperature is higher than the parallel temperature. Since the scattering spectrum in shorter wavelengths is greatly enhanced by the existence of drift, themore » diagnostics might be used to measure local electron current density in fusion plasmas.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM21A2423P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM21A2423P">Characterization of Field Line Topologies Near the Magnetopause Using Electron Pitch Angle Measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Payne, D.; Argall, M. R.; Dors, I.; Ergun, R.; Farrugia, C. J.; Giles, B. L.; Russell, C.; Torbert, R. B.; Vaith, H.; Magnes, W. 2016-12-01 The electron drift instrument (EDI) on the Magnetospheric Multiscale (MMS) mission detects 0 and 180 degree pitch angle electrons on millisecond timescales. Using this data, we observe rapid variation of these electron fluxes in regions close to the magnetopause boundary. These variations in flux provide key insights into the dynamic field line configurations that arise from reconnection. These variations in the field detected by the spacecraft may be indicative of rapid reconnection or oscillations in the position of the boundary itself. By investigating these fluctuations near the magnetopause, we may be able to discover which of these processes, if any, are occurring. The results of this investigation may provide further insight into the process of reconnection and its effect on magnetic field topologies in the magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PlST...20b5401Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PlST...20b5401Z">Simulation of propagation of the HPM in the low-pressure argon plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhigang, LI; Zhongcai, YUAN; Jiachun, WANG; Jiaming, SHI 2018-02-01 The propagation of the high-power microwave (HPM) with a frequency of 6 GHz in the low-pressure argon plasma was studied by the method of fluid approximation. The two-dimensional transmission model was built based on the wave equation, the electron drift-diffusion equations and the heavy species transport equations, which were solved by means of COMSOL Multiphysics software. The simulation results showed that the propagation characteristic of the HPM was closely related to the average electron density of the plasma. The attenuation of the transmitted wave increased nonlinearly with the electron density. Specifically, the growth of the attenuation slowed down as the electron density increased uniformly. In addition, the concrete transmission process of the HPM wave in the low-pressure argon plasma was given. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5936L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5936L">Characteristics of DC electric fields at dipolarization fronts</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Laakso, Harri; Escoubet, Philippe; Masson, Arnaud 2016-04-01 We investigate the characteristics of DC electric field at dipolarization fronts and BBF's using multi-point Cluster observations. There are plenty of important issues that are considered, such as what kind of DC electric fields exist in such events and what are their spatial scales. One can also recognize if electrons and ions perform ExB drift motions in these events. To investigate this, we take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer. The calibrated observations of the three spectrometers are used to determine the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. This investigation also helps understand how well different measurements are calibrated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA133462','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA133462">An Investigation of Accelerating Mechanisms in a Plasma Focus Relevant to Interrupting Switches.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1983-07-01 drift region so as to reduce beam loss due to contact with the conductive walls of the drift tube . The beam guiding apparatus was shown *i to increase...secondary discharge had an adverse effect on the trans- mission of the electron beam through the drift tube . This effect, which was shown to be...the electron beam from entering the drift tube region. .A -4 Io For CiA&- TAR - ’ ’--, U Unclassified SECURITY CLASSIFICATION OF THIS PAGEfhe, 00i Ent </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM24B..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM24B..03C">Effects of Drift-Shell Splitting by Chorus Waves on Radiation Belt Electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chan, A. A.; Zheng, L.; O'Brien, T. P., III; Tu, W.; Cunningham, G.; Elkington, S. R.; Albert, J. 2015-12-01 Drift shell splitting in the radiation belts breaks all three adiabatic invariants of charged particle motion via pitch angle scattering, and produces new diffusion terms that fully populate the diffusion tensor in the Fokker-Planck equation. Based on the stochastic differential equation method, the Radbelt Electron Model (REM) simulation code allows us to solve such a fully three-dimensional Fokker-Planck equation, and to elucidate the sources and transport mechanisms behind the phase space density variations. REM has been used to perform simulations with an empirical initial phase space density followed by a seed electron injection, with a Tsyganenko 1989 magnetic field model, and with chorus wave and ULF wave diffusion models. Our simulation results show that adding drift shell splitting changes the phase space location of the source to smaller L shells, which typically reduces local electron energization (compared to neglecting drift-shell splitting effects). Simulation results with and without drift-shell splitting effects are compared with Van Allen Probe measurements. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/21347116-generation-zonal-flows-electrostatic-drift-waves-electron-positron-ion-plasmas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21347116-generation-zonal-flows-electrostatic-drift-waves-electron-positron-ion-plasmas">Generation of zonal flows by electrostatic drift waves in electron-positron-ion plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kaladze, T. D.; I. Vekua Institute of Applied Mathematics, Tbilisi State University, 2 University Str., 0186 Tbilisi; Shad, M. 2010-02-15 Generation of large-scale zonal flows by comparatively small-scale electrostatic drift waves in electron-positron-ion plasmas is considered. The generation mechanism is based on the parametric excitation of convective cells by finite amplitude drift waves having arbitrary wavelengths (as compared with the ion Larmor radius of plasma ions at the plasma electron temperature). Temperature inhomogeneity of electrons and positrons is taken into account assuming ions to be cold. To describe the generation of zonal flow generalized Hasegawa-Mima equation containing both vector and two scalar (of different nature) nonlinearities is used. A set of coupled equations describing the nonlinear interaction of drift wavesmore » and zonal flows is deduced. Explicit expressions for the maximum growth rate as well as for the optimal spatial dimensions of the zonal flows are obtained. Enriched possibilities of zonal flow generation with different growth rates are revealed. The present theory can be used for interpretations of drift wave observations in laboratory and astrophysical plasmas.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/298289-novel-drift-structures-silicon-compound-semiconductor-ray-gamma-ray-detectors','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/298289-novel-drift-structures-silicon-compound-semiconductor-ray-gamma-ray-detectors">Novel drift structures for silicon and compound semiconductor X-ray and gamma-ray detectors</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Patt, B.E.; Iwanczyk, J.S. Recently developed silicon- and compound-semiconductor-based drift detector structures have produced excellent performance for charged particles, X-rays, and gamma rays and for low-signal visible light detection. The silicon drift detector (SDD) structures that the authors discuss relate to direct X-ray detectors and scintillation photon detectors coupled with scintillators for gamma rays. Recent designs include several novel features that ensure very low dark current and hence low noise. In addition, application of thin window technology ensures a very high quantum efficiency entrance window on the drift photodetector. The main features of the silicon drift structures for X rays and light detection aremore » very small anode capacitance independent of the overall detector size, low noise, and high throughput. To take advantage of the small detector capacitance, the first stage of the electronics needs to be integrated into the detector anode. In the gamma-ray application, factors other than electronic noise dominate, and there is no need to integrate the electronics into the anode. Thus, a different drift structure is needed in conjunction with a high-Z material. The main features in this case are large active detector volume and electron-only induced signal.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1256396-inward-drift-runaway-electrons-during-plateau-phase-runaway-current','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1256396-inward-drift-runaway-electrons-during-plateau-phase-runaway-current">On the inward drift of runaway electrons during the plateau phase of runaway current</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Hu, Di; Qin, Hong 2016-03-29 The well observed inward drift of current carrying runaway electrons during runaway plateau phase after disruption is studied by considering the phase space dynamic of runaways in a large aspect ratio toroidal system. We consider the case where the toroidal field is unperturbed and the toroidal symmetry of the system is preserved. The balance between the change in canonical angular momentum and the input of mechanical angular momentum in such a system requires runaways to drift horizontally in configuration space for any given change in momentum space. The dynamic of this drift can be obtained by integrating the modified Euler-Lagrangemore » equation over one bounce time. It is then found that runaway electrons will always drift inward as long as they are decelerating. This drift motion is essentially non-linear, since the current is carried by runaways themselves, and any runaway drift relative to the magnetic axis will cause further displacement of the axis itself. A simplified analytical model is constructed to describe such inward drift both in the ideal wall case and no wall case, and the runaway current center displacement as a function of parallel momentum variation is obtained. The time scale of such displacement is estimated by considering effective radiation drag, which shows reasonable agreement with the observed displacement time scale. Furthermore, this indicates that the phase space dynamic studied here plays a major role in the horizontal displacement of runaway electrons during plateau phase. (C) 2016 AIP Publishing LLC.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599049-inward-drift-runaway-electrons-during-plateau-phase-runaway-current','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599049-inward-drift-runaway-electrons-during-plateau-phase-runaway-current">On the inward drift of runaway electrons during the plateau phase of runaway current</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hu, Di, E-mail: hudi-2@pku.edu.cn; Qin, Hong; School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei 230026 The well observed inward drift of current carrying runaway electrons during runaway plateau phase after disruption is studied by considering the phase space dynamic of runaways in a large aspect ratio toroidal system. We consider the case where the toroidal field is unperturbed and the toroidal symmetry of the system is preserved. The balance between the change in canonical angular momentum and the input of mechanical angular momentum in such a system requires runaways to drift horizontally in configuration space for any given change in momentum space. The dynamic of this drift can be obtained by integrating the modified Euler-Lagrangemore » equation over one bounce time. It is then found that runaway electrons will always drift inward as long as they are decelerating. This drift motion is essentially non-linear, since the current is carried by runaways themselves, and any runaway drift relative to the magnetic axis will cause further displacement of the axis itself. A simplified analytical model is constructed to describe such inward drift both in the ideal wall case and no wall case, and the runaway current center displacement as a function of parallel momentum variation is obtained. The time scale of such displacement is estimated by considering effective radiation drag, which shows reasonable agreement with the observed displacement time scale. This indicates that the phase space dynamic studied here plays a major role in the horizontal displacement of runaway electrons during plateau phase.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1256396','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1256396">On the inward drift of runaway electrons during the plateau phase of runaway current</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hu, Di; Qin, Hong The well observed inward drift of current carrying runaway electrons during runaway plateau phase after disruption is studied by considering the phase space dynamic of runaways in a large aspect ratio toroidal system. We consider the case where the toroidal field is unperturbed and the toroidal symmetry of the system is preserved. The balance between the change in canonical angular momentum and the input of mechanical angular momentum in such a system requires runaways to drift horizontally in configuration space for any given change in momentum space. The dynamic of this drift can be obtained by integrating the modified Euler-Lagrangemore » equation over one bounce time. It is then found that runaway electrons will always drift inward as long as they are decelerating. This drift motion is essentially non-linear, since the current is carried by runaways themselves, and any runaway drift relative to the magnetic axis will cause further displacement of the axis itself. A simplified analytical model is constructed to describe such inward drift both in the ideal wall case and no wall case, and the runaway current center displacement as a function of parallel momentum variation is obtained. The time scale of such displacement is estimated by considering effective radiation drag, which shows reasonable agreement with the observed displacement time scale. Furthermore, this indicates that the phase space dynamic studied here plays a major role in the horizontal displacement of runaway electrons during plateau phase. (C) 2016 AIP Publishing LLC.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008BASIP..25...34B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008BASIP..25...34B">Discovery of remarkable subpulse drifting pattern in PSR B0818-41</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bhattacharyya, B.; Gupta, Y.; Gil, J.; Sendyk, M. The study of pulsars showing systematic subpulse drift patterns provides important clues for understanding of pulsar emission mechanism. Pulsars with wide profiles provide extra insights because of the presence of multiple drift bands (e.g PSR B0826-34). We report the discovery of a remarkable subpulse drift pattern in a relatively less studied wide profile pulsar, PSR B0818-41, using the GMRT. We find simultaneous occurrence of three drift regions with two drift rates, an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, the two closely spaced drift regions always maintain a constant phase relationship. These unique drift properties seen for this pulsar is very rare. We interpret that the observed drift pattern is created by intersection of our line of sight (LOS) with two conal rings in a inner LOS (negative beta) geometry. We argue that the carousel rotation periodicity (P_4) and the number of sparks (N_sp) are the same for the rings and claim that P_4 is close to the measured P_3. Based on our analysis results and interpretations, we simulate the radiation from B0818-41. The simulations support our interpretations and reproduce the average profile and the observed drift pattern. The results of our study show that PSR B0818-41 is a powerful system to explore the pulsar radio emission mechanism, the implications of which are also discussed in our work. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33B2781Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33B2781Y">Radio Spectral Imaging of Reflective MHD Waves during the Impulsive Phase of a Solar Flare</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yu, S.; Chen, B.; Reeves, K. 2017-12-01 We report a new type of coherent radio bursts observed by the Karl G. Jansky Very Large Array (VLA) in 1-2 GHz during the impulsive phase of a two-ribbon flare on 2014 November 1, which we interpret as MHD waves reflected near the footpoint of flaring loops. In the dynamic spectrum, this burst starts with a positive frequency drift toward higher frequencies until it slows down near its highest-frequency boundary. Then it turns over and drifts toward lower frequencies. The frequency drift rate in its descending and ascending branch is between 50-150 MHz/s, which is much slower than type III radio bursts associated with fast electron beams but close to the well-known intermediate drift bursts, or fiber bursts, which are usually attributed to propagating whistler or Alfvenic waves. Thanks to VLA's unique capability of imaging with spectrometer-like temporal and spectral resolution (50 ms and 2 MHz), we are able to obtain an image of the radio source at every time and frequency in the dynamic spectrum where the burst is present and trace its spatial evolution. From the imaging results, we find that the radio source firstly moves downward toward one of the flaring ribbons before it "bounces off" at the lowest height (corresponding to the turnover frequency in the dynamic spectrum) and moves upward again. The measured speed in projection is at the order of 1-2 Mm/s, which is characteristic of Alfvenic or fast-mode MHD waves in the low corona. We conclude that the radio burst is emitted by trapped nonthermal electrons in the flaring loop carried along by a large-scale MHD wave. The waves are probably launched during the eruption of a magnetic flux rope in the flare impulsive phase. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active">4</li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active">5</li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864941','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864941">Method for closing a drift between adjacent in situ oil shale retorts</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Hines, Alex E. 1984-01-01 A row of horizontally spaced-apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. Each row of retorts is formed by excavating development drifts at different elevations through opposite side boundaries of a plurality of retorts in the row of retorts. Each retort is formed by explosively expanding formation toward one or more voids within the boundaries of the retort site to form a fragmented permeable mass of formation particles containing oil shale in each retort. Following formation of each retort, the retort development drifts on the advancing side of the retort are closed off by covering formation particles within the development drift with a layer of crushed oil shale particles having a particle size smaller than the average particle size of oil shale particles in the adjacent retort. In one embodiment, the crushed oil shale particles are pneumatically loaded into the development drift to pack the particles tightly all the way to the top of the drift and throughout the entire cross section of the drift. The closure between adjacent retorts provided by the finely divided oil shale provides sufficient resistance to gas flow through the development drift to effectively inhibit gas flow through the drift during subsequent retorting operations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ESASP.477..391G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ESASP.477..391G">The radiation belts and ring current: the relationship between Dst and relativistic electron phase space density</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Grande, M.; Carter, M.; Perry, C. H. 2002-03-01 We briefly review the radiation belts, before moving on to a more detailed examination of the relationship between the Disturbance Storm Time Index (Dst) and relativistic electron flux. We show that there is a strong correlation between the growth phase of storms, as represented by Dst, and dropouts in electron flux. Recovery is accompanied by growth of the electron flux. We calculate Electron Phase Space Density (PSD) as a function of adiabatic invariants using electron particle mesurements from the Imaging Electron Sensor (IES) and the High Sensitivity Telescope (HIST) on the CEPPAD experiment onboard POLAR. We present the time history of the phase space density through the year 1998 as L-sorted plots and look in detail at the May 98 storm. Comparison with the Tsyganenko 96 magnetic field model prediction for the last closed field line suggests that the loss of electrons may be directly caused by the opening of drift shells. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988PhDT........65L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988PhDT........65L">Drift Wave Simulation in Toroidal Geometry.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lebrun, Maurice Joseph, III 1988-12-01 The drift wave, a general category of plasma behavior arising from a plasma inhomogeneity, is studied using the particle simulation method. In slab geometry, the drift wave (or universal mode) is stabilized by any finite amount of magnetic shear. In toroidal geometry, however, the coupling of the poloidal harmonics gives rise to a new branch of drift wave eigenmodes called the toroidicity -induced mode, which is predicted to be unstable in some regimes. The drift wave in a toroidal system is intrinsically three-dimensional, and is sensitive to the handling of the parallel electron dynamics, the (nearly) perpendicular wave dynamics, and the radial variation of magnetic field vector (shear). A simulation study must therefore be kinetic in nature, motivating the extension of particle simulation techniques to complex geometries. From this effort a three dimensional particle code in a toroidal coordinate system has been developed and applied to the toroidal drift wave problem. The code uses an (r,theta,phi) -type coordinate system, and a nonuniform radial grid that increases resolution near the mode-rational surfaces. Full ion dynamics and electron guiding center dynamics are employed. Further, the algorithm incorporates a straightforward limiting process to cylindrical geometry and slab geometry, enabling comparison to the theoretical results in these regimes. Simulations of the density-driven modes in toroidal geometry retain a single toroidal mode number (n = 9). In this regime, the poloidal harmonics are expected to be strongly coupled, giving rise to the marginally unstable toroidicity-induced drift mode. Analysis of the simulation data reveals a strong, low-frequency response that peaks near each mode rational surface. Further, the characteristic oscillation frequencies persist from one mode rational surface to the next, which identifies them as multiple harmonics of the toroidicity-induced mode. The lowest harmonic occurs at a frequency of omega/ omega^{*} ~ 0.26, which is reasonably close to the prediction of linear theory. Interferogram analysis of these modes indicates a "ballooning" structure toward the outside of the torus. The amplitude of the potential is observed to grow exponentially for the m = 8 through m = 10 poloidal mode numbers, with a growth rate of approximately gamma/omega ^{*} ~ 0.075. Saturation occurs at time t ~ 1000 Omega_sp{i}{-1}, and may be caused by quasilinear flattening of the density profile. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22486461-pulsed-electron-beam-propagation-argon-nitrogen-gas-mixture','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22486461-pulsed-electron-beam-propagation-argon-nitrogen-gas-mixture"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V. The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N{sub 2}). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24f4504H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24f4504H">Effects of E × B drift on electron transport across the magnetic field in a miniature microwave discharge neutralizer</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hiramoto, Kenta; Nakagawa, Yuichi; Koizumi, Hiroyuki; Takao, Yoshinori 2017-06-01 Using a three-dimensional particle-in-cell model, electron transport across a magnetic field has been investigated by obtaining the time-varying electric field and plasma parameters in a miniature microwave discharge neutralizer. The size of the neutralizer is 20 × 20 × 4 mm3. Ring-shaped antenna producing 4.2 GHz microwaves and permanent magnets for xenon plasma discharges are present inside. There are four orifices for electron extraction. The simulation area consists of both the discharge chamber and the vacuum region for the extraction. The numerical results show that radial striped patterns occur where the peak electron density is obtained, and the patterns seem to rotate in the azimuthal direction. This characteristic structure is very similar to recent results obtained in Hall thrusters and is probably due to the electron drift instability. Owing to the plasma structure, the azimuthal electric field is generated, which results in the E × B drift velocity in the axial direction with the radial magnetic field of the permanent magnets. This E × B drift velocity is a key factor in the electron transport across the magnetic field, leading to the electron extraction from the discharge chamber. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/875061','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/875061">Gamma-ray detector employing scintillators coupled to semiconductor drift photodetectors</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Iwanczyk, Jan S.; Patt, Bradley E. Radiation detectors according to one embodiment of the invention are implemented using scintillators combined with a semiconductor drift photodetectors wherein the components are specifically constructed in terms of their geometry, dimensions, and arrangement so that the scintillator decay time and drift time in the photodetector pairs are matched in order to achieve a greater signal-to-noise ratio. The detectors may include electronics for amplification of electrical signals produced by the silicon drift photodetector, the amplification having a shaping time optimized with respect to the decay time of the scintillator and time spread of the signal in the silicon drift photodetector tomore » substantially maximize the ratio of the signal to the electronic noise.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM22A..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM22A..07L">Multi-point Measurements of Relativistic Electrons in the Magnetosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Li, X.; Selesnick, R.; Baker, D. N.; Blake, J. B.; Schiller, Q.; Blum, L. W.; Zhao, H.; Jaynes, A. N.; Kanekal, S. 2014-12-01 We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26366744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26366744">Correction of image drift and distortion in a scanning electron microscopy.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Jin, P; Li, X 2015-12-01 Continuous research on small-scale mechanical structures and systems has attracted strong demand for ultrafine deformation and strain measurements. Conventional optical microscope cannot meet such requirements owing to its lower spatial resolution. Therefore, high-resolution scanning electron microscope has become the preferred system for high spatial resolution imaging and measurements. However, scanning electron microscope usually is contaminated by distortion and drift aberrations which cause serious errors to precise imaging and measurements of tiny structures. This paper develops a new method to correct drift and distortion aberrations of scanning electron microscope images, and evaluates the effect of correction by comparing corrected images with scanning electron microscope image of a standard sample. The drift correction is based on the interpolation scheme, where a series of images are captured at one location of the sample and perform image correlation between the first image and the consequent images to interpolate the drift-time relationship of scanning electron microscope images. The distortion correction employs the axial symmetry model of charged particle imaging theory to two images sharing with the same location of one object under different imaging fields of view. The difference apart from rigid displacement between the mentioned two images will give distortion parameters. Three-order precision is considered in the model and experiment shows that one pixel maximum correction is obtained for the employed high-resolution electron microscopic system. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EPJWC.17402007A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EPJWC.17402007A">Development of Gating Foils To Inhibit Ion Feedback Using FPC Production Techniques</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Arai, D.; Ikematsu, K.; Sugiyama, A.; Iwamura, M.; Koto, A.; Katsuki, K.; Fujii, K.; Matsuda, T. 2018-02-01 Positive ion feedback from a gas amplification device to the drift region of the Time Projection Chamber for the ILC can deteriorate the position resolution. In order to inhibit the feedback ions, MPGD-based gating foils having good electron transmission have been developed to be used instead of the conventional wire gate. The gating foil needs to control the electric field locally in opening or closing the gate. The gating foil with a GEM (gas electron multiplier)-like structure has larger holes and smaller thickness than standard GEMs for gas amplification. It is known that the foil transmits over 80 % of electrons and blocks ions almost completely. We have developed the gating foils using flexible printed circuit (FPC) production techniques including an improved single-mask process. In this paper, we report on the production technique of 335 μm pitch, 12.5 μm thick gating foil with 80 % transmittance of electrons in ILC conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA085475','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA085475">Collective Acceleration with Rotating Relativistic Electron Beams.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1980-04-11 experiments[ where rela- tivistic electron beams were injected into neutral gas filled drift tubes . This paper presents results of recent experiments in...was applied in the drift tube . Rander7 has measured the beamfront velocity, ion yield and ion momentum distribution for non- rotating beams in hydrogen...fields (axial and azimuthal) and currents induced in the drift tube wall.8 Diode voltage and current are V - 900 kV, I - 80 kA for r" - 100 ns, with </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM22A..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM22A..07L">Characteristics of DC electric fields in transient plasma sheet events</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Laakso, H. E.; Escoubet, C. P.; Masson, A. 2015-12-01 We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29361685','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29361685">Glass Polarization Induced Drift of a Closed-Loop Micro-Accelerometer.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Zhou, Wu; He, Jiangbo; Yu, Huijun; Peng, Bei; He, Xiaoping 2018-01-20 The glass polarization effects were introduced in this paper to study the main cause of turn-on drift phenomenon of closed-loop micro-accelerometers. The glass substrate underneath the sensitive silicon structure underwent a polarizing process when the DC bias voltage was applied. The slow polarizing process induced an additional electrostatic field to continually drag the movable mass block from one position to another so that the sensing capacitance was changed, which led to an output drift of micro-accelerometers. This drift was indirectly tested by experiments and could be sharply reduced by a shielding layer deposited on the glass substrate because the extra electrical filed was prohibited from generating extra electrostatic forces on the movable fingers of the mass block. The experimental results indicate the average magnitude of drift decreased about 73%, from 3.69 to 0.99 mV. The conclusions proposed in this paper showed a meaningful guideline to improve the stability of micro-devices based on silicon-on-glass structures. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5793661','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5793661">Glass Polarization Induced Drift of a Closed-Loop Micro-Accelerometer</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> He, Jiangbo; Yu, Huijun; Peng, Bei; He, Xiaoping 2018-01-01 The glass polarization effects were introduced in this paper to study the main cause of turn-on drift phenomenon of closed-loop micro-accelerometers. The glass substrate underneath the sensitive silicon structure underwent a polarizing process when the DC bias voltage was applied. The slow polarizing process induced an additional electrostatic field to continually drag the movable mass block from one position to another so that the sensing capacitance was changed, which led to an output drift of micro-accelerometers. This drift was indirectly tested by experiments and could be sharply reduced by a shielding layer deposited on the glass substrate because the extra electrical filed was prohibited from generating extra electrostatic forces on the movable fingers of the mass block. The experimental results indicate the average magnitude of drift decreased about 73%, from 3.69 to 0.99 mV. The conclusions proposed in this paper showed a meaningful guideline to improve the stability of micro-devices based on silicon-on-glass structures. PMID:29361685 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900064041&hterms=movement+Brownian&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmovement%2BBrownian','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900064041&hterms=movement+Brownian&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmovement%2BBrownian">Transition density of one-dimensional diffusion with discontinuous drift</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Zhang, Weijian 1990-01-01 The transition density of a one-dimensional diffusion process with a discontinuous drift coefficient is studied. A probabilistic representation of the transition density is given, illustrating the close connections between discontinuities of the drift and Brownian local times. In addition, some explicit results are obtained based on the trivariate density of Brownian motion, its occupation, and local times. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667239-quasi-periodic-acceleration-electrons-flare-july','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667239-quasi-periodic-acceleration-electrons-flare-july">QUASI-PERIODIC ACCELERATION OF ELECTRONS IN THE FLARE ON 2012 JULY 19</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Huang, Jing; Kontar, Eduard P.; Nakariakov, Valery M. Quasi-periodic pulsations (QPPs) of nonthermal emission in an M7.7 class flare on 2012 July 19 are investigated with spatially resolved observations at microwave and HXR bands and with spectral observations at decimetric, metric waves. Microwave emission at 17 GHz of two footpoints, HXR emission at 20–50 keV of the north footpoint and loop top, and type III bursts at 0.7–3 GHz show prominent in-phase oscillations at 270 s. The microwave emission of the loop leg has less pulsation but stronger emission. Through the estimation of plasma density around the loop top from EUV observations, we find that the local plasmamore » frequency would be 1.5 GHz or even higher. Thus, type III bursts at 700 MHz originate above the loop top. Quasi-periodic acceleration or injection of energetic electrons is proposed to dominate these in-phase QPPs of nonthermal emission from footpoints, loop top, and above. In the overlying region, drifting pulsations (DPS) at 200–600 MHz oscillate at a distinct period (200 s). Its global structure drifts toward lower frequency, which is closely related to upward plasmoids observed simultaneously from EUV emission. Hence, nonthermal emission from overlying plasmoids and underlying flaring loops show different oscillating periods. Two individual systems of quasi-periodic acceleration of electrons are proposed to coincide in the bi-direction outflows from the reconnection region.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DPPCP9107I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DPPCP9107I">Measurements of dynamo effect on double-CHI pulse ST plasmas on HIST</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ito, K.; Hanao, T.; Ishihara, M.; Matsumoto, K.; Higashi, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M. 2011-10-01 Coaxial Helicity injection (CHI) is an efficient current-drive method used in spheromak and spherical torus (ST) experiments. An anticipated issue for CHI is achieving good energy confinement, since it relies on the magnetic relaxation and dynamo. This is essentially because CHI cannot drive a dynamo directly inside a closed magnetic flux surface. Thus, it is an important issue to investigate dynamo effect to explore CHI current drive mechanisms in a new approach such as Multi-pulsing CHI method. To study the dynamo model with two-fluid Hall effects, we have started from the generalized Ohm law. We have measured each MHD dynamo term and Hall dynamo term separately by using Mach probe and Hall probe involving 3-axis magnetic pick-up coils. The result shows that the induced electric field due to MHD dynamo is large enough to sustain the mean toroidal current against resistive decay in the core region. In the other hand, the anti-dynamo effect in the MHD dynamo term is observed in the central open flux column (OFC) region. From the viewpoint of two-fluid theory, ion diamagnetic drift is opposite to the electron diamagnetic drift, maybe resulting in the anti-dynamo effect. Hall dynamo may arise from the fluctuating electron diamagnetic current due to high electron density gradient which is large in the OFC region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NIMPA.853...44T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NIMPA.853...44T">A gating grid driver for time projection chambers</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tangwancharoen, S.; Lynch, W. G.; Barney, J.; Estee, J.; Shane, R.; Tsang, M. B.; Zhang, Y.; Isobe, T.; Kurata-Nishimura, M.; Murakami, T.; Xiao, Z. G.; Zhang, Y. F.; SπRIT Collaboration 2017-05-01 A simple but novel driver system has been developed to operate the wire gating grid of a Time Projection Chamber (TPC). This system connects the wires of the gating grid to its driver via low impedance transmission lines. When the gating grid is open, all wires have the same voltage allowing drift electrons, produced by the ionization of the detector gas molecules, to pass through to the anode wires. When the grid is closed, the wires have alternating higher and lower voltages causing the drift electrons to terminate at the more positive wires. Rapid opening of the gating grid with low pickup noise is achieved by quickly shorting the positive and negative wires to attain the average bias potential with N-type and P-type MOSFET switches. The circuit analysis and simulation software SPICE shows that the driver restores the gating grid voltage to 90% of the opening voltage in less than 0.20 μs, for small values of the termination resistors. When tested in the experimental environment of a time projection chamber larger termination resistors were chosen so that the driver opens the gating grid in 0.35 μs. In each case, opening time is basically characterized by the RC constant given by the resistance of the switches and terminating resistors and the capacitance of the gating grid and its transmission line. By adding a second pair of N-type and P-type MOSFET switches, the gating grid is closed by restoring 99% of the original charges to the wires within 3 μs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM43B2722C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM43B2722C">Coupling of Outward Radial Diffusion and Losses at the Magnetopause in the Outer Radiation Belt</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Castillo Tibocha, A. M.; Shprits, Y.; Drozdov, A.; Kellerman, A. C.; Aseev, N. 2017-12-01 Sudden dropouts observed in relativistic electron fluxes within the radiation belts are one the most studied and yet poorly understood features of the dynamics of radiation belts. A number of physical processes contributing to these dropout events are triggered by solar wind drivers. Magnetopause losses are one of the most effective mechanisms involved here and usually occur when drifting particles reach the boundary or when inward motion of the magnetopause crosses closed particle drift shells. In both cases, particles are rapidly transported into interplanetary space generating sharp gradients in electron PSD that will promote further outward radial diffusion of particles due to adiabatic transport and the influence of outward ULF waves. Studies suggest that the coupling of these two mechanisms explains nearly all the depletion of MeV electrons observed in the outer region of the radiation belts (L*>5). In this study, we present a simple approach to model electron losses at the magnetopause and outward radial diffusion in the outer radiation belt during geomagnetic storm time. Measured upstream solar wind parameters were used to calculate the radial distance of the subsolar point as proposed by Shue et al. (1997), which was defined as the radial extent of our assumed dipole field configuration. Radial diffusion was modelled using the empirical Kp-dependent DLL [Brautigam and Albert, JGR 2000] diffusion coefficient, which is included in the 3D Versatile Electron Radiation Belt (VERB) code. Simulations of geomagnetic storms were performed in order to evaluate the effects of the integrated mechanisms and the results were compared with Van Allen probe satellite data. Our simulation results reproduce well the observed loss at the magnetopause and electron depletion in the outer radiation belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24568718','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24568718">Averaging scheme for atomic resolution off-axis electron holograms.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Niermann, T; Lehmann, M 2014-08-01 All micrographs are limited by shot-noise, which is intrinsic to the detection process of electrons. For beam insensitive specimen this limitation can in principle easily be circumvented by prolonged exposure times. However, in the high-resolution regime several instrumental instabilities limit the applicable exposure time. Particularly in the case of off-axis holography the holograms are highly sensitive to the position and voltage of the electron-optical biprism. We present a novel reconstruction algorithm to average series of off-axis holograms while compensating for specimen drift, biprism drift, drift of biprism voltage, and drift of defocus, which all might cause problematic changes from exposure to exposure. We show an application of the algorithm utilizing also the possibilities of double biprism holography, which results in a high quality exit-wave reconstruction with 75 pm resolution at a very high signal-to-noise ratio. Copyright © 2014 Elsevier Ltd. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1336433','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1336433">Scalability, Scintillation Readout and Charge Drift in a Kilogram Scale Solid Xenon Particle Detector</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Yoo, J.; Cease, H.; Jaskierny, W. F. 2014-10-23 We report a demonstration of the scalability of optically transparent xenon in the solid phase for use as a particle detector above a kilogram scale. We employ a liquid nitrogen cooled cryostat combined with a xenon purification and chiller system to measure the scintillation light output and electron drift speed from both the solid and liquid phases of xenon. Scintillation light output from sealed radioactive sources is measured by a set of high quantum efficiency photomultiplier tubes suitable for cryogenic applications. We observed a reduced amount of photons in solid phase compared to that in liquid phase. We used amore » conventional time projection chamber system to measure the electron drift time in a kilogram of solid xenon and observed faster electron drift speed in the solid phase xenon compared to that in the liquid phase.« less </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active">5</li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active">6</li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EPJC...70..755A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EPJC...70..755A">Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic Calorimeter using Cosmic Muons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adorisio, C.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahmed, H.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Aktas, A.; Alam, M. S.; Alam, M. A.; Albert, J.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Andeen, T.; Anders, C. F.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Antonaki, A.; Antonelli, M.; Antonelli, S.; Antos, J.; Antunovic, B.; Anulli, F.; Aoun, S.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Argyropoulos, T.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Arutinov, D.; Asai, M.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asner, D.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avolio, G.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bacci, C.; Bach, A.; Bachacou, H.; Bachas, K.; Backes, M.; Badescu, E.; Bagnaia, P.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Baltasar Dos Santos Pedrosa, F.; Banas, E.; Banerjee, P.; Banerjee, S.; Banfi, D.; Bangert, A.; Bansal, V.; Baranov, S. P.; Baranov, S.; Barashkou, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baron, S.; Baroncelli, A.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Barros, N.; Bartoldus, R.; Bartsch, D.; Bastos, J.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Bauer, F.; Bawa, H. S.; Bazalova, M.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Becerici, N.; Bechtle, P.; Beck, G. A.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Bedajanek, I.; Beddall, A. J.; Beddall, A.; Bednár, P.; Bednyakov, V. A.; Bee, C.; Begel, M.; Behar Harpaz, S.; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Belotskiy, K.; Beltramello, O.; Ami, S. Ben; Benary, O.; Benchekroun, D.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benincasa, G. P.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Besana, M. I.; Besson, N.; Bethke, S.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bocci, A.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A.; Bondarenko, V. G.; Bondioli, M.; Boonekamp, M.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Bosteels, M.; Boterenbrood, H.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brubaker, E.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.; Buchanan, J.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Budick, B.; Büscher, V.; Bugge, L.; Bulekov, O.; Bunse, M.; Buran, T.; Burckhart, H.; Burdin, S.; Burgess, T.; Burke, S.; Busato, E.; Bussey, P.; Buszello, C. P.; Butin, F.; Butler, B.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Byatt, T.; Caballero, J.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Caloi, R.; Calvet, D.; Camarri, P.; Cambiaghi, M.; Cameron, D.; Campabadal Segura, F.; Campana, S.; Campanelli, M.; Canale, V.; Canelli, F.; Canepa, A.; Cantero, J.; Capasso, L.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Caracinha, D.; Caramarcu, C.; Cardarelli, R.; Carli, T.; Carlino, G.; Carminati, L.; Caron, B.; Caron, S.; Carrillo Montoya, G. D.; Carron Montero, S.; Carter, A. A.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Cascella, M.; Caso, C.; Castaneda Hernadez, A. M.; Castaneda-Miranda, E.; Castillo Gimenez, V.; Castro, N.; Cataldi, G.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Cattani, G.; Caughron, S.; Cauz, D.; Cavalleri, P.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cetin, S. 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S.; Levonian, S.; Lewandowska, M.; Leyton, M.; Li, H.; Li, J.; Li, S.; Li, X.; Liang, Z.; Liang, Z.; Liberti, B.; Lichard, P.; Lichtnecker, M.; Lie, K.; Liebig, W.; Liko, D.; Lilley, J. N.; Lim, H.; Limosani, A.; Limper, M.; Lin, S. C.; Lindsay, S. W.; Linhart, V.; Linnemann, J. T.; Liolios, A.; Lipeles, E.; Lipinsky, L.; Lipniacka, A.; Liss, T. M.; Lissauer, D.; Lister, A.; Litke, A. M.; Liu, C.; Liu, D.; Liu, H.; Liu, J. B.; Liu, M.; Liu, S.; Liu, T.; Liu, Y.; Livan, M.; Lleres, A.; Lloyd, S. L.; Lobodzinska, E.; Loch, P.; Lockman, W. S.; Lockwitz, S.; Loddenkoetter, T.; Loebinger, F. K.; Loginov, A.; Loh, C. W.; Lohse, T.; Lohwasser, K.; Lokajicek, M.; Loken, J.; Lopes, L.; Lopez Mateos, D.; Losada, M.; Loscutoff, P.; Losty, M. J.; Lou, X.; Lounis, A.; Loureiro, K. F.; Lovas, L.; Love, J.; Love, P.; Lowe, A. J.; Lu, F.; Lu, J.; Lubatti, H. 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M.; Manousakis-Katsikakis, A.; Mansoulie, B.; Mapelli, A.; Mapelli, L.; March, L.; Marchand, J. F.; Marchese, F.; Marchiori, G.; Marcisovsky, M.; Marino, C. P.; Marques, C. N.; Marroquim, F.; Marshall, R.; Marshall, Z.; Martens, F. K.; Marti I Garcia, S.; Martin, A. J.; Martin, A. J.; Martin, B.; Martin, B.; Martin, F. F.; Martin, J. P.; Martin, T. A.; Martin Dit Latour, B.; Martinez, M.; Martinez Outschoorn, V.; Martini, A.; Martyniuk, A. C.; Maruyama, T.; Marzano, F.; Marzin, A.; Masetti, L.; Mashimo, T.; Mashinistov, R.; Masik, J.; Maslennikov, A. L.; Massaro, G.; Massol, N.; Mastroberardino, A.; Masubuchi, T.; Mathes, M.; Matricon, P.; Matsunaga, H.; Matsushita, T.; Mattravers, C.; Maxfield, S. J.; May, E. N.; Mayne, A.; Mazini, R.; Mazur, M.; Mazzanti, M.; Mazzanti, P.; Mc Donald, J.; Mc Kee, S. P.; McCarn, A.; McCarthy, R. L.; McCubbin, N. A.; McFarlane, K. W.; McGlone, H.; McHedlidze, G.; McLaren, R. A.; McMahon, S. J.; McMahon, T. R.; McPherson, R. A.; Meade, A.; Mechnich, J.; Mechtel, M.; Medinnis, M.; Meera-Lebbai, R.; Meguro, T. M.; Mehdiyev, R.; Mehlhase, S.; Mehta, A.; Meier, K.; Meirose, B.; Melachrinos, C.; Melamed-Katz, A.; Mellado Garcia, B. R.; Meng, Z.; Menke, S.; Meoni, E.; Merkl, D.; Mermod, P.; Merola, L.; Meroni, C.; Merritt, F. S.; Messina, A. M.; Messmer, I.; Metcalfe, J.; Mete, A. S.; Meyer, J.-P.; Meyer, J.; Meyer, J.; Meyer, T. C.; Meyer, W. T.; Miao, J.; Michal, S.; Micu, L.; Middleton, R. P.; Migas, S.; Mijović, L.; Mikenberg, G.; Mikuž, M.; Miller, D. W.; Mills, W. J.; Mills, C. M.; Milov, A.; Milstead, D. A.; Minaenko, A. A.; Miñano, M.; Minashvili, I. A.; Mincer, A. I.; Mindur, B.; Mineev, M.; Ming, Y.; Mir, L. M.; Mirabelli, G.; Misawa, S.; Miscetti, S.; Misiejuk, A.; Mitrevski, J.; Mitsou, V. A.; Miyagawa, P. S.; Mjörnmark, J. U.; Mladenov, D.; Moa, T.; Moed, S.; Moeller, V.; Mönig, K.; Möser, N.; Mohn, B.; Mohr, W.; Mohrdieck-Möck, S.; Moles-Valls, R.; Molina-Perez, J.; Moloney, G.; Monk, J.; Monnier, E.; Montesano, S.; Monticelli, F.; Moore, R. W.; Mora Herrera, C.; Moraes, A.; Morais, A.; Morel, J.; Morello, G.; Moreno, D.; Llácer, M. Moreno; Morettini, P.; Morii, M.; Morley, A. K.; Mornacchi, G.; Morozov, S. V.; Morris, J. D.; Moser, H. G.; Mosidze, M.; Moss, J.; Mount, R.; Mountricha, E.; Mouraviev, S. V.; Moyse, E. J. W.; Mudrinic, M.; Mueller, F.; Mueller, J.; Mueller, K.; Müller, T. A.; Muenstermann, D.; Muir, A.; Munwes, Y.; Murillo Garcia, R.; Murray, W. J.; Mussche, I.; Musto, E.; Myagkov, A. G.; Myska, M.; Nadal, J.; Nagai, K.; Nagano, K.; Nagasaka, Y.; Nairz, A. M.; Nakamura, K.; Nakano, I.; Nakatsuka, H.; Nanava, G.; Napier, A.; Nash, M.; Nation, N. R.; Nattermann, T.; Naumann, T.; Navarro, G.; Nderitu, S. K.; Neal, H. A.; Nebot, E.; Nechaeva, P.; Negri, A.; Negri, G.; Nelson, A.; Nelson, T. K.; Nemecek, S.; Nemethy, P.; Nepomuceno, A. A.; Nessi, M.; Neubauer, M. S.; Neusiedl, A.; Neves, R. N.; Nevski, P.; Newcomer, F. M.; Nickerson, R. B.; Nicolaidou, R.; Nicolas, L.; Nicoletti, G.; Niedercorn, F.; Nielsen, J.; Nikiforov, A.; Nikolaev, K.; Nikolic-Audit, I.; Nikolopoulos, K.; Nilsen, H.; Nilsson, P.; Nisati, A.; Nishiyama, T.; Nisius, R.; Nodulman, L.; Nomachi, M.; Nomidis, I.; Nordberg, M.; Nordkvist, B.; Notz, D.; Novakova, J.; Nozaki, M.; Nožička, M.; Nugent, I. M.; Nuncio-Quiroz, A.-E.; Nunes Hanninger, G.; Nunnemann, T.; Nurse, E.; O'Neil, D. C.; O'Shea, V.; Oakham, F. G.; Oberlack, H.; Ochi, A.; Oda, S.; Odaka, S.; Odier, J.; Odino, G. A.; Ogren, H.; Oh, A.; Oh, S. H.; Ohm, C. C.; Ohshima, T.; Ohshita, H.; Ohsugi, T.; Okada, S.; Okawa, H.; Okumura, Y.; Olcese, M.; Olchevski, A. G.; Oliveira, M.; Oliveira Damazio, D.; Oliver, J.; Oliver Garcia, E.; Olivito, D.; Olszewski, A.; Olszowska, J.; Omachi, C.; Onofre, A.; Onyisi, P. U. E.; Oram, C. J.; Ordonez, G.; Oreglia, M. J.; Oren, Y.; Orestano, D.; Orlov, I.; Oropeza Barrera, C.; Orr, R. S.; Ortega, E. O.; Osculati, B.; Ospanov, R.; Osuna, C.; Otec, R.; P Ottersbach, J.; Ould-Saada, F.; Ouraou, A.; Ouyang, Q.; Owen, M.; Owen, S.; Oyarzun, A.; Ozcan, V. E.; Ozone, K.; Ozturk, N.; Pacheco Pages, A.; Padhi, S.; Padilla Aranda, C.; Paganis, E.; Pahl, C.; Paige, F.; Pajchel, K.; Palestini, S.; Pallin, D.; Palma, A.; Palmer, J. D.; Pan, Y. B.; Panagiotopoulou, E.; Panes, B.; Panikashvili, N.; Panitkin, S.; Pantea, D.; Panuskova, M.; Paolone, V.; Papadopoulou, Th. D.; Park, S. J.; Park, W.; Parker, M. A.; Parker, S. I.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pasqualucci, E.; Passardi, G.; Passeri, A.; Pastore, F.; Pastore, Fr.; Pásztor, G.; Pataraia, S.; Pater, J. R.; Patricelli, S.; Patwa, A.; Pauly, T.; Peak, L. S.; Pecsy, M.; Pedraza Morales, M. I.; Peleganchuk, S. V.; Peng, H.; Penson, A.; Penwell, J.; Perantoni, M.; Perez, K.; Perez Codina, E.; Pérez García-Estañ, M. T.; Perez Reale, V.; Perini, L.; Pernegger, H.; Perrino, R.; Perrodo, P.; Persembe, S.; Perus, P.; Peshekhonov, V. D.; Petersen, B. A.; Petersen, J.; Petersen, T. C.; Petit, E.; Petridou, C.; Petrolo, E.; Petrucci, F.; Petschull, D.; Petteni, M.; Pezoa, R.; Pfeifer, B.; Phan, A.; Phillips, A. W.; Piacquadio, G.; Piccinini, M.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pina, J.; Pinamonti, M.; Pinfold, J. L.; Ping, J.; Pinto, B.; Pizio, C.; Placakyte, R.; Plamondon, M.; Plano, W. G.; Pleier, M.-A.; Poblaguev, A.; Poddar, S.; Podlyski, F.; Poffenberger, P.; Poggioli, L.; Pohl, M.; Polci, F.; Polesello, G.; Policicchio, A.; Polini, A.; Poll, J.; Polychronakos, V.; Pomarede, D. M.; Pomeroy, D.; Pommès, K.; Pontecorvo, L.; Pope, B. G.; Popovic, D. S.; Poppleton, A.; Popule, J.; Portell Bueso, X.; Porter, R.; Pospelov, G. E.; Pospichal, P.; Pospisil, S.; Potekhin, M.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Potter, K. P.; Poulard, G.; Poveda, J.; Prabhu, R.; Pralavorio, P.; Prasad, S.; Pravahan, R.; Preda, T.; Pretzl, K.; Pribyl, L.; Price, D.; Price, L. E.; Prichard, P. M.; Prieur, D.; Primavera, M.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Prudent, X.; Przysiezniak, H.; Psoroulas, S.; Ptacek, E.; Puigdengoles, C.; Purdham, J.; Purohit, M.; Puzo, P.; Pylypchenko, Y.; Qi, M.; Qian, J.; Qian, W.; Qian, Z.; Qin, Z.; Qing, D.; Quadt, A.; Quarrie, D. R.; Quayle, W. B.; Quinonez, F.; Raas, M.; Radeka, V.; Radescu, V.; Radics, B.; Rador, T.; Ragusa, F.; Rahal, G.; Rahimi, A. M.; Rahm, D.; Rajagopalan, S.; Rammes, M.; Ratoff, P. N.; Rauscher, F.; Rauter, E.; Raymond, M.; Read, A. L.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reeves, K.; Reinherz-Aronis, E.; Reinsch, A.; Reisinger, I.; Reljic, D.; Rembser, C.; Ren, Z. L.; Renkel, P.; Rescia, S.; Rescigno, M.; Resconi, S.; Resende, B.; Reznicek, P.; Rezvani, R.; Richards, A.; Richards, R. A.; Richter, R.; Richter-Was, E.; Ridel, M.; Rieke, S.; Rijpstra, M.; Rijssenbeek, M.; Rimoldi, A.; Rinaldi, L.; Rios, R. R.; Riu, I.; Rivoltella, G.; Rizatdinova, F.; Rizvi, E. R.; Roa Romero, D. A.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J.; Robinson, M.; Robson, A.; Rocha de Lima, J. G.; Roda, C.; Roda Dos Santos, D.; Rodriguez, D.; Rodriguez Garcia, Y.; Roe, S.; Røhne, O.; Rojo, V.; Rolli, S.; Romaniouk, A.; Romanov, V. M.; Romeo, G.; Romero Maltrana, D.; Roos, L.; Ros, E.; Rosati, S.; Rosenbaum, G. A.; Rosenberg, E. I.; Rosselet, L.; Rossetti, V.; Rossi, L. P.; Rotaru, M.; Rothberg, J.; Rottländer, I.; Rousseau, D.; Royon, C. R.; Rozanov, A.; Rozen, Y.; Ruan, X.; Ruckert, B.; Ruckstuhl, N.; Rud, V. I.; Rudolph, G.; Rühr, F.; Ruggieri, F.; Ruiz-Martinez, A.; Rumyantsev, L.; Rusakovich, N. A.; Rutherfoord, J. P.; Ruwiedel, C.; Ruzicka, P.; Ryabov, Y. F.; Ryadovikov, V.; Ryan, P.; Rybkin, G.; Rzaeva, S.; Saavedra, A. F.; Sadrozinski, H. F.-W.; Sadykov, R.; Sakamoto, H.; Salamanna, G.; Salamon, A.; Saleem, M.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvachua Ferrando, B. M.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sampsonidis, D.; Samset, B. H.; Sanchis Lozano, M. A.; Sandaker, H.; Sander, H. G.; Sanders, M. P.; Sandhoff, M.; Sandstroem, R.; Sandvoss, S.; Sankey, D. P. C.; Sanny, B.; Sansoni, A.; Santamarina Rios, C.; Santi, L.; Santoni, C.; Santonico, R.; Santos, J.; Saraiva, J. G.; Sarangi, T.; Sarkisyan-Grinbaum, E.; Sarri, F.; Sasaki, O.; Sasaki, T.; Sasao, N.; Satsounkevitch, I.; Sauvage, G.; Savard, P.; Savine, A. Y.; Savinov, V.; Sawyer, L.; Saxon, D. H.; Says, L. P.; Sbarra, C.; Sbrizzi, A.; Scannicchio, D. A.; Schaarschmidt, J.; Schacht, P.; Schäfer, U.; Schaetzel, S.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Schamov, A. G.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Scherzer, M. I.; Schiavi, C.; Schieck, J.; Schioppa, M.; Schlenker, S.; Schlereth, J. L.; Schmid, P.; Schmieden, K.; Schmitt, C.; Schmitz, M.; Schott, M.; Schouten, D.; Schovancova, J.; Schram, M.; Schreiner, A.; Schroeder, C.; Schroer, N.; Schroers, M.; Schuler, G.; Schultes, J.; Schultz-Coulon, H.-C.; Schumacher, J. W.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwanenberger, C.; Schwartzman, A.; Schwemling, Ph.; Schwienhorst, R.; Schwierz, R.; Schwindling, J.; Scott, W. G.; Searcy, J.; Sedykh, E.; Segura, E.; Seidel, S. C.; Seiden, A.; Seifert, F.; Seixas, J. M.; Sekhniaidze, G.; Seliverstov, D. M.; Sellden, B.; Seman, M.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Seuster, R.; Severini, H.; Sevior, M. E.; Sfyrla, A.; Shabalina, E.; Shamim, M.; Shan, L. Y.; Shank, J. T.; Shao, Q. T.; Shapiro, M.; Shatalov, P. B.; Shaver, L.; Shaw, K.; Sherman, D.; Sherwood, P.; Shibata, A.; Shimojima, M.; Shin, T.; Shmeleva, A.; Shochet, M. J.; Shupe, M. A.; Sicho, P.; Sidoti, A.; Siebel, A.; Siegert, F.; Siegrist, J.; Sijacki, Dj.; Silbert, O.; Silva, J.; Silver, Y.; Silverstein, D.; Silverstein, S. B.; Simak, V.; Simic, Lj.; Simion, S.; Simmons, B.; Simonyan, M.; Sinervo, P.; Sinev, N. B.; Sipica, V.; Siragusa, G.; Sisakyan, A. N.; Sivoklokov, S. Yu.; Sjoelin, J.; Sjursen, T. B.; Skubic, P.; Skvorodnev, N.; Slater, M.; Slavicek, T.; Sliwa, K.; Sloper, J.; Sluka, T.; Smakhtin, V.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, B. C.; Smith, D.; Smith, K. M.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snow, S. W.; Snow, J.; Snuverink, J.; Snyder, S.; Soares, M.; Sobie, R.; Sodomka, J.; Soffer, A.; Solans, C. A.; Solar, M.; Solc, J.; Solfaroli Camillocci, E.; Solodkov, A. A.; Solovyanov, O. V.; Soluk, R.; Sondericker, J.; Sopko, V.; Sopko, B.; Sosebee, M.; Sosnovtsev, V. 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C.; Vetterli, M. C.; Vichou, I.; Vickey, T.; Viehhauser, G. H. A.; Villa, M.; Villani, E. G.; Villaplana Perez, M.; Villate, J.; Vilucchi, E.; Vincter, M. G.; Vinek, E.; Vinogradov, V. B.; Viret, S.; Virzi, J.; Vitale, A.; Vitells, O. V.; Vivarelli, I.; Vives Vaques, F.; Vlachos, S.; Vlasak, M.; Vlasov, N.; Vogel, A.; Vokac, P.; Volpi, M.; Volpini, G.; von der Schmitt, H.; von Loeben, J.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobiev, A. P.; Vorwerk, V.; Vos, M.; Voss, R.; Voss, T. T.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vu Anh, T.; Vudragovic, D.; Vuillermet, R.; Vukotic, I.; Wagner, P.; Wahlen, H.; Walbersloh, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wall, R.; Wang, C.; Wang, H.; Wang, J.; Wang, J. C.; Wang, S. M.; Ward, C. P.; Warsinsky, M.; Wastie, R.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, A. T.; Waugh, B. M.; Webel, M.; Weber, J.; Weber, M. D.; Weber, M.; Weber, M. S.; Weber, P.; Weidberg, A. R.; Weingarten, J.; Weiser, C.; Wellenstein, H.; Wells, P. S.; Wen, M.; Wenaus, T.; Wendler, S.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Werth, M.; Werthenbach, U.; Wessels, M.; Whalen, K.; Wheeler-Ellis, S. J.; Whitaker, S. P.; White, A.; White, M. J.; White, S.; Whiteson, D.; Whittington, D.; Wicek, F.; Wicke, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik, L. A. M.; Wildauer, A.; Wildt, M. A.; Wilhelm, I.; Wilkens, H. G.; Williams, E.; Williams, H. H.; Willis, W.; Willocq, S.; Wilson, J. A.; Wilson, M. G.; Wilson, A.; Wingerter-Seez, I.; Winklmeier, F.; Wittgen, M.; Wolter, M. W.; Wolters, H.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wraight, K.; Wright, C.; Wright, D.; Wrona, B.; Wu, S. L.; Wu, X.; Wulf, E.; Xella, S.; Xie, S.; Xie, Y.; Xu, D.; Xu, N.; Yamada, M.; Yamamoto, A.; Yamamoto, S.; Yamamura, T.; Yamanaka, K.; Yamaoka, J.; Yamazaki, T.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, U. K.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yao, Y.; Yasu, Y.; Ye, J.; Ye, S.; Yilmaz, M.; Yoosoofmiya, R.; Yorita, K.; Yoshida, R.; Young, C.; Youssef, S. P.; Yu, D.; Yu, J.; Yu, M.; Yu, X.; Yuan, J.; Yuan, L.; Yurkewicz, A.; Zaidan, R.; Zaitsev, A. M.; Zajacova, Z.; Zambrano, V.; Zanello, L.; Zarzhitsky, P.; Zaytsev, A.; Zeitnitz, C.; Zeller, M.; Zema, P. F.; Zemla, A.; Zendler, C.; Zenin, O.; Zenis, T.; Zenonos, Z.; Zenz, S.; Zerwas, D.; Zevi Della Porta, G.; Zhan, Z.; Zhang, H.; Zhang, J.; Zhang, Q.; Zhang, X.; Zhao, L.; Zhao, T.; Zhao, Z.; Zhemchugov, A.; Zheng, S.; Zhong, J.; Zhou, B.; Zhou, N.; Zhou, Y.; Zhu, C. G.; Zhu, H.; Zhu, Y.; Zhuang, X.; Zhuravlov, V.; Zimmermann, R.; Zimmermann, S.; Zimmermann, S.; Ziolkowski, M.; Zitoun, R.; Živković, L.; Zmouchko, V. V.; Zobernig, G.; Zoccoli, A.; Zur Nedden, M.; Zutshi, V. 2010-12-01 The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps. This leads to an estimated contribution to the constant term of (0.29^{+0.05}_{-0.04})% in the barrel and (0.54^{+0.06}_{-0.04})% in the endcaps. The same data are used to measure the drift velocity of ionization electrons in liquid argon, which is found to be 4.61±0.07 mm/μs at 88.5 K and 1 kV/mm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026529','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026529">Drift and observations in cosmic-ray modulation, 1</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Potgieter, M. S. 1985-01-01 It is illustrated that a relative simple drift model can, in contrast with no drift models, simultaneously fit proton and electron spectra observed in 1965-66 and 1977, using a single set of modulation parameters except for a change in the IMF polarity. This result is interpreted together with the observation of Evenson and Meyer that electrons are recovering more rapidly than protons after 1980, in contrast with what Burger and Swanenburg observed in 1968-72, as a charge sign dependent effect due to the occurrence of drift in cosmic ray modulation. The same set of parameters produces a shift in the phase and amplitude of the diurnal anisotropy vector, consistent with observations in 1969-71 and 1980-81. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130000449','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130000449">Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Okojie, Robert S.; Lukco, Dorothy; Nguyen, Vu; Savrun, Ender 2012-01-01 We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770016278','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770016278">Development of a drift-correction procedure for a direct-reading spectrometer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chapman, G. B., II; Gordon, W. A. 1977-01-01 A procedure which provides automatic correction for drifts in the radiometric sensitivity of each detector channel in a direct-reading emission spectrometer is described. Such drifts are customarily controlled by the regular analyses of standards, which provide corrections for changes in the excitational, optical, and electronic components of the instrument. This standardization procedure, however, corrects for the optical and electronic drifts. It is a step that must be taken if the time, effort, and cost of processing standards is to be minimized. This method of radiometric drift correction uses a 1,000-W tungsten-halogen reference lamp to illuminate each detector through the same optical path as that traversed during sample analysis. The responses of the detector channels to this reference light are regularly compared with channel response to the same light intensity at the time of analytical calibration in order to determine and correct for drift. Except for placing the lamp in position, the procedure is fully automated and compensates for changes in spectral intensity due to variations in lamp current. A discussion of the implementation of this drift-correction system is included. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPhD...47k5203L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhD...47k5203L">Electron transport parameters in NF3</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lisovskiy, V.; Yegorenkov, V.; Ogloblina, P.; Booth, J.-P.; Martins, S.; Landry, K.; Douai, D.; Cassagne, V. 2014-03-01 We present electron transport parameters (the first Townsend coefficient, the dissociative attachment coefficient, the fraction of electron energy lost by collisions with NF3 molecules, the average and characteristic electron energy, the electron mobility and the drift velocity) in NF3 gas calculated from published elastic and inelastic electron-NF3 collision cross-sections using the BOLSIG+ code. Calculations were performed for the combined RB (Rescigno 1995 Phys. Rev. E 52 329, Boesten et al 1996 J. Phys. B: At. Mol. Opt. Phys. 29 5475) momentum-transfer cross-section, as well as for the JB (Joucoski and Bettega 2002 J. Phys. B: At. Mol. Opt. Phys. 35 783) momentum-transfer cross-section. In addition, we have measured the radio frequency (rf) breakdown curves for various inter-electrode gaps and rfs, and from these we have determined the electron drift velocity in NF3 from the location of the turning point in these curves. These drift velocity values are in satisfactory agreement with those calculated by the BOLSIG+ code employing the JB momentum-transfer cross-section. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/24560','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/24560">Propeller wash effects on spray drift</a> <a target="_blank" rel="noopener noreferrer" href="http://www.fs.usda.gov/treesearch/">Treesearch</a> Steven J. Thompson; Alvin R. Womac; Joseph Mulrooney; Sidney Deck 2005-01-01 for aerial spray application, there is some question if off-target drift (both near and far) is influenced by which boom is spraying and the direction of propeller wash rotation. This information may be useful when switching off one boom close to a field boundary. The effect of alternate boom switching and propeller wash direction on aerial spray drift from a turbine-... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989PhFlB...1.1654F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989PhFlB...1.1654F">Stabilization of lower hybrid drift modes by finite parallel wavenumber and electron temperature gradients in field-reversed configurations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Farengo, R.; Guzdar, P. N.; Lee, Y. C. 1989-08-01 The effect of finite parallel wavenumber and electron temperature gradients on the lower hybrid drift instability is studied in the parameter regime corresponding to the TRX-2 device [Fusion Technol. 9, 48 (1986)]. Perturbations in the electrostatic potential and all three components of the vector potential are considered and finite beta electron orbit modifications are included. The electron temperature gradient decreases the growth rate of the instability but, for kz=0, unstable modes exist for ηe(=T'en0/Ten0)>6. Since finite kz effects completely stabilize the mode at small values of kz/ky(≂5×10-3), magnetic shear could be responsible for stabilizing the lower hybrid drift instability in field-reversed configurations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPB10100G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPB10100G">Energy Conversion Mechanism for Electron Perpendicular Energy in High Guide-Field Reconnection</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Guo, Xuehan; Horiuchi, Ritoku; Kaminou, Yasuhiro; Cheng, Frank; Ono, Yasushi 2016-10-01 The energy conversion mechanism for electron perpendicular energy, both the thermal and the kinetic energy, is investigated by means of two-dimensional, full-particle simulations in an open system. It is shown that electron perpendicular heating is mainly due to the breaking of magnetic moment conservation in separatrix region because the charge separation generates intense variation of electric field within the electron Larmor radius. Meanwhile, electron perpendicular acceleration takes place manly due to the polarization drift term as well as the curvature drift term of E . u⊥ in the downstream near the X-point. The enhanced electric field due to the charge separation there results in a significant effect of the polarization drift term on the dissipation of magnetic energy within the ion inertia length in the downstream. Japan Society for the Promotion of Science (JSPS) Fellows 15J03758. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/23666','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/23666">Iowa's cooperative snow fence program.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a> 2005-06-01 While we cant keep it from blowing, there are ways to influence the wind that carries tons : of blowing and drifting snow. Periodically, severe winter storms will create large snow : drifts that close roads and driveways, isolate farmsteads and in... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16057953','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16057953">Continental drift before 1900.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Rupke, N A 1970-07-25 The idea that Francis Bacon and other seventeenth and eighteenth century thinkers first conceived the notion of continental drift does not stand up to close scrutiny. The few authors who expressed the idea viewed the process as a catastrophic event. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981PhLA...84..294R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981PhLA...84..294R">Drift mobility of photo-electrons in organic molecular crystals: Quantitative comparison between theory and experiment</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reineker, P.; Kenkre, V. M.; Kühne, R. 1981-08-01 A quantitative comparison of a simple theoretical prediction for the drift mobility of photo-electrons in organic molecular crystals, calculated within the model of the coupled band-like and hopping motion, with experiments in napthalene of Schein et al. and Karl et al. is given. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA387269','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA387269">Experimental Investigations with a 5-kW-Class Laboratory Model Closed-Drifted Hall Thruster</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2001-01-01 Hall thruster (CDT). The project was composed of the following segments: 1) a 5-kW-class CDT (P5) was built and characterized in terms of performance and plume divergence; 2) the molecular-beam mass spectrometer (MBMS) was used to measure the ion energy distribution finction and charge state throughout the PS plume; 3) laser-induced fluorescence was used to measure the ion velocity and temperature in the near-field plume; 4) a 35 GHz microwave interferometer was developed to measure plasma oscillations and electron density in the plume; and 5) the near-field and internal </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900055519&hterms=difference+engine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddifference%2Bengine','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900055519&hterms=difference+engine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddifference%2Bengine">A review of Soviet plasma engine development</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Barnett, John W. 1990-01-01 The Soviet Union has maintained a substantial and successful electric propulsion research and development effort since the 1950s; however, American researchers are generally unfamiliar with the Soviet accomplishments. Sources of information about Soviet electric propulsion research are noted. The development of plasma engines, a subset of the electric propulsion effort, is reviewed using numerous Soviet sources. The operational principles and status of several engines of the closed electron drift and high-current types are discussed. With recognition of the limited knowledge of the current Soviet program, the Soviet and American programs are compared, revealing some differences in program formulation and emphasis. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750008281','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750008281">The collisional drift mode in a partially ionized plasma. [in the F region</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hudson, M. K.; Kennel, C. F. 1974-01-01 The structure of the drift instability was examined in several density regimes. Let sub e be the total electron mean free path, k sub z the wave-vector component along the magnetic field, and the ratio of perpendicular ion diffusion to parallel electron streaming rates. At low densities (k sub z lambda 1) the drift mode is isothermal and should be treated kineticly. In the finite heat conduction regime square root of m/M k sub z Lambda sub 1) the drift instability threshold is reduced at low densities and increased at high densities as compared to the isothermal threshold. Finally, in the energy transfer limit (k sub z kambda sub e square root of m/M) the drift instability behaves adiabatically in a fully ionized plasma and isothermally in a partially ionized plasma for an ion-neutral to Coulomb collision frequency ratio. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA16570.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA16570.html">Windblown Sand from the Rocknest Drift</a> <a target="_blank" rel="noopener noreferrer" href="https://images.nasa.gov/">NASA Image and Video Library</a> 2012-12-03 NASA Mars rover Curiosity acquired close-up views of sands in the Rocknest wind drift to document the nature of the material that the rover scooped, sieved and delivered to the CheMin and SAM instruments in October and November 2012. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JSP...171..656S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JSP...171..656S">Random Walk on a Perturbation of the Infinitely-Fast Mixing Interchange Process</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Salvi, Michele; Simenhaus, François 2018-05-01 We consider a random walk in dimension d≥ 1 in a dynamic random environment evolving as an interchange process with rate γ >0. We prove that, if we choose γ large enough, almost surely the empirical velocity of the walker X_t/t eventually lies in an arbitrary small ball around the annealed drift. This statement is thus a perturbation of the case γ =+∞ where the environment is refreshed between each step of the walker. We extend three-way part of the results of Huveneers and Simenhaus (Electron J Probab 20(105):42, 2015), where the environment was given by the 1-dimensional exclusion process: (i) We deal with any dimension d≥1; (ii) We treat the much more general interchange process, where each particle carries a transition vector chosen according to an arbitrary law μ ; (iii) We show that X_t/t is not only in the same direction of the annealed drift, but that it is also close to it. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/166285-effect-wave-particle-interactions-polar-wind-sup','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/166285-effect-wave-particle-interactions-polar-wind-sup">The effect of wave-particle interactions on the polar wind O{sup +}</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Barakat, A.R.; Barghouthi, I.A. 1994-10-15 The escape of the polar wind plasma is an important element in the ionosphere-magnetosphere coupling. Both theory and observations indicate that the wave-particle interactions (WPI) play a significant role in the dynamics of ion outflow along open geomagnetic field lines. A Monte Carlo simulation was developed in order to include the effect of the WPI in addition to the factors that are traditionally included in the {open_quote}classical{close_quote} polar wind (i.e. gravity, electrostatic field, and divergence of geomagnetic field lines). The ion distribution function (f{sub j}), as well as the profiles of its moments (density, drift velocity, temperature, etc.) were foundmore » for different levels of WPI, that is, for different values of the normalized diffusion rate in the velocity space (D{sub {perpendicular}{sub j}}). Although the model included O{sup +}, H{sup +} and electrons, the authors presented only the results related to the O{sup +} ions. They found that (1) both the density and drift velocity of O{sup +} increased with the WPI strength, and consequently, the O{sup +} escape flux was enhanced by a factor of up to 10{sup 5}; (2) The O{sup +} ions could be energized up to a few electron volts; (3) for moderate and high levels of WPI (D{sub {perpendicular}}(O{sup +})>1), the distribution function f(O{sup +}) displayed very pronounced conic features at altitudes around 3R{sub E}. Finally, the interplay between the downward body force, the upward mirror force, and the perpendicular heating resulted in the formation of the {open_quotes}pressure cooker{close_quotes} effect. This phenomena explained some interesting features of their solution, such as, the peak in the O{sup +} temperature, and the formation of {open_quotes}ears{close_quotes} and conics for f(O{sup +}) around 2.5R{sub E}. 10 refs., 2 figs.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018FrPhy..13.7203D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018FrPhy..13.7203D">Electron drift velocity and mobility in graphene</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dong, Hai-Ming; Duan, Yi-Feng; Huang, Fei; Liu, Jin-Long 2018-04-01 We present a theoretical study of the electric transport properties of graphene-substrate systems. The drift velocity, mobility, and temperature of the electrons are self-consistently determined using the Boltzmann equilibrium equations. It is revealed that the electronic transport exhibits a distinctly nonlinear behavior. A very high mobility is achieved with the increase of the electric fields increase. The electron velocity is not completely saturated with the increase of the electric field. The temperature of the hot electrons depends quasi-linearly on the electric field. In addition, we show that the electron velocity, mobility, and electron temperature are sensitive to the electron density. These findings could be employed for the application of graphene for high-field nano-electronic devices. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860044251&hterms=formation+day+night&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dformation%2Bday%2Bnight','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860044251&hterms=formation+day+night&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dformation%2Bday%2Bnight">The effect of vertical drift on the equatorial F-region stability</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hanson, W. B.; Cragin, B. L.; Dennis, A. 1986-01-01 Time-dependent ionospheric model calculations for day-time and night-time solutions are presented. The behavior of the growth rate and ion-electron recombination rate for the Rayleigh-Taylor instability on the F-region bottomside is examined as a function of the vertical eastward electric field-magnetic field strength drift velocity. It is observed that on the bottomside F-layer the growth rate exceeds the ion-electron recombination rate even without vertical drift; however, an eastward electric field-magnetic field strength drift can produce an increase in the growth rate by an order of magnitude. The calculated data are compared with previous research and good correlation is detected. The formation of bubbles from a seeding mechanism is investigated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1353176-measurement-drift-velocity-transverse-diffusion-electrons-liquid-xenon-exo-detector','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1353176-measurement-drift-velocity-transverse-diffusion-electrons-liquid-xenon-exo-detector">Measurement of the drift velocity and transverse diffusion of electrons in liquid xenon with the EXO-200 detector</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Albert, J. B.; Barbeau, P. S.; Beck, D.; ... 2017-02-14 The EXO-200 Collaboration is searching for neutrinoless double β decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the transport of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. In this paper, we present measurements of the transverse diffusion constant and drift velocity of electrons at drift fields between 20 V/cm and 615 V/cm using EXO-200 data. Finally, at the operating field of 380 V/cm EXO-200 measures a drift velocity of 1.705 +0.014 –0.010 mm/μs and a transverse diffusion coefficient of 55 ± 4 cm 2/s. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active">6</li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active">7</li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33A2764T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33A2764T">Electron bulk speed lags the protons in the collisionless solar wind</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tong, Y.; Bale, S. D.; Salem, C. S.; Pulupa, M. 2017-12-01 We use a large, statistical set of in situ measurements of the solar wind electron distribution from the Wind/3DP instrument to show that the magnetic field-aligned core electron-proton drift speed tend to small values at high collisionality and asymptotes towards a large limiting value in the collisionless limit. This collisionless drift-limit, when normalized to the local Alfven speed is large and may drive instabilities. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......457K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......457K">Measurements verifying the optics of the Electron Drift Instrument</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kooi, Vanessa M. This thesis concentrates on laboratory measurements of the Electron Drift Instrument (EDI), focussing primarily on the EDI optics of the system. The EDI is a device used on spacecraft to measure electric fields by emitting an electron beam and measuring the E x B drift of the returning electrons after one gyration. This drift velocity is determined using two electron beams directed perpendicular to the magnetic field returning to be detected by the spacecraft. The EDI will be used on the Magnetospheric Multi-Scale Mission. The EDI optic's testing process takes measurements of the optics response to a uni-directional electron beam. These measurements are used to verify the response of the EDI's optics and to allow for the optimization of the desired optics state via simulation. The optics state tables were created in simulations and we are using these measurements to confirm their accuracy. The setup consisted of an apparatus made up of the EDI's optics and sensor electronics was secured to the two axis gear arm inside a vacuum chamber. An electron beam was projected at the apparatus which then used the EDI optics to focus the beam into the micro-controller plates and onto the circular 32 pad annular ring that makes up the sensor. The concentration of counts per pad over an interval of 1ms were averaged over 25 samples and plotted in MATLAB. The results of the measurements plotted agreed well with the simulations, providing confidence in the EDI instrument. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26835637','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26835637">Analysis of dead zone sources in a closed-loop fiber optic gyroscope.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Chong, Kyoung-Ho; Choi, Woo-Seok; Chong, Kil-To 2016-01-01 Analysis of the dead zone is among the intensive studies in a closed-loop fiber optic gyroscope. In a dead zone, a gyroscope cannot detect any rotation and produces a zero bias. In this study, an analysis of dead zone sources is performed in simulation and experiments. In general, the problem is mainly due to electrical cross coupling and phase modulation drift. Electrical cross coupling is caused by interference between modulation voltage and the photodetector. The cross-coupled signal produces spurious gyro bias and leads to a dead zone if it is larger than the input rate. Phase modulation drift as another dead zone source is due to the electrode contamination, the piezoelectric effect of the LiNbO3 substrate, or to organic fouling. This modulation drift lasts for a short or long period of time like a lead-lag filter response and produces gyro bias error, noise spikes, or dead zone. For a more detailed analysis, the cross-coupling effect and modulation phase drift are modeled as a filter and are simulated in both the open-loop and closed-loop modes. The sources of dead zone are more clearly analyzed in the simulation and experimental results. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..11612217D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..11612217D">Convective and diffusive ULF wave driven radiation belt electron transport</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Degeling, A. W.; Rankin, R.; Elkington, S. R. 2011-12-01 The process of magnetospheric radiation belt electron transport driven by ULF waves is studied using a 2-D ideal MHD model for ULF waves in the equatorial plane including day/night asymmetry and a magnetopause boundary, and a test kinetic model for equatorially mirroring electrons. We find that ULF wave disturbances originating along the magnetopause flanks in the afternoon sector can act to periodically inject phase space density from these regions into the magnetosphere. Closely spaced drift-resonant surfaces for electrons with a given magnetic moment in the presence of the ULF waves create a layer of stochastic dynamics for L-shells above 6.5-7 in the cases examined, extending to the magnetopause. The phase decorrelation time scale for the stochastic region is estimated by the relaxation time for the diffusion coefficient to reach a steady value. This is found to be of the order of 10-15 wave periods, which is commensurate with the typical duration of observed ULF wave packets in the magnetosphere. For L-shells earthward of the stochastic layer, transport is limited to isolated drift-resonant islands in the case of narrowband ULF waves. We examine the effect of increasing the bandwidth of the ULF wave driver by summing together wave components produced by a set of independent runs of the ULF wave model. The wave source spectrum is given a flat-top amplitude of variable width (adjusted for constant power) and random phase. We find that increasing bandwidth can significantly enhance convective transport earthward of the stochastic layer and extend the stochastic layer to lower L-shells. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPYI2006L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPYI2006L">New insights on boundary plasma turbulence and the Quasi-Coherent Mode in Alcator C-Mod using a Mirror Langmuir Probe</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Labombard, Brian 2013-10-01 A ``Mirror Langmuir Probe'' (MLP) diagnostic has been used to interrogate edge plasma profiles and turbulence in Alcator C-Mod with unprecedented detail, yielding fundamental insights on the Quasi-Coherent Mode (QCM) - a mode that regulates plasma density and impurities in EDA H-modes without ELMs. The MLP employs a fast-switching, self-adapting bias scheme, recording density, electron temperature and plasma potential simultaneously at high bandwidth (~1 MHz) on each of four separate electrodes on a scanning probe. Temporal dynamics are followed in detail; wavenumber-frequency spectra and phase relationships are readily deduced. Poloidal field fluctuations are recorded separately with a two-coil, scanning probe. Results from ohmic L-mode and H-mode plasmas are reported, including key observations of the QCM: The QCM lives in a region of positive radial electric field, with a mode width (~3 mm) that spans open and closed field line regions. Remarkably large amplitude (~30%), sinusoidal bursts in density, electron temperature and plasma potential fluctuations are observed that are in phase; potential lags density by at most 10 degrees. Propagation velocity of the mode corresponds to the sum of local E × B and electron diamagnetic drift velocities - quantities that are deduced directly from time-averaged profiles. Poloidal magnetic field fluctuations project to parallel current densities of ~5 amps/cm2 in the mode layer, with significant parallel electromagnetic induction. Electron force balance is examined, unambiguously identifying the mode type. It is found that fluctuations in parallel electron pressure gradient are roughly balanced by the sum of electrostatic and electromotive forces. Thus the primary mode structure of the QCM is that of a drift-Alfven wave. Work supported by US DoE award DE-FC02-99ER54512. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19672760','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19672760">Spray droplet size, drift potential, and risks to nontarget organisms from aerially applied glyphosate for coca control in Colombia.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Hewitt, Andrew J; Solomon, Keith R; Marshall, E J P 2009-01-01 A wind tunnel atomization study was conducted to measure the emission droplet size spectra for water and Glyphos (a glyphosate formulation sold in Colombia) + Cosmo-flux sprays for aerial application to control coca and poppy crops in Colombia. The droplet size spectra were measured in a wind tunnel for an Accu-Flo nozzle (with 16 size 0.085 [2.16 mm] orifices), under appropriate simulated aircraft speeds (up to 333 km/h), using a laser diffraction instrument covering a dynamic size range for droplets of 0.5 to 3,500 microm. The spray drift potential of the glyphosate was modeled using the AGDISP spray application and drift model, using input parameters representative of those occurring in Colombia for typical aerial application operations. The droplet size spectra for tank mixes containing glyphosate and Cosmo-Flux were considerably finer than water and became finer with higher aircraft speeds. The tank mix with 44% glyphosate had a D(v0.5) of 128 microm, while the value at the 4.9% glyphosate rate was 140 microm. These are classified as very fine to fine sprays. Despite being relatively fine, modeling showed that the droplets would not evaporate as rapidly as most similarly sized agricultural sprays because the nonvolatile proportion of the tank mix (active and inert adjuvant ingredients) was large. Thus, longer range drift is small and most drift that does occur will deposit relatively close to the application area. Drift will only occur downwind and, with winds of velocity less than the modeled maximum of 9 km/h, the drift distance would be substantially reduced. Spray drift potential might be additionally reduced through various practices such as the selection of nozzles, tank mix adjuvants, aircraft speeds, and spray pressures that would produce coarser sprays. Species sensitivity distributions to glyphosate were constructed for plants and amphibians. Based on modeled drift and 5th centile concentrations, appropriate no-spray buffer zones (distance from the end of the spray boom as recorded electronically +/-5%) for protection of sensitive plants were 50-120 m for coca spray scenarios and considerably lower for poppy spray scenarios. The equivalent buffer zone for amphibia was 5 m. The low toxicity of glyphosate to humans suggests that these aerial applications are not a concern for human health. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1345495-kinetic-neoclassical-transport-mode-pedestal','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1345495-kinetic-neoclassical-transport-mode-pedestal">Kinetic neoclassical transport in the H-mode pedestal</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Battaglia, D. J.; Burrell, K. H.; Chang, C. S.; ... 2014-07-16 Multi-species kinetic neoclassical transport through the QH-mode pedestal and scrapeoff layer on DIII-D is calculated using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. We achieved quantitative agreement between the fluxdriven simulation and the experimental electron density, impurity density and orthogonal measurements of impurity temperature and flow profiles by adding random-walk particle diffusion to the guiding-center drift motion. Furthermore, we computed the radial electric field (Er) that maintains ambipolar transport across flux surfaces and to the wall self-consistently on closed and open magnetic field lines, and is in excellent agreement with experiment. The Ermore » inside the separatrix is the unique solution that balances the outward flux of thermal tail deuterium ions against the outward neoclassical electron flux and inward pinch of impurity and colder deuterium ions. Particle transport in the pedestal is primarily due to anomalous transport, while the ion heat and momentum transport is primarily due to the neoclassical transport. The full-f treatment quantifies the non-Maxwellian energy distributions that describe a number of experimental observations in low-collisionallity pedestals on DIII-D, including intrinsic co-Ip parallel flows in the pedestal, ion temperature anisotropy and large impurity temperatures in the scrape-off layer.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6873735-experimental-study-propagation-intense-relativistic-electron-beams-nonconducting-vacuum-drift-tubes-after-passage-through-localized-plasma-source','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6873735-experimental-study-propagation-intense-relativistic-electron-beams-nonconducting-vacuum-drift-tubes-after-passage-through-localized-plasma-source">Experimental study of propagation of intense relativistic electron beams in nonconducting vacuum drift tubes after passage through a localized plasma source</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Destler, W.W.; O'Shea, P.G.; Segalov, Z. 1987-04-01 The propagation of intense relativistic electron beams into evacuated nonconducting drift tubes after passage through a localized plasma source has been experimentally studied. Time-integrated photographs of the propagation process have been obtained, as well as quantitative measurements of the propagated beam current and energy. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1338751-formation-energetic-electron-butterfly-distributions-magnetosonic-waves-via-landau-resonance','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1338751-formation-energetic-electron-butterfly-distributions-magnetosonic-waves-via-landau-resonance">Formation of energetic electron butterfly distributions by magnetosonic waves via Landau resonance</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Li, Jinxing; Ni, Binbin; Ma, Qianli; ... 2016-03-06 Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90°, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been resolved. In this study, by analyzing the particle and wave data collected by the Van Allen Probes during a geomagnetic storm, we combinemore » test particle calculations and Fokker-Planck simulations to reveal that scattering by equatorial magnetosonic waves is a significant cause for the formation of energetic electron butterfly distributions in the inner magnetosphere. Finally, another event shows that a large-amplitude magnetosonic wave in the outer belt can create electron butterfly distributions in just a few minutes.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12210036H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12210036H">Simulated Prompt Acceleration of Multi-MeV Electrons by the 17 March 2015 Interplanetary Shock</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hudson, Mary; Jaynes, Allison; Kress, Brian; Li, Zhao; Patel, Maulik; Shen, Xiao-Chen; Thaller, Scott; Wiltberger, Michael; Wygant, John 2017-10-01 Prompt enhancement of relativistic electron flux at L = 3-5 has been reported from Van Allen Probes Relativistic Electron Proton Telescope (REPT) measurements associated with the 17 March 2015 interplanetary shock compression of the dayside magnetosphere. Acceleration by ˜1 MeV is inferred on less than a drift timescale as seen in prior shock compression events, which launch a magnetosonic azimuthal electric field impulse tailward. This impulse propagates from the dayside around the flanks accelerating electrons in drift resonance at the dusk flank. Such longitudinally localized acceleration events produce a drift echo signature which was seen at >1 MeV energy on both Van Allen Probe spacecraft, with sustained observations by Probe B outbound at L = 5 at 2100 MLT at the time of impulse arrival, measured by the Electric Fields and Waves instrument. MHD test particle simulations are presented which reproduce drift echo features observed in the REPT measurements at Probe B, including the energy and pitch angle dependence of drift echoes observed. While the flux enhancement was short lived for this event due to subsequent inward motion of the magnetopause, stronger events with larger electric field impulses, as observed in March 1991 and the Halloween 2003 storm, produce enhancements which can be quantified by the inward radial transport and energization determined by the induction electric field resulting from dayside compression. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990110677&hterms=ccc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dccc','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990110677&hterms=ccc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dccc">Effects of Convection Electric Fields on Modeled Plasmaspheric Densities and ccc Temperatures</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Comfort, Richard H.; Richards, Phil G.; Liao, Jin-Hua; Craven, Paul D. 1998-01-01 This paper examines the effects of convection electric fields on plasmaspheric H+, O+, He+, and N+ densities and electron and ion temperatures. These effects are studied with the aid of the Field Line Interhemispheric Plasma (FLIP) model, which has recently been extended to include the effects of ExB drifts. The FLIP model solves the continuity and momentum equations for the major ion species as well as the energy equations for ions and electrons along entire drifting flux tubes from 100 km altitude in the northern hemisphere to 100 km altitude in the southern hemisphere. Electron heating in the ionosphere and plasmasphere is provided by the solution of two-stream equations for photoelectrons. The dawn-dusk electric field imposed by the solar wind causes changes in plasmaspheric density and temperature as the plasma drifts onto flux tubes having different volumes. In an idealized convection model, outward drifts in the afternoon cause decreases in the plasmasphere density and temperature while inward drifts in the evening cause increases in plasmasphere density and temperature. In this paper we examine the effects of convection electric fields on the rate of refilling of flux tubes and investigate the hypothesis that convection electric fields are responsible for the unusually high evening electron temperatures and the post-midnight density maxima often observed in the winter ionosphere above Millstone Hill. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1407091-drift-time-measurement-atlas-liquid-argon-electromagnetic-calorimeter-using-cosmic-muons','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1407091-drift-time-measurement-atlas-liquid-argon-electromagnetic-calorimeter-using-cosmic-muons">Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic Calorimeter using Cosmic Muons</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Aad, G.; Abbott, B.; Abdallah, J.; ... 2010-10-23 The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps. This leads to an estimated contribution to the constant term of (0.29more » $$+0.05\\atop{-0.04}$$) % in the barrel and (0.54$$+0.06\\atop{-0.04}$$)% in the endcaps. Lastly, the same data are used to measure the drift velocity of ionization electrons in liquid argon, which is found to be 4.61 ± 0.07 mm/μs at 88.5 K and 1 kV/mm.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RaSc...51.1263C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RaSc...51.1263C">A technique for inferring zonal irregularity drift from single-station GNSS measurements of intensity (S4) and phase (σφ) scintillations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Carrano, Charles S.; Groves, Keith M.; Rino, Charles L.; Doherty, Patricia H. 2016-08-01 The zonal drift of ionospheric irregularities at low latitudes is most commonly measured by cross-correlating observations of a scintillating satellite signal made with a pair of closely spaced antennas. The Air Force Research Laboratory-Scintillation Network Decision Aid (AFRL-SCINDA) network operates a small number of very high frequency (VHF) spaced-receiver systems at low latitudes for this purpose. A far greater number of Global Navigation Satellite System (GNSS) scintillation monitors are operated by the AFRL-SCINDA network (25-30) and the Low-Latitude Ionospheric Sensor Network (35-50), but the receivers are too widely separated from each other for cross-correlation techniques to be effective. In this paper, we present an alternative approach that leverages the weak scatter scintillation theory to infer the zonal irregularity drift from single-station GNSS measurements of S4, σφ, and the propagation geometry. Unlike the spaced-receiver technique, this approach requires assumptions regarding the height of the scattering layer (which introduces a bias in the drift estimates) and the spectral index of the irregularities (which affects the spread of the drift estimates about the mean). Nevertheless, theory and experiment suggest that the ratio of σφ to S4 is less sensitive to these parameters than it is to the zonal drift. We validate the technique using VHF spaced-receiver measurements of zonal irregularity drift obtained from the AFRL-SCINDA network. While the spaced-receiver technique remains the preferred way to monitor the drift when closely spaced antenna pairs are available, our technique provides a new opportunity to monitor zonal irregularity drift using regional or global networks of widely separated GNSS scintillation monitors. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22649747-field-dependence-electron-drift-velocity-along-hexagonal-axis-sic','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22649747-field-dependence-electron-drift-velocity-along-hexagonal-axis-sic">Field dependence of the electron drift velocity along the hexagonal axis of 4H-SiC</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ivanov, P. A., E-mail: Pavel.Ivanov@mail.ioffe.ru; Potapov, A. S.; Samsonova, T. P. The forward current–voltage characteristics of mesa-epitaxial 4H-SiC Schottky diodes are measured in high electric fields (up to 4 × 10{sup 5} V/cm) in the n-type base region. A semi-empirical formula for the field dependence of the electron drift velocity in 4H-SiC along the hexagonal axis of the crystal is derived. It is shown that the saturated drift velocity is (1.55 ± 0.05) × 10{sup 7} cm/s in electric fields higher than 2 × 10{sup 5} V/cm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/285572-transport-toroidally-confined-pure-electron-plasma','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/285572-transport-toroidally-confined-pure-electron-plasma">Transport in a toroidally confined pure electron plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Crooks, S.M.; ONeil, T.M. 1996-07-01 O{close_quote}Neil and Smith [T.M. O{close_quote}Neil and R.A. Smith, Phys. Plasmas {bold 1}, 8 (1994)] have argued that a pure electron plasma can be confined stably in a toroidal magnetic field configuration. This paper shows that the toroidal curvature of the magnetic field of necessity causes slow cross-field transport. The transport mechanism is similar to magnetic pumping and may be understood by considering a single flux tube of plasma. As the flux tube of plasma undergoes poloidal {ital E}{bold {times}}{ital B} drift rotation about the center of the plasma, the length of the flux tube and the magnetic field strength withinmore » the flux tube oscillate, and this produces corresponding oscillations in {ital T}{sub {parallel}} and {ital T}{sub {perpendicular}}. The collisional relaxation of {ital T}{sub {parallel}} toward {ital T}{sub {perpendicular}} produces a slow dissipation of electrostatic energy into heat and a consequent expansion (cross-field transport) of the plasma. In the limit where the cross section of the plasma is nearly circular the radial particle flux is given by {Gamma}{sub {ital r}}=1/2{nu}{sub {perpendicular},{parallel}}{ital T}({ital r}/{rho}{sub 0}){sup 2}{ital n}/({minus}{ital e}{partial_derivative}{Phi}/{partial_derivative}{ital r}), where {nu}{sub {perpendicular},{parallel}} is the collisional equipartition rate, {rho}{sub 0} is the major radius at the center of the plasma, and {ital r} is the minor radius measured from the center of the plasma. The transport flux is first calculated using this simple physical picture and then is calculated by solving the drift-kinetic Boltzmann equation. This latter calculation is not limited to a plasma with a circular cross section. {copyright} {ital 1996 American Institute of Physics.}« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10625777G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10625777G">A tale of two theories: How the adiabatic response and ULF waves affect relativistic electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Green, J. C.; Kivelson, M. G. 2001-11-01 Using data from the Comprehensive Energetic Particle and Pitch Angle Distribution (CEPPAD)-High Sensitivity Telescope (HIST) instrument on the Polar spacecraft and ground magnetometer data from the 210 meridian magnetometer chain, we test the ULF wave drift resonance theory proposed to explain relativistic electron phase space density enhancements. We begin by investigating changes in electron flux due to the ``Dst effect.'' The Dst effect refers to the adiabatic response of relativistic electrons to changes in the magnetic field characterized by the Dst index. The Dst effect, assuming no loss or addition of new electrons, produces reversible order of magnitude changes in relativistic electrons flux measured at fixed energy, but it cannot account for the flux enhancement that occurs in the recovery phase of most storms. Liouville's theorem states that phase space density expressed in terms of constant adiabatic invariants is unaffected by adiabatic field changes and thus is insensitive to the Dst effect. It is therefore useful to express flux measurements in terms of phase space densities at constant first, second and third adiabatic invariants. The phase space density is determined from the CEPPAD-HIST electron detector that measures differential directional flux of electrons from 0.7 to 9 MeV and the Tsyganenko 96 field model. The analysis is done for January to June 1997. The ULF wave drift resonance theory that we test proposes that relativistic electrons are accelerated by an m=2 toroidal or poloidal mode wave whose frequency equals the drift frequency of the electron. The theory is tested by comparing the relativistic electron phase space densities to wave power determined at three ground stations with L* values of 4.0, 5.7 and 6.2. Comparison of the wave data to the phase space densities shows that five out of nine storm events are consistent with the ULF wave drift resonance mechanism, three out of nine give ambiguous support to the model, and one event has high ULF wave power at the drift frequency of the electrons but no corresponding phase space density enhancement suggesting that ULF wave power alone is not sufficient to cause an electron response. Two explanations of the anomalous event are investigated including excessive loss of electrons to the magnetopause and wave duration. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22472011-transportation-high-current-ion-electron-beams-accelerator-drift-gap-presence-additional-electron-background','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22472011-transportation-high-current-ion-electron-beams-accelerator-drift-gap-presence-additional-electron-background">Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Karas’, V. I., E-mail: karas@kipt.kharkov.ua; Kornilov, E. A.; Manuilenko, O. V. 2015-12-15 The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov–Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and inmore » the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PlPhR..41.1028K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PlPhR..41.1028K">Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Karas', V. I.; Kornilov, E. A.; Manuilenko, O. V.; Tarakanov, V. P.; Fedorovskaya, O. V. 2015-12-01 The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov-Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/989332','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/989332">Large Time Projection Chambers for Rare Event Detection</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Heffner, M The Time Projection Chamber (TPC) concept [add ref to TPC section] has been applied to many projects outside of particle physics and the accelerator based experiments where it was initially developed. TPCs in non-accelerator particle physics experiments are principally focused on rare event detection (e.g. neutrino and darkmater experiments) and the physics of these experiments can place dramatically different constraints on the TPC design (only extensions to the traditional TPCs are discussed here). The drift gas, or liquid, is usually the target or matter under observation and due to very low signal rates a TPC with the largest active massmore » is desired. The large mass complicates particle tracking of short and sometimes very low energy particles. Other special design issues include, efficient light collection, background rejection, internal triggering and optimal energy resolution. Backgrounds from gamma-rays and neutrons are significant design issues in the construction of these TPCs. They are generally placed deep underground to shield from cosmogenic particles and surrounded with shielding to reduce radiation from the local surroundings. The construction materials have to be carefully screened for radiopurity as they are in close contact with the active mass and can be a signification source of background events. The TPC excels in reducing this internal background because the mass inside the fieldcage forms one monolithic volume from which fiducial cuts can be made ex post facto to isolate quiet drift mass, and can be circulated and purified to a very high level. Self shielding in these large mass systems can be significant and the effect improves with density. The liquid phase TPC can obtain a high density at low pressure which results in very good self-shielding and compact installation with a lightweight containment. The down sides are the need for cryogenics, slower charge drift, tracks shorter than the typical electron diffusion, lower energy resolution (e.g. xenon) and limited charge readout options. Slower charge drift requires long electron lifetimes placing strict limits on the oxygen and other impurities with high electron affinity. A significant variation of the liquid phase TPC, that improves the charge readout, is the dual-phase TPC where a gas phase layer is formed above the liquid into which the drifting electrons are extracted and amplified, typically with electroluminescence. The successful transfer of electrons through the phase boundary requires careful control of its position and setting up an appropriate electric field. A high pressure gas phase TPC has no cryogenics and density is easily optimized for the signal, but a large heavy pressure vessel is required. Although shelf shielding is reduced, it can in some cases approach that of the liquid phase; in xenon at 50atm the density is about half that of water or about 1/6 of liquid xenon. A significant feature of high pressure xenon gas is the energy resolution. Below a density of about 0.5g/cc the intrinsic resolution is only a few times that of high purity germanium. A neutrino-less double beta decay (0{nu}2{beta}) TPC operated below this density limit could enjoy excellent energy resolution and maintain particle tracking for background rejection. An observable interaction with the TPC results in a charged particle that travels in the drift matter exciting and ionizing the atoms until the initial energy is converted into ionization, scintillation, or heat with relatively large fluctuations around a mean distribution. Rare event TPCs can be designed to detect scintillation light as well as charge to exploit the anti-correlation to improve energy resolution and/or signal to noise. An electric drift field separates the electrons and positive ions from the ionization although the separation is not complete and some electrons are captured, exciting atoms and releasing more light than the primary excitation alone. The average partition between the scintillation and ionization can be manipulated to increase the ionization (at a loss of scintillation) by a number of methods such as, increasing the strength of the electric field up to a saturation of the ionization yield, increasing the temperature to enhance the diffusion of the ionized electrons, and adding dopants such as triethylamine that can be photoionized by the scintillation photons releasing more ionization. Scintillation light is typically collected with photomultiplier tubes (PMTs) and avalanche photo diodes (APDs) although any fast (compared to the ionization drift speed) light collector capable of detecting the typically UV photons, maintaining high radiopurity and perhaps withstanding pressure would work. CCDs are slow and therefore only record 2 dimensions integrating over the time direction, some of which can be recovered with a few PMTs.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DNP.ED011M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DNP.ED011M">T-Violation experiment using polarized Li-8 at TRIUMF</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Murata, Jiro; MTV Collaboration 2014-09-01 The MTV experiment searching T-Violating electron transverse polarization in polarized nuclear beta decay at TRIUMF is running. The main electron tracking detector as a Mott polarimeter was upgraded from a planer drift chamber to a cylindrical drift chamber (CDC), which has been commissioned and tested. In this talk, preparation status of the next physics production using the CDC will be presented. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active">7</li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active">8</li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24d3102W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24d3102W">Conceptual designs of E × B multistage depressed collectors for gyrotrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wu, Chuanren; Pagonakis, Ioannis Gr.; Gantenbein, Gerd; Illy, Stefan; Thumm, Manfred; Jelonnek, John 2017-04-01 Multistage depressed collectors are challenges for high-power, high-frequency fusion gyrotrons. Two concepts exist in the literature: (1) unwinding the spent electron beam cyclotron motion utilizing non-adiabatic transitions of magnetic fields and (2) sorting and collecting the electrons using the E × B drift. To facilitate the collection by the drift, the hollow electron beam can be transformed to one or more thin beams before applying the sorting. There are many approaches, which can transform the hollow electron beam to thin beams; among them, two approaches similar to the tilted electric field collectors of traveling wave tubes are conceptually studied in this paper: the first one transforms the hollow circular electron beam to an elongated elliptic beam, and then the thin elliptic beam is collected by the E × B drift; the second one splits an elliptic or a circular electron beam into two arc-shaped sheet beams; these two parts are collected individually. The functionality of these concepts is proven by CST simulations. A model of a three-stage collector for a 170 GHz, 1 MW gyrotron using the latter approach shows 76% collector efficiency while taking secondary electrons and realistic electron beam characteristics into account. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AnGeo..26.3395U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AnGeo..26.3395U">The electron drift velocity, ion acoustic speed and irregularity drifts in high-latitude E-region</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Uspensky, M. V.; Pellinen, R. J.; Janhunen, P. 2008-10-01 The purpose of this study is to examine the STARE irregularity drift velocity dependence on the EISCAT line-of-sight (los or l-o-s) electron drift velocity magnitude, VE×Blos, and the flow angle ΘN,F (superscript N and/or F refer to the STARE Norway and Finland radar). In the noon-evening sector the flow angle dependence of Doppler velocities, VirrN,F, inside and outside the Farley-Buneman (FB) instability cone (|VE×Blos|>Cs and |VE×Blos|<Cs, respectively, where Cs is the ion acoustic speed), is found to be similar and much weaker than suggested earlier. In a band of flow angles 45°<ΘN,F<85° it can be reasonably described by |VirrN,F|∝AN,FCscosnΘN,F, where AN,F≍1.2 1.3 are monotonically increasing functions of VE×B and the index n is ~0.2 or even smaller. This study (a) does not support the conclusion by Nielsen and Schlegel (1985), Nielsen et al. (2002, their #[18]) that at flow angles larger than ~60° (or |VirrN,F|≤300 m/s) the STARE Doppler velocities are equal to the component of the electron drift velocity. We found (b) that if the data points are averages over 100 m/s intervals (bins) of l-o-s electron velocities and 10 deg intervals (bins) of flow angles, then the largest STARE Doppler velocities always reside inside the bin with the largest flow angle. In the flow angle bin 80° the STARE Doppler velocity is larger than its driver term, i.e. the EISCAT l-o-s electron drift velocity component, |VirrN,F|>|VE×Blos|. Both features (a and b) as well as the weak flow angle velocity dependence indicate that the l-o-s electron drift velocity cannot be the sole factor which controls the motion of the backscatter ~1-m irregularities at large flow angles. Importantly, the backscatter was collected at aspect angle ~1° and flow angle Θ>60°, where linear fluid and kinetic theories invariably predict negative growth rates. At least qualitatively, all the facts can be reasonably explained by nonlinear wave-wave coupling found and described by Kudeki and Farley (1989), Lu et al. (2008) for the equatorial electrojet and studied in numerical simulation by Otani and Oppenheim (1998, 2006). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1402659','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1402659">Effects of ULF waves on local and global energetic particles: Particle energy and species dependences</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Li, L. Y.; Yu, J.; Cao, J. B. After 06:13 UT on 24 August 2005, an interplanetary shock triggers large-amplitude ultralow-frequency (ULF) waves (|δB| ≥ 15 nT) in the Pc4–Pc5 wave band (1.6–9 mHz) near the noon geosynchronous orbit (6.6 RE). The local and global effects of ULF waves on energetic particles are observed by five Los Alamos National Laboratory satellites at different magnetic local times. The large-amplitude ULF waves cause the synchronous oscillations of energetic electrons and protons (≥75 keV) at the noon geosynchronous orbit. When the energetic particles have a negative phase space density radial gradient, they undergo rapid outward radial diffusion and loss in themore » wave activity region. In the particle drift paths without strong ULF waves, only the rapidly drifting energetic electrons (≥225 keV) display energy-dispersive oscillations and flux decays, whereas the slowly drifting electrons (<225 keV) and protons (75–400 keV) have no ULF oscillation and loss feature. When the dayside magnetopause is compressed to the geosynchronous orbit, most of energetic electrons and protons are rapidly lost because of open drift trajectories. Furthermore, the global and multicomposition particle measurements demonstrate that the effect of ULF waves on nonlocal particle flux depends on the particle energy and species, whereas magnetopause shadowing effect is independent of the energetic particle species. For the rapidly drifting outer radiation belt particles (≥225 keV), nonlocal particle loss/acceleration processes could also change their fluxes in the entire drift trajectory in the absence of “ Dst effect” and substorm injection.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1402659-effects-ulf-waves-local-global-energetic-particles-particle-energy-species-dependences','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1402659-effects-ulf-waves-local-global-energetic-particles-particle-energy-species-dependences">Effects of ULF waves on local and global energetic particles: Particle energy and species dependences</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Li, L. Y.; Yu, J.; Cao, J. B.; ... 2016-11-05 After 06:13 UT on 24 August 2005, an interplanetary shock triggers large-amplitude ultralow-frequency (ULF) waves (|δB| ≥ 15 nT) in the Pc4–Pc5 wave band (1.6–9 mHz) near the noon geosynchronous orbit (6.6 RE). The local and global effects of ULF waves on energetic particles are observed by five Los Alamos National Laboratory satellites at different magnetic local times. The large-amplitude ULF waves cause the synchronous oscillations of energetic electrons and protons (≥75 keV) at the noon geosynchronous orbit. When the energetic particles have a negative phase space density radial gradient, they undergo rapid outward radial diffusion and loss in themore » wave activity region. In the particle drift paths without strong ULF waves, only the rapidly drifting energetic electrons (≥225 keV) display energy-dispersive oscillations and flux decays, whereas the slowly drifting electrons (<225 keV) and protons (75–400 keV) have no ULF oscillation and loss feature. When the dayside magnetopause is compressed to the geosynchronous orbit, most of energetic electrons and protons are rapidly lost because of open drift trajectories. Furthermore, the global and multicomposition particle measurements demonstrate that the effect of ULF waves on nonlocal particle flux depends on the particle energy and species, whereas magnetopause shadowing effect is independent of the energetic particle species. For the rapidly drifting outer radiation belt particles (≥225 keV), nonlocal particle loss/acceleration processes could also change their fluxes in the entire drift trajectory in the absence of “ Dst effect” and substorm injection.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720053663&hterms=shock+elastic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dshock%2Belastic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720053663&hterms=shock+elastic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dshock%2Belastic">Longitudinal waves in a perpendicular collisionless plasma shock. IV - Gradient B.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gary, S. P. 1972-01-01 The consideration of elastic waves in a Vlasov plasma of unmagnetized ions and magnetized electrons undergoing E x B electron drift and gradient B drift, pursued in the earlier three parts, is brought to conclusion in this last part of the longitudinal wave study in a collisionless plasma shock. Detailed calculations of the effects of the beta sub e dimensionless parameter on the E x B electron drift instability are presented. It is shown that the range of propagation of the elastic waves about the perpendicular remains quite narrow, and that, for oblique propagation, the already narrow angular range of unstable waves is decreased by increases in the value of the beta sub e dimensionless parameter. Also, increases in wave number generally reduce the growth rate and the angular range of propagation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ChPhL..20..688P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ChPhL..20..688P">Electron Injection by E-Field Drift and its Application in Starting-up Tokamaks at Low Loop Voltage</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pan, Yuan; Yan, Xiao-Lin; Liu, Bao-Hua 2003-05-01 We propose an innovative method of electron injection by E-field drift into a plasma device and discuss its application in starting-up tokamak plasmas at low loop voltage. The experimental results obtained from HT-6M Tokamak are also presented. The breakdown loop voltage is obviously reduced and the discharge performance is improved by using the electron injection method. It could be applied to some other types of plasma device. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23a3112Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23a3112Z">Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhu, X. P.; Zhang, Z. C.; Pushkarev, A. I.; Lei, M. K. 2016-01-01 High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1260161-liter-test-stand-gas-purification-liquid-argon-research','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1260161-liter-test-stand-gas-purification-liquid-argon-research">A 20-liter test stand with gas purification for liquid argon research</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Li, Y.; Thorn, C.; Tang, W.; ... 2016-06-06 Here, we describe the design of a 20-liter test stand constructed to study fundamental properties of liquid argon (LAr). Moreover, this system utilizes a simple, cost-effective gas argon (GAr) purification to achieve high purity, which is necessary to study electron transport properties in LAr. An electron drift stack with up to 25 cm length is constructed to study electron drift, diffusion, and attachment at various electric fields. Finally, a gold photocathode and a pulsed laser are used as a bright electron source. The operational performance of this system is reported. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1260161','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1260161">A 20-liter test stand with gas purification for liquid argon research</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Li, Y.; Thorn, C.; Tang, W. Here, we describe the design of a 20-liter test stand constructed to study fundamental properties of liquid argon (LAr). Moreover, this system utilizes a simple, cost-effective gas argon (GAr) purification to achieve high purity, which is necessary to study electron transport properties in LAr. An electron drift stack with up to 25 cm length is constructed to study electron drift, diffusion, and attachment at various electric fields. Finally, a gold photocathode and a pulsed laser are used as a bright electron source. The operational performance of this system is reported. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25370658','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25370658">Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca 2014-11-01 A close proximity hybrid x-ray/magnetic resonance (XMR) imaging system offers several critical advantages over current XMR system installations that have large separation distances (∼5 m) between the imaging fields of view. The two imaging systems can be placed in close proximity to each other if an x-ray tube can be designed to be immune to the magnetic fringe fields outside of the MR bore. One of the major obstacles to robust x-ray tube design is correcting for the effects of the MR fringe field on the x-ray tube focal spot. Any fringe field component orthogonal to the x-ray tube electric field leads to electron drift altering the path of the electron trajectories. The method proposed in this study to correct for the electron drift utilizes an external electric field in the direction of the drift. The electric field is created using two electrodes that are positioned adjacent to the cathode. These electrodes are biased with positive and negative potential differences relative to the cathode. The design of the focusing cup assembly is constrained primarily by the strength of the MR fringe field and high voltage standoff distances between the anode, cathode, and the bias electrodes. From these constraints, a focusing cup design suitable for the close proximity XMR system geometry is derived, and a finite element model of this focusing cup geometry is simulated to demonstrate efficacy. A Monte Carlo simulation is performed to determine any effects of the modified focusing cup design on the output x-ray energy spectrum. An orthogonal fringe field magnitude of 65 mT can be compensated for using bias voltages of +15 and -20 kV. These bias voltages are not sufficient to completely correct for larger orthogonal field magnitudes. Using active shielding coils in combination with the bias electrodes provides complete correction at an orthogonal field magnitude of 88.1 mT. Introducing small fields (<10 mT) parallel to the x-ray tube electric field in addition to the orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray tube by 30° toward the MR bore increases the parallel magnetic field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output flux is reduced by 7.5%. The maximum orthogonal magnetic field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray tube insert. The electrostatic approach also suffers from limitations when there are strong magnetic fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel magnetic field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4209011','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4209011">Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca 2014-01-01 Purpose: A close proximity hybrid x-ray/magnetic resonance (XMR) imaging system offers several critical advantages over current XMR system installations that have large separation distances (∼5 m) between the imaging fields of view. The two imaging systems can be placed in close proximity to each other if an x-ray tube can be designed to be immune to the magnetic fringe fields outside of the MR bore. One of the major obstacles to robust x-ray tube design is correcting for the effects of the MR fringe field on the x-ray tube focal spot. Any fringe field component orthogonal to the x-ray tube electric field leads to electron drift altering the path of the electron trajectories. Methods: The method proposed in this study to correct for the electron drift utilizes an external electric field in the direction of the drift. The electric field is created using two electrodes that are positioned adjacent to the cathode. These electrodes are biased with positive and negative potential differences relative to the cathode. The design of the focusing cup assembly is constrained primarily by the strength of the MR fringe field and high voltage standoff distances between the anode, cathode, and the bias electrodes. From these constraints, a focusing cup design suitable for the close proximity XMR system geometry is derived, and a finite element model of this focusing cup geometry is simulated to demonstrate efficacy. A Monte Carlo simulation is performed to determine any effects of the modified focusing cup design on the output x-ray energy spectrum. Results: An orthogonal fringe field magnitude of 65 mT can be compensated for using bias voltages of +15 and −20 kV. These bias voltages are not sufficient to completely correct for larger orthogonal field magnitudes. Using active shielding coils in combination with the bias electrodes provides complete correction at an orthogonal field magnitude of 88.1 mT. Introducing small fields (<10 mT) parallel to the x-ray tube electric field in addition to the orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray tube by 30° toward the MR bore increases the parallel magnetic field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output flux is reduced by 7.5%. Conclusions: The maximum orthogonal magnetic field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray tube insert. The electrostatic approach also suffers from limitations when there are strong magnetic fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel magnetic field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes. PMID:25370658 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSM13C..03T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSM13C..03T">Quantification of the Precipitation Loss of Radiation Belt Electrons Observed by SAMPEX (Invited)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, W.; Li, X.; Selesnick, R. S.; Looper, M. D. 2010-12-01 Based on SAMPEX/PET observations, the fluxes and the spatial and temporal variations of electron loss to the atmosphere in the Earth’s radiation belt were quantified using a drift-diffusion model that includes the effects of azimuthal drift and pitch angle diffusion. The measured electrons by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), or precipitating (in the bounce loss cone), and the model simulates the low-altitude electron distribution from SAMPEX. After fitting the model results to the data, the magnitudes and variations of the electron loss rate can be estimated based on the optimum model parameter values. In this presentation we give an overview of our method and published results, followed by some recent improvements we made on the model, including updating the quantified electron lifetimes more frequently (e.g., every two hours instead of half a day) to achieve smoother variations, estimating the adiabatic effects at SAMPEX’s orbit and their influence on our model results, and calculating the error bar associated with each quantified electron lifetime. This method combining a model with low-altitude observations provides direct quantification of the electron loss rate, as required for any accurate modeling of the radiation belt electron dynamics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JInst..12P1020C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JInst..12P1020C">Cathode signal in a TPC directional detector: implementation and validation measuring the drift velocity</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Couturier, C.; Riffard, Q.; Sauzet, N.; Guillaudin, O.; Naraghi, F.; Santos, D. 2017-11-01 Low-pressure gaseous TPCs are well suited detectors to correlate the directions of nuclear recoils to the galactic Dark Matter (DM) halo. Indeed, in addition to providing a measure of the energy deposition due to the elastic scattering of a DM particle on a nucleus in the target gas, they allow for the reconstruction of the track of the recoiling nucleus. In order to exclude the background events originating from radioactive decays on the surfaces of the detector materials within the drift volume, efforts are ongoing to precisely localize the track nuclear recoil in the drift volume along the axis perpendicular to the cathode plane. We report here the implementation of the measure of the signal induced on the cathode by the motion of the primary electrons toward the anode in a MIMAC chamber. As a validation, we performed an independent measurement of the drift velocity of the electrons in the considered gas mixture, correlating in time the cathode signal with the measure of the arrival times of the electrons on the anode. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987NIMPA.255..486F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987NIMPA.255..486F">Trigger drift chamber for the upgraded mark II detector at PEP</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ford, W. T.; Smith, J. G.; Wagner, S. R.; Weber, P.; White, S. L.; Alvarez, M.; Calviño, F.; Fernandez, E. 1987-04-01 A small cylindrical track detector was built as an array of single-wire drift cells with aluminized mylar cathode tubes. Point measurement resolution of ˜ 90 μm was achieved with a drift gas of 50% argon-50% ethane at atmospheric pressure. The chamber construction, electronics, and calibration are discussed. Performance results from PEP colliding-beam data are presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22047237-pumping-eccentricity-exoplanets-tidal-effect','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22047237-pumping-eccentricity-exoplanets-tidal-effect">PUMPING THE ECCENTRICITY OF EXOPLANETS BY TIDAL EFFECT</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Correia, Alexandre C. M.; Boue, Gwenaeel; Laskar, Jacques, E-mail: correia@ua.pt 2012-01-10 Planets close to their host stars are believed to undergo significant tidal interactions, leading to a progressive damping of the orbital eccentricity. Here we show that when the orbit of the planet is excited by an outer companion, tidal effects combined with gravitational interactions may give rise to a secular increasing drift on the eccentricity. As long as this secular drift counterbalances the damping effect, the eccentricity can increase to high values. This mechanism may explain why some of the moderate close-in exoplanets are observed with substantial eccentricity values. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DPPCP9105I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DPPCP9105I">Characteristics of Muti-pulsing CHI driven ST plasmas on HIST</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ishihara, M.; Hanao, T.; Ito, K.; Matsumoto, K.; Higashi, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M. 2011-10-01 The flux amplification and sustainment of the ST configurations by operating in Multi-pulsing Coaxial Helicity Injection (M-CHI) method have been demonstrated on HIST. The multi-pulsing experiment was demonstrated in the SSPX spheromak device at LLNL. In the double pulsing discharges, we have observed that the plasma current has been sustained much longer against the resistive decay as compared to the single CHI. We have measured the radial profiles of the flow velocities by using Ion Doppler Spectrometer and Mach probes. The result shows that poloidal shear flow exists between the open flux column and the most outer closed flux surface. The poloidal velocity shear at the interface may be caused by the ion diamagnetic drift, because of a steep density gradient there. The radial electric field is determined by the flow velocities and the ion pressure gradient through the radial momentum balance equation. We have investigated the contribution of ExB or the ion pressure gradient on the poloidal velocity shear by comparing the impurity ion flow obtained from the IDS with the bulk ion flow from the Mach probe. It should be noted that the diamagnetic drift velocity of the impurity is much smaller than ExB drift velocity. We will discuss characteristics of M-CHI-driven ST plasmas by varying TF coil current and the line averaged electron density. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NIMPA.735..193S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NIMPA.735..193S">Front-end electronics of the Belle II drift chamber</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shimazaki, Shoichi; Taniguchi, Takashi; Uchida, Tomohisa; Ikeno, Masahiro; Taniguchi, Nanae; Tanaka, Manobu M. 2014-01-01 This paper describes the performance of the Belle II central drift chamber (CDC) front-end electronics. The front-end electronics consists of a current sensitive preamplifier, a 1/t cancellation circuit, baseline restorers, a comparator for timing measurement and an analog buffer for the dE/dx measurement on a CDC readout card. The CDC readout card is located on the endplate of the CDC. Mass production will be completed after the performance of the chip is verified. The electrical performance and results of a neutron/gamma-ray irradiation test are reported here. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRA..115.7210T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRA..115.7210T">Quantification of the precipitation loss of radiation belt electrons observed by SAMPEX</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, Weichao; Selesnick, Richard; Li, Xinlin; Looper, Mark 2010-07-01 Based on SAMPEX/PET observations, the rates and the spatial and temporal variations of electron loss to the atmosphere in the Earth's radiation belt were quantified using a drift diffusion model that includes the effects of azimuthal drift and pitch angle diffusion. The measured electrons by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), and precipitating (in the bounce loss cone). The drift diffusion model simulates the low-altitude electron distribution from SAMPEX. After fitting the model results to the data, the magnitudes and variations of the electron lifetime can be quantitatively determined based on the optimum model parameter values. Three magnetic storms of different magnitudes were selected to estimate the various loss rates of ˜0.5-3 MeV electrons during different phases of the storms and at L shells ranging from L = 3.5 to L = 6.5 (L represents the radial distance in the equatorial plane under a dipole field approximation). The storms represent a small storm, a moderate storm from the current solar minimum, and an intense storm right after the previous solar maximum. Model results for the three individual events showed that fast precipitation losses of relativistic electrons, as short as hours, persistently occurred in the storm main phases and with more efficient loss at higher energies over wide range of L regions and over all the SAMPEX-covered local times. In addition to this newly discovered common feature of the main phase electron loss for all the storm events and at all L locations, some other properties of the electron loss rates, such as the local time and energy dependence that vary with time or locations, were also estimated and discussed. This method combining model with the low-altitude observations provides direct quantification of the electron loss rate, a prerequisite for any comprehensive modeling of the radiation belt electron dynamics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSM23A1594T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSM23A1594T">Quantification of the Precipitation Loss of Radiation Belt Electrons Observed by SAMPEX</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, W.; Selesnick, R. S.; Li, X.; Looper, M. D. 2009-12-01 Based on SAMPEX/PET observations, the rates and the spatial and temporal variations of electron loss to the atmosphere in the Earth’s radiation belt were quantified using a Drift-Diffusion model that includes the effects of azimuthal drifts and pitch angle diffusion. The measured electrons detected by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), and precipitating (in the bounce loss cone). The Drift-Diffusion model simulates the low-altitude electron distribution from SAMPEX. After fitting the model results to the data, the magnitudes and variations of the electron lifetime can be quantitatively determined based on the optimum model parameter values. Three magnetic storms of different types of magnitude were selected to estimate the various loss rates of ~0.5 to 3 MeV electrons during different phases of the storm and at L shells ranging from L=3.5 to L=6.5 (L represents the radial distance in the equatorial plane under a dipole field approximation). They are a small storm and a moderate storm in the current solar minimum and an intense storm right after the previous solar maximum. Model results for the three individual events showed that fast precipitation losses of energetic radiation belt electrons, as short as hours, persistently occurred in the storm main phases and with more efficient loss at higher energies, over wide range of L regions and over all the SAMPEX covered local times. In addition to this newly discovered common feature of the main phase electron lifetimes for all the storm events and at all L locations, some other properties of the electron loss rates that vary with time or locations, were also estimated and discussed. This method combining model with the low-altitude observations provides direct quantification of the electron loss rate, a prerequisite for any comprehensive modeling of the radiation belt electron dynamics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24e3519T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24e3519T">Hall thruster microturbulence under conditions of modified electron wall emission</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tsikata, S.; Héron, A.; Honoré, C. 2017-05-01 In recent numerical, theoretical, and experimental papers, the short-scale electron cyclotron drift instability (ECDI) has been studied as a possible contributor to the anomalous electron current observed in Hall thrusters. In this work, features of the instability, in the presence of a zero-electron emission material at the thruster exit plane, are analyzed using coherent Thomson scattering. Limiting the electron emission at the exit plane alters the localization of the accelerating electric field and the expected drift velocity profile, which in turn modifies the amplitude and localization of the ECDI. The resulting changes to the standard thruster operation are expected to favor an increased contribution by the ECDI to electron current. Such an operation is associated with a degradation of thruster performance and stability. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active">8</li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active">9</li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JIMTW..32.1415K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JIMTW..32.1415K">Experimental Analysis of Pseudospark Sourced Electron Beam</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kumar, Niraj; Pal, U. N.; Verma, D. K.; Prajapati, J.; Kumar, M.; Meena, B. L.; Tyagi, M. S.; Srivastava, V. 2011-12-01 The pseudospark (PS) discharge has been shown to be a promising source of high brightness, high intensity electron beam pulses. The PS discharge sourced electron beam has potential applications in plasma filled microwave sources where normal material cathode cannot be used. Analysis of the electron beam profile has been done experimentally for different applied voltages. The investigation has been carried out at different axial and radial location inside the drift space in argon atmosphere. This paper represents experimentally found axial and radial variation of the beam current inside the drift tube of PS discharge based plasma cathode electron (PCE) gun. With the help of current density estimation the focusing and defocusing point of electron beam in axial direction can be analyzed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AnGeo..35...97K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AnGeo..35...97K">Scintillation measurements at Bahir Dar during the high solar activity phase of solar cycle 24</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kriegel, Martin; Jakowski, Norbert; Berdermann, Jens; Sato, Hiroatsu; Wassaie Mersha, Mogese 2017-01-01 Small-scale ionospheric disturbances may cause severe radio scintillations of signals transmitted from global navigation satellite systems (GNSSs). Consequently, small-scale plasma irregularities may heavily degrade the performance of current GNSSs such as GPS, GLONASS or Galileo. This paper presents analysis results obtained primarily from two high-rate GNSS receiver stations designed and operated by the German Aerospace Center (DLR) in cooperation with Bahir Dar University (BDU) at 11.6° N, 37.4° E. Both receivers collect raw data sampled at up to 50 Hz, from which characteristic scintillation parameters such as the S4 index are deduced. This paper gives a first overview of the measurement set-up and the observed scintillation events over Bahir Dar in 2015. Both stations are located close to one another and aligned in an east-west, direction which allows us to estimate the zonal drift velocity and spatial dimension of equatorial ionospheric plasma irregularities. Therefore, the lag times of moving electron density irregularities and scintillation patterns are derived by applying cross-correlation analysis to high-rate measurements of the slant total electron content (sTEC) along radio links between a GPS satellite and both receivers and to the associated signal power, respectively. Finally, the drift velocity is derived from the estimated lag time, taking into account the geometric constellation of both receiving antennas and the observed GPS satellites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JAP...122w4505H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAP...122w4505H">The ABC model of recombination reinterpreted: Impact on understanding carrier transport and efficiency droop in InGaN/GaN light emitting diodes</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hopkins, M. A.; Allsopp, D. W. E.; Kappers, M. J.; Oliver, R. A.; Humphreys, C. J. 2017-12-01 The efficiency of light emitting diodes (LEDs) remains a topic of great contemporary interest due to their potential to reduce the amount of energy consumed in lighting. The current consensus is that electrons and holes distribute themselves through the emissive region by a drift-diffusion process which results in a highly non-uniform distribution of the light emission and can reduce efficiency. In this paper, the measured variations in the external quantum efficiency of a range of InGaN/GaN LEDs with different numbers of quantum wells (QWs) are shown to compare closely with the predictions of a revised ABC model, in which it is assumed that the electrically injected electrons and holes are uniformly distributed through the multi-quantum well (MQW) region, or nearly so, and hence carrier recombination occurs equally in all the quantum wells. The implications of the reported results are that drift-diffusion plays a far lesser role in cross-well carrier transport than previously thought; that the dominant cause of efficiency droop is intrinsic to the quantum wells and that reductions in the density of non-radiative recombination centers in the MQW would enable the use of more QWs and thereby reduce Auger losses by spreading carriers more evenly across a wider emissive region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00759&hterms=Pink+eyes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPink%2Beyes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00759&hterms=Pink+eyes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPink%2Beyes">First look at rock & soil properties</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 1997-01-01 The earliest survey of spectral properties of the rocks and soils surrounding Pathfinder was acquired as a narrow strip covering the region just beyond the where the rover made its egress from the lander. The wavelength filters used, all in the binocular camera's right eye, cover mainly visible wavelengths. These data reveal at least five kinds of rocks and soil in the immediate vicinity of the lander. All of the spectra are ratioed to the mean spectrum of bright red drift to highlight the differences. Different occurrences of drift (pink spectra) are closely similar. Most of the rocks (black spectra) have a dark gray color, and are both darker and less red than the drift, suggesting less weathering. Typical soils (green spectra) are intermediate in properties to the rocks and drift. Both these data and subsequent higher resolution images show that the typical soil consists of a mixture of drift and small dark gray particles resembling the rock. However, two other kinds of materials are significantly different from the rocks and drift. Pinkish or whitish pebbles and crusts on some of the rocks (blue spectra) are brighter in blue light and darker in near-infrared light than is the drift, and they lack the spectral characteristics closely associated with iron minerals. Dark red soils in the lee of several rocks are about as red as the drift, but consistently darker. The curvature in the spectrum at visible wavelengths suggests either more ferric iron minerals than in the drift or a larger particle size.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA571944','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA571944">Model for Ultrafast Carrier Scattering in Semiconductors</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2012-11-14 energy transfer between semi-classical carrier drift-diffusion under an electric field and quantum kinetics of interband /intersubband transitions...from an electron during each phonon-emission event. The net rate of phonon emission is determined by the Boltzmann scattering equation which depends ...energy-drift term under a strong dc field was demonstrated to reduce the field- dependent drift velocity and mobility. The Doppler shift in the energy </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPBP8007K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPBP8007K">Effects of density gradient caused by multi-pulsing CHI on two-fluid flowing equilibria of spherical torus plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kanki, T.; Nagata, M. 2014-10-01 Two-fluid dynamo relaxation is examined to understand sustainment mechanism of spherical torus (ST) plasmas by multi-pulsing CHI (M-CHI) in the HIST device. The steeper density gradient between the central open flux column (OFC) and closed flux regions by applying the second CHI pulse is observed to cause not only the <emph type="bold-italic">E</emph> × <emph type="bold-italic">B</emph> drift but also the ion diamagnetic drift, leading the two-fluid dynamo. The purpose of this study is to investigate the effects of the steep change in the density gradient on the ST equilibria by using the two-fluid equilibrium calculations. The toroidal magnetic field becomes from a diamagnetic to a paramagnetic profile in the closed flux region while it remains a diamagnetic profile in the OFC region. The toroidal ion flow velocity is increased from negative to positive values in the closed flux region. Here, the negative ion flow velocity is the opposite direction to the toroidal current. The poloidal ion flow velocity between the OFC and closed flux regions is increased, because the ion diamagnetic drift velocity is changed in the same direction as the <emph type="bold-italic">E</emph> × <emph type="bold-italic">B</emph> drift velocity through the steeper ion pressure gradient. As a result, the strong shear flow and the paramagnetic toroidal field are generated in the closed flux region. Here, the ion flow velocity is the same direction as the poloidal current. The radial electric field shear between the OFC and closed flux regions is enhanced due to the strong dependence on the magnetic force through the interaction of toroidal ion flow velocity and axial magnetic field. The two-fluid effect is significant there due to the ion diamagnetic effect. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.2104W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.2104W">Electron heating in the exhaust of magnetic reconnection with negligible guide field</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wang, Shan; Chen, Li-Jen; Bessho, Naoki; Kistler, Lynn M.; Shuster, Jason R.; Guo, Ruilong 2016-03-01 Electron heating in the magnetic reconnection exhaust is investigated with particle-in-cell simulations, space observations, and theoretical analysis. Spatial variations of the electron temperature (Te) and associated velocity distribution functions (VDFs) are examined and understood in terms of particle energization and randomization processes that vary with exhaust locations. Inside the electron diffusion region (EDR), the electron temperature parallel to the magnetic field (Te∥) exhibits a local minimum and the perpendicular temperature (Te⊥) shows a maximum at the current sheet midplane. In the intermediate exhaust downstream from the EDR and far from the magnetic field pileup region, Te⊥/Te∥ is close to unity and Te is approximately uniform, but the VDFs are structured: close to the midplane, VDFs are quasi-isotropic, whereas farther away from the midplane, VDFs exhibit field-aligned beams directed toward the midplane. In the far exhaust, Te generally increases toward the midplane and the pileup region, and the corresponding VDFs show counter-streaming beams. A distinct population with low v∥ and high v⊥ is prominent in the VDFs around the midplane. Test particle results show that the magnetic curvature near the midplane produces pitch angle scattering to generate quasi-isotropic distributions in the intermediate exhaust. In the far exhaust, electrons with initial high v∥ (v⊥) are accelerated mainly through curvature (gradient-B) drift opposite to the electric field, without significant pitch angle scattering. The VDF structures predicted by simulations are observed in magnetotail reconnection measurements, indicating that the energization mechanisms captured in the reported simulations are applicable to magnetotail reconnection with negligible guide field. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24444498','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24444498">Revolving scanning transmission electron microscopy: correcting sample drift distortion without prior knowledge.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Sang, Xiahan; LeBeau, James M 2014-03-01 We report the development of revolving scanning transmission electron microscopy--RevSTEM--a technique that enables characterization and removal of sample drift distortion from atomic resolution images without the need for a priori crystal structure information. To measure and correct the distortion, we acquire an image series while rotating the scan coordinate system between successive frames. Through theory and experiment, we show that the revolving image series captures the information necessary to analyze sample drift rate and direction. At atomic resolution, we quantify the image distortion using the projective standard deviation, a rapid, real-space method to directly measure lattice vector angles. By fitting these angles to a physical model, we show that the refined drift parameters provide the input needed to correct distortion across the series. We demonstrate that RevSTEM simultaneously removes the need for a priori structure information to correct distortion, leads to a dramatically improved signal-to-noise ratio, and enables picometer precision and accuracy regardless of drift rate. Copyright © 2013 Elsevier B.V. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA631964','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA631964">Snow Drift Management: Summit Station Greenland</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2016-05-01 that about 25% of the estimated snow that the wind transports to Summit each winter is deposited and forms drifts, mostly in close proxim- ity to...the structures. This analysis demonstrates that weather data ( wind speed and direction) and a transport analysis can aid in estimating the vol- ume of...23 Appendix A: Wind Roses </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPGP8065K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPGP8065K">Properties of two-fluid flowing equilibria observed in double-pulsing coaxial helicity injection on HIST</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kanki, T.; Nagata, M. 2013-10-01 Multi-pulsing coaxial helicity injection (M-CHI) method which aims to achieve both quasi-steady sustainment and good confinement has been proposed as a refluxing scenario of the CHI. To explore the usefulness of the M-CHI for spherical torus (ST) configurations, the double-pulsing operations have been carried out in the HIST, verifying the flux amplification and the formation of the closed flux surfaces after the second CHI pulse. The purpose of this study is to investigate the properties of the magnetic field and plasma flow structures during the sustainment by comparing the results of plasma flow, density, and magnetic fields measurements with those of two-fluid equilibrium calculations. The two-fluid flowing equilibrium model which is described by a pair of generalized Grad-Shafranov equations for ion and electron surface variables and Bernoulli equations for density is applied to reconstruct the ST configuration with poloidal flow shear observed in the HIST. Due to the negative steep density gradient in high field side, the toroidal field has a diamagnetic profile (volume average beta, < β > = 68 %) in the central open flux column region. The ion flow velocity with strong flow shear from the separatrix in the inboard side to the core region is the opposite direction to the electron flow velocity due to the diamagentic drift through the density gradient. The electric field is relatively small in the whole region, and thus the Lorentz force nearly balances with the two-fluid effect which is particularly significant in a region with the steep density gradient due to the ion and electron diamagnetic drifts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM24A..01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM24A..01H">Nonlinear Kinetic Instabilities in Plasma Wakes</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hutchinson, I. H.; Haakonsen, C. B. 2015-12-01 Relative motion of a plasma and an embedded perturbing solid objectproduces a plasma wake, which is kinetically unstable. For moons,asteroids, spacecraft, probes, and planets without a magnetosphere theresponse is dominantly electrostatic, although generally with abackground magnetic field. Using high-fidelity particle-in-cellsimulations, we have observed the development of kinetic instabilitiesand their non-linear consequences in representative wakes. We havealso explained the observations with semi-analytical non-lineartheory. The ion and electron distribution function shapes are stronglyperturbed in the wake region. The ions form two opposite beamsdirected inward along the guiding magnetic field, in part because ofthe attraction of the wake's electric potential well. The electrondistribution forms a notch or dimple (of reduced phase space density)localized in velocity to orbits that dwell near the wake axis (becauseof repulsion). Those orbits are de-energized by cross-field drift downthe potential-energy ridge. The resulting Langmuir instability spawnselectron holes. The holes that move faster than the ion beams areaccelerated out of the wake by its electrostatic field without growingsubstantially. Some holes, however, remain in the wake at essentiallyzero parallel velocity. They grow, as a result of the same mechanismthat formed the notch: cross-field drift from a lower to a higherdensity. When the density rises by a factor of order two or three,they grow large enough to perturb the ions, tap their free energy, anddisrupt the ion streams well before they would become ion-ionunstable. Crucially, these processes depend strongly on theion/electron mass ratio and require close to physical ratio (1836) insimulations, to reveal their characteristics. Electron holes arisingfrom these processes may be widely present and observable in spaceplasma wakes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29906189','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29906189">Electron Bulk Acceleration and Thermalization at Earth's Quasiperpendicular Bow Shock.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Chen, L-J; Wang, S; Wilson, L B; Schwartz, S; Bessho, N; Moore, T; Gershman, D; Giles, B; Malaspina, D; Wilder, F D; Ergun, R E; Hesse, M; Lai, H; Russell, C; Strangeway, R; Torbert, R B; F-Vinas, A; Burch, J; Lee, S; Pollock, C; Dorelli, J; Paterson, W; Ahmadi, N; Goodrich, K; Lavraud, B; Le Contel, O; Khotyaintsev, Yu V; Lindqvist, P-A; Boardsen, S; Wei, H; Le, A; Avanov, L 2018-06-01 Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvL.120v5101C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvL.120v5101C">Electron Bulk Acceleration and Thermalization at Earth's Quasiperpendicular Bow Shock</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chen, L.-J.; Wang, S.; Wilson, L. B.; Schwartz, S.; Bessho, N.; Moore, T.; Gershman, D.; Giles, B.; Malaspina, D.; Wilder, F. D.; Ergun, R. E.; Hesse, M.; Lai, H.; Russell, C.; Strangeway, R.; Torbert, R. B.; F.-Vinas, A.; Burch, J.; Lee, S.; Pollock, C.; Dorelli, J.; Paterson, W.; Ahmadi, N.; Goodrich, K.; Lavraud, B.; Le Contel, O.; Khotyaintsev, Yu. V.; Lindqvist, P.-A.; Boardsen, S.; Wei, H.; Le, A.; Avanov, L. 2018-06-01 Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvL.122v5101C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvL.122v5101C">Electron bulk acceleration and thermalization at Earth's quasi-perpendicular bow shock</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chen, L.-J.; Wang, S.; Wilson, L. B., III; Schwartz, S. J.; Bessho, N.; Moore, T. E.; Gershman, D. J.; Giles, B. L.; Malaspina, D. M.; Wilder, F. D.; Ergun, R. E.; Hesse, M.; Lai, H.; Russell, C. T.; Strangeway, R. J.; Torbert, R. B.; Vinas, A. F.-; Burch, J. L.; Lee, S.; Pollock, C.; Dorelli, J.; Paterson, W. R.; Ahmadi, N.; Goodrich, K. A.; Lavraud, B.; Le Contel, O.; Khotyaintsev, Yu. V.; Lindqvist, P.-A.; Boardsen, S.; Wei, H.; Le, A.; Avanov, L. A. 2018-05-01 Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1289726','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1289726">The Liquid Argon Purity Demonstrator</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Adamowski, M.; Carls, B.; Dvorak, E. 2014-07-01 The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to themore » cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910008415','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910008415">Interaction of a neutral cloud moving through a magnetized plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Goertz, C. K.; Lu, G. 1990-01-01 Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23440636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23440636">Acquisition parameters optimization of a transmission electron forward scatter diffraction system in a cold-field emission scanning electron microscope for nanomaterials characterization.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Brodusch, Nicolas; Demers, Hendrix; Trudeau, Michel; Gauvin, Raynald 2013-01-01 Transmission electron forward scatter diffraction (t-EFSD) is a new technique providing crystallographic information with high resolution on thin specimens by using a conventional electron backscatter diffraction (EBSD) system in a scanning electron microscope. In this study, the impact of tilt angle, working distance, and detector distance on the Kikuchi pattern quality were investigated in a cold-field emission scanning electron microscope (CFE-SEM). We demonstrated that t-EFSD is applicable for tilt angles ranging from -20° to -40°. Working distance (WD) should be optimized for each material by choosing the WD for which the EBSD camera screen illumination is the highest, as the number of detected electrons on the screen is directly dependent on the scattering angle. To take advantage of the best performances of the CFE-SEM, the EBSD camera should be close to the sample and oriented towards the bottom to increase forward scattered electron collection efficiency. However, specimen chamber cluttering and beam/mechanical drift are important limitations in the CFE-SEM used in this work. Finally, the importance of t-EFSD in materials science characterization was illustrated through three examples of phase identification and orientation mapping. © Wiley Periodicals, Inc. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.4192Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.4192Z">Equatorial Ionospheric Disturbance Field-Aligned Plasma Drifts Observed by C/NOFS</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhang, Ruilong; Liu, Libo; Balan, N.; Le, Huijun; Chen, Yiding; Zhao, Biqiang 2018-05-01 Using C/NOFS satellite observations, this paper studies the disturbance field-aligned plasma drifts in the equatorial topside ionosphere during eight geomagnetic storms in 2011-2015. During all six storms occurred in the solstices, the disturbance field-aligned plasma drift is from winter to summer hemisphere especially in the morning-midnight local time sector and the disturbance is stronger in June solstice. The two storms occurred at equinoxes have very little effect on the field-aligned plasma drift. Using the plasma temperature data from DMSP satellites and Global Positioning System-total electron content, it is suggested that the plasma density gradient seems likely to cause the disturbance winter-to-summer plasma drift while the role of plasma temperature gradient is opposite to the observed plasma drift. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9839E..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9839E..08S">Amplifying the helicopter drift in a conformal HMD</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Schmerwitz, Sven; Knabl, Patrizia M.; Lueken, Thomas; Doehler, Hans-Ullrich 2016-05-01 Helicopter operations require a well-controlled and minimal lateral drift shortly before ground contact. Any lateral speed exceeding this small threshold can cause a dangerous momentum around the roll axis, which may cause a total roll over of the helicopter. As long as pilots can observe visual cues from the ground, they are able to easily control the helicopter drift. But whenever natural vision is reduced or even obscured, e.g. due to night, fog, or dust, this controllability diminishes. Therefore helicopter operators could benefit from some type of "drift indication" that mitigates the influence of a degraded visual environment. Generally humans derive ego motion by the perceived environmental object flow. The visual cues perceived are located close to the helicopter, therefore even small movements can be recognized. This fact was used to investigate a modified drift indication. To enhance the perception of ego motion in a conformal HMD symbol set the measured movement was used to generate a pattern motion in the forward field of view close or on the landing pad. The paper will discuss the method of amplified ego motion drift indication. Aspects concerning impact factors like visualization type, location, gain and more will be addressed. Further conclusions from previous studies, a high fidelity experiment and a part task experiment, will be provided. A part task study will be presented that compared different amplified drift indications against a predictor. 24 participants, 15 holding a fixed wing license and 4 helicopter pilots, had to perform a dual task on a virtual reality headset. A simplified control model was used to steer a "helicopter" down to a landing pad while acknowledging randomly placed characters. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995ApJ...455..347A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995ApJ...455..347A">Solar Electron Beams Detected in Hard X-Rays and Radio Waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Aschwanden, Markus J.; Benz, Arnold O.; Dennis, Brian R.; Schwartz, Richard A. 1995-12-01 We present a statistical survey of electron beam signatures that are detected simultaneously at hard X-ray (HXR) and radio wavelengths during solar flares. For the identification of a simultaneous event we require a type III (normal-drifting or reverse-slope-drifting) radio burst that coincides (within ± 1 s) with a significant (≥ 3 σ HXR pulse of similar duration (≥ 1 s). Our survey covers all HXRBS/SMM and BATSE/CGRO flares that were simultaneously observed with the 0.1-1 GHz spectrometer Ikarus or the 0.1-3 GHz spectrometer Phoenix of ETH Zurich during 1980-1993. The major results and conclusions are as follows: 1. We identified 233 HXR pulses (out of 882) to be correlated with type III-like radio bursts: 77% with normal-drifting type III bursts, 34% with reverse-slope (RS)-drifting bursts, and 13% with oppositely drifting (III + RS) burst pairs. The majority of these cases provide evidence for acceleration of bidirectional electron beams. 2. The detailed correlation with type III-like radio bursts suggests that most of the subsecond fluctuations detectable in ≥ 25 keV HXR emission are related to discrete electron injections. This is also supported by the proportionality of the HXR pulse duration with the radio burst duration. The distribution of HXR pulse durations WX is found to have an exponential distribution, i.e., N(WX) ∝ exp (-WX/0.25 s) in the measured range of WX ≍ 0.5-1.5 s. 3. From oppositely drifting radio burst pairs we infer electron densities of ne = 109-1010 cm-3 at the acceleration site. From the absence of a frequency gap between the simultaneous start frequencies of upward and downward drifting radio bursts, we infer an upper limit of L ≤ 2000 km for the extent of the acceleration site and an acceleration time of Δt ≤ 3 ms for the (≥ 5 keV) radio-emitting electrons (in the case of parallel electric fields). 4. The relative timing between HXR pulses and radio bursts is best at the start frequency (of earliest radio detection), with a coincidence of ≲0.1 s in the statistical average, while the radio bursts are delayed at all other frequencies (in the statistical average). The timing is consistent with the scenario of electron injection at a mean coronal height of h ≍ 104 km. The radio-emitting electrons are found to have lower energies (≳ 5 keV) than the ≥ 25 keV HXR-emitting electrons. 5. The modulated HXR flux that correlates with electron beam signatures in radio amounts to 2%-6% of the total HXR count rate (for BATSE flares). The associated kinetic energy in electrons is estimated to be E = 4 × 1022-1027 ergs per beam, or Ne = 4 × 1028-1033 electrons per beam, considering the spread from the smallest to the largest flare detected by HXRBS. 6. The average drift rate of propagating electron beams is found here to be [dv/dt] = 0.10ν1.4 MHz km s-1 in the frequency range of ν = 200-3000 MHz, which is lower than expected from the Alvarez & Haddock relation for frequencies ≤ 550 MHz. 7. The frequency distributions of HXR fluxes (Fx) and radio type III burst fluxes (FR), which both can be characterized by a power law, are found to have a significantly different slope, i.e., N(Fx) ∝ Fx-1.87 versus N(FR) ∝ FR-1.28. The difference in the slope is attributed to the fundamental difference between incoherent and coherent emission processes. In summary, these findings suggest a flare scenario in which bidirectional streams of electrons are accelerated during solar flares at heights of 10 km above the photosphere in rather compact regions (L ≲ 2000 km). The acceleration site is likely to be located near the top of flare loops (defined by HXR double footpoints) or in the cusp above, where electrons have also access to open field lines or larger arches. The observed bidirectionality of electron beams favors acceleration mechanisms with oppositely directed electric fields or stochastic acceleration in an X-type reconnection geometry. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active">9</li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active">10</li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770020316&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770020316&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam">Current-limited electron beam injection</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Stenzel, R. L. 1977-01-01 The injection of an electron beam into a weakly collisional, magnetized background plasma was investigated experimentally. The injected beam was energetic and cold, the background plasma was initially isothermal. Beam and plasma dimensions were so large that the system was considered unbounded. The temporal and spatial evolution of the beam-plasma system was dominated by collective effects. High-frequency electrostatic instabilities rapidly thermalized the beam and heated the background electrons. The injected beam current was balanced by a return current consisting of background electrons drifting toward the beam source. The drift between electrons and ions gave rise to an ion acoustic instability which developed into strong three-dimensional turbulence. It was shown that the injected beam current was limited by the return current which is approximately given by the electron saturation current. Non-Maxwellian electron distribution functions were observed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22490001-electromagnetic-drift-waves-dispersion-arbitrarily-collisional-plasmas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22490001-electromagnetic-drift-waves-dispersion-arbitrarily-collisional-plasmas">Electromagnetic drift waves dispersion for arbitrarily collisional plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Lee, Wonjae, E-mail: wol023@ucsd.edu; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu; Angus, J. R. 2015-07-15 The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionlessmore » and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22025579-self-organization-self-limitation-high-power-impulse-magnetron-sputtering','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22025579-self-organization-self-limitation-high-power-impulse-magnetron-sputtering">Self-organization and self-limitation in high power impulse magnetron sputtering</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Anders, Andre The plasma over the racetrack in high power impulse magnetron sputtering develops in traveling ionization zones. Power densities can locally reach 10{sup 9} W/m{sup 2}, which is much higher than usually reported. Ionization zones move because ions are 'evacuated' by the electric field, exposing neutrals to magnetically confined, drifting electrons. Drifting secondary electrons amplify ionization of the same ionization zone where the primary ions came from, while sputtered and outgassing atoms are supplied to the following zone(s). Strong density gradients parallel to the target disrupt electron confinement: a negative feedback mechanism that stabilizes ionization runaway. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864689','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864689">Klystron having electrostatic quadrupole focusing arrangement</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Maschke, Alfred W. 1983-08-30 A klystron includes a source for emitting at least one electron beam, and an accelerator for accelarating the beam in a given direction through a number of drift tube sections successively aligned relative to one another in the direction of the beam. A number of electrostatic quadrupole arrays are successively aligned relative to one another along at least one of the drift tube sections in the beam direction for focusing the electron beam. Each of the electrostatic quadrupole arrays forms a different quadrupole for each electron beam. Two or more electron beams can be maintained in parallel relationship by the quadrupole arrays, thereby enabling space charge limitations encountered with conventional single beam klystrons to be overcome. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/7245413','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/7245413">Klystron having electrostatic quadrupole focusing arrangement</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Maschke, A.W. 1983-08-30 A klystron includes a source for emitting at least one electron beam, and an accelerator for accelerating the beam in a given direction through a number of drift tube sections successively aligned relative to one another in the direction of the beam. A number of electrostatic quadrupole arrays are successively aligned relative to one another along at least one of the drift tube sections in the beam direction for focusing the electron beam. Each of the electrostatic quadrupole arrays forms a different quadrupole for each electron beam. Two or more electron beams can be maintained in parallel relationship by the quadrupole arrays, thereby enabling space charge limitations encountered with conventional single beam klystrons to be overcome. 4 figs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSH33C2247T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSH33C2247T">From Low Altitude to High Altitude: Assimilating SAMPEX Data in Global Radiation Belt Models by Quantifying Precipitation and Loss</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, W.; Reeves, G. D.; Cunningham, G.; Selesnick, R. S.; Li, X.; Looper, M. D. 2012-12-01 Since its launch in 1992, SAMPEX has been continuously providing measurements of radiation belt electrons at low altitude, which are not only ideal for the direct quantification of the electron precipitation loss in the radiation belt, but also provide data coverage in a critical region for global radiation belt data assimilation models. However, quantitatively combining high-altitude and low-earth-orbit (LEO) measurements on the same L-shell is challenging because LEO measurements typically contain a dynamic mixture of trapped and precipitating populations. Specifically, the electrons measured by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), and precipitating (in the bounce loss cone). To simulate the low-altitude electron distribution observed by SAMPEX/PET, a drift-diffusion model has been developed that includes the effects of azimuthal drift and pitch angle diffusion. The simulation provides direct quantification of the rates and variations of electron loss to the atmosphere, a direct input to our Dynamic Radiation Environment Assimilation Model (DREAM) as the electron loss lifetimes. The current DREAM uses data assimilation to combine a 1D radial diffusion model with observational data of radiation belt electrons. In order to implement the mixed electron measurements from SAMPEX into DREAM, we need to map the SAMPEX data from low altitude to high altitudes. To perform the mapping, we will first examine the well-known 'global coherence' of radiation belt electrons by comparing SAMPEX electron fluxes with the energetic electron data from LANL GEO and GPS spacecraft. If the correlation is good, we can directly map the SAMPEX fluxes to high altitudes based on the global coherence; if not, we will use the derived pitch angle distribution from the drift-diffusion model to map up the field and test the mapping by comparing to the high-altitude flux measurements. Then the globally mapped electron fluxes can be assimilated into DREAM. This new implementation of SAMPEX data will greatly augment the data coverage of DREAM and contribute to the global specification of the radiation belt environment. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950012617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950012617">Cross-tail current, field-aligned current, and B(y)</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kaufmann, Richard L.; Lu, Chen; Larson, Douglas J. 1994-01-01 Orbits of individual charged particles were traced in a one-dimensional magnetic field model that included a uniform cross-tail component B(sub yo). The effects of B(sub yo) on the cross-tail current distribution j(sub y)(z), the average cross-tail drift velocity(nu(sub y)z), and the average pitch angle change(delta alpha) experienced during current sheet encounters were calculated. The addition of a B(sub yo) that exceeded several tenths of one nanotesla completely eliminated all resonance effects for odd-N orbits. An odd-N resonance involves ions that enter and exit the current sheet on the same side. Pitch angles of nearly all such ions changed substantially during a typical current sheet interaction, and there was no region of large cross-tail drift velocity in the presence of a modest B(sub yo). the addition of a very large B(sub yo) guide field in the direction that enhances the natural drift produces a large j(y) and small (Delta alpha) for ions with all energies. The addition of a modest B(sub yo) had less effect near even-N resonances. In this case, ions in a small energy range were found to undergo so little change in pitch angle that particles which originated in the ionosphere would pass through the current sheet and return to the conjugate ionosphere. Finally, the cross-tail drift of ions from regions dominated by stochastic orbits to regions dominated by either resonant or guiding center orbits was considered. The ion drift speed changed substantially during such transitions. The accompanying electrons obey the guiding center equations, so electron drift is more uniform. Any difference between gradients in the fluxes associated with electron and ion drifts requires the presence of a Birkeland current in order to maintain charge neutrality. This plasma sheet region therefore serves as a current generator. The analysis predicts that the resulting Birkeland current connects to the lowest altitude equatorial regions in which ions drift to or from a point at which stochastic orbits predominate. The proposed mechanism appears only in analyses that include non-guiding-center effects. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995PhDT........63Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995PhDT........63Y">Measurement of Effective Drift Velocities of Electrons and Holes in Shallow Multiple Quantum Well P-I Modulators</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yang, Ching-Mei 1995-01-01 P-i-n diodes containing multiple quantum wells (MQWs) in the i-region are the building blocks for photonic devices. When we apply electric field across these devices and illuminate it with light, photo-carriers are created in the i-region. These carriers escape from the wells and drift toward the electrodes; thus photo-voltage is created. The rise- and decay-times of photo-voltages are related to the transport of carriers. In this dissertation, we present theoretical and experimental studies on carrier transport mechanisms of three shallow MQW GaAs/Al _{x}Ga_{1-x}As p-i-n diodes (x = 0.02, 0.04, 0.08) at various bias voltages. We start with the description of the sample structures and their package. We then present the characteristics of these samples including their transmission spectra and responsivity. We will demonstrate that the over-all high quality of these samples, including a strong exciton resonant absorption, ~100% internal quantum efficiencies and completely depleted i-region at bias between +0.75 V to -5 V bias. In our theoretical studies, we first discuss the possible carrier sweep-out mechanisms and estimate the response times associated with these mechanisms. Based on our theoretical model, we conclude that only the drift times of carriers and enhanced diffusion times are important for shallow MQW p-i-n diodes: at high bias, the fast drift times of electrons and holes control the rise-times; at low bias, the slow drift times of holes and the enhanced diffusion times control the decay-times. We have performed picosecond time-resolved pump/probe electro-absorption measurements on these samples. We then obtained the drift times, effective drift velocities and effective mobilities of electrons and holes for these devices. We find that the carrier effective drift velocities (especially for holes) seemed insensitive to the Al concentration in the barriers (in the range of x = 2% to 8%), even though the x = 2% sample does show an overall faster response time. We think the slight difference of the rise- and decay-times of these devices may also be affected by random differences between the samples. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110009891','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110009891">Electric Field Observations of Plasma Convection, Shear, Alfven Waves, and other Phenomena Observed on Sounding Rockets in the Cusp and Boundary Layer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Pfaff, R. F. 2009-01-01 On December 14,2002, a NASA Black Brant X sounding rocket was launched equatorward from Ny Alesund, Spitzbergen (79 N) into the dayside cusp and subsequently cut across the open/closed field line boundary, reaching an apogee of771 km. The launch occurred during Bz negative conditions with strong By negative that was changing during the flight. SuperDarn (CUTLASS) radar and subsequent model patterns reveal a strong westward/poleward convection, indicating that the rocket traversed a rotational reversal in the afternoon merging cell. The payload returned DC electric and magnetic fields, plasma waves, energetic particle, suprathermal electron and ion, and thermal plasma data. We provide an overview of the main observations and focus on the DC electric field results, comparing the measured E x B plasma drifts in detail with the CUTLASS radar observations of plasma drifts gathered simultaneously in the same volume. The in situ DC electric fields reveal steady poleward flows within the cusp with strong shears at the interface of the closed/open field lines and within the boundary layer. We use the observations to discuss ionospheric signatures of the open/closed character of the cusp/low latitude boundary layer as a function of the IMF. The electric field and plasma density data also reveal the presence of very strong plasma irregularities with a large range of scales (10 m to 10 km) that exist within the open field line cusp region yet disappear when the payload was equatorward of the cusp on closed field lines. These intense low frequency wave observations are consistent with strong scintillations observed on the ground at Ny Alesund during the flight. We present detailed wave characteristics and discuss them in terms of Alfven waves and static irregularities that pervade the cusp region at all altitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004RScI...75.1554H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004RScI...75.1554H">Electronics for fast ion extraction from EBIS devices</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Höltermann, H.; Becker, R.; Kleinod, M.; Müller, I. 2004-05-01 Future synchrotrons for cancer therapy could profit from single turn injection in terms of size, costs, and ease of operation [O. Kester, R. Becker, and M. Kleinod, Rev. Sci. Instrum. 67 (1996)]. Short (˜1.5 μs) and intense (˜1.3 mA) pulses of highly charged light ions (C6+, N7+, O8+) are a requirement for these future therapy facilities which can be provided by an EBIS ion source. Such a medically dedicated EBIS has an electron beam of 400 mA at 5 keV and needs an electron current density of 100 A/cm2 for a repetition rate of 10 Hz. To obtain a 1.5 μs ion pulse it is necessary to switch the drift tube potentials up to 1.6 kV (for a ratio of beam to drift tube of 1/20) in some 100 ns. To avoid spreading out of the pulse due to the restoration of the full space charge depression at locations where ions have already been extracted, the potentials applied to the drift tubes are changed with time. They will be adjusted for each drift tube according to the transit time of the ion pulse. Furthermore, the drift tubes are fully interpenetrating each other with tapered fingers in order to locally distribute the action of the applied potentials. This provides a potential wall, which is following the extracted ion pulse and results in a compressed short ion pulse for single turn injection into a synchrotron. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1362...25D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1362...25D">Covariance Matrix Adaptation Evolutionary Strategy for Drift Correction of Electronic Nose Data</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Di Carlo, S.; Falasconi, M.; Sanchez, E.; Sberveglieri, G.; Scionti, A.; Squillero, G.; Tonda, A. 2011-09-01 Electronic Noses (ENs) might represent a simple, fast, high sample throughput and economic alternative to conventional analytical instruments [1]. However, gas sensors drift still limits the EN adoption in real industrial setups due to high recalibration effort and cost [2]. In fact, pattern recognition (PaRC) models built in the training phase become useless after a period of time, in some cases a few weeks. Although algorithms to mitigate the drift date back to the early 90 this is still a challenging issue for the chemical sensor community [3]. Among other approaches, adaptive drift correction methods adjust the PaRC model in parallel with data acquisition without need of periodic calibration. Self-Organizing Maps (SOMs) [4] and Adaptive Resonance Theory (ART) networks [5] have been already tested in the past with fair success. This paper presents and discusses an original methodology based on a Covariance Matrix Adaptation Evolution Strategy (CMA-ES) [6], suited for stochastic optimization of complex problems. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/21274244-coupled-nonlinear-drift-ion-acoustic-waves-dense-dissipative-electron-positron-ion-magnetoplasmas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21274244-coupled-nonlinear-drift-ion-acoustic-waves-dense-dissipative-electron-positron-ion-magnetoplasmas">Coupled nonlinear drift and ion acoustic waves in dense dissipative electron-positron-ion magnetoplasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Masood, W.; Siddiq, M.; Karim, S. 2009-11-15 Linear and nonlinear propagation characteristics of drift ion acoustic waves are investigated in an inhomogeneous electron-positron-ion (e-p-i) quantum magnetoplasma with neutrals in the background using the well known quantum hydrodynamic model. In this regard, Korteweg-de Vries-Burgers (KdVB) and Kadomtsev-Petviashvili-Burgers (KPB) equations are obtained. Furthermore, the solutions of KdVB and KPB equations are presented by using the tangent hyperbolic (tanh) method. The variation in the shock profile with the quantum Bohm potential, collision frequency, and the ratio of drift to shock velocity in the comoving frame, v{sub *}/u, is also investigated. It is found that increasing the positron concentration and collisionmore » frequency decreases the strength of the shock. It is also shown that when the localized structure propagates with velocity greater than the diamagnetic drift velocity (i.e., u>v{sub *}), the shock strength decreases. However, the shock strength is observed to increase when the localized structure propagates with velocity less than that of drift velocity (i.e., u<v{sub *}). The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ESASP.641E..56B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ESASP.641E..56B">T he Faint Drifting Decameter Radio Bursts From The Solar Corona</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Briand, C.; Zaslavsky, A.; Lecacheux, A.; Zarka, P.; Maksimovic, M.; Mangeney, A. 2007-01-01 The radio observations of solar corona at decameter wavelengths reveal the presence of numerous faint, frequency drifting structures. We analyse observations performed on July 13th , 2002 with the DSP wideband spectrometer instrument implemented at the UTR-2 radiote- lescope. The main characteristics of these structures are statistically studied. Three populations of bursts are iden- tifies. The largest one presents negative frequency drifts of about -0.89 MHz.s-1 and a lifetime extending up to 11 sec (median value 2.72 sec). A second one shows positive frequency drifts of about +0.95 MHz.s-1 and a life- time extending up to 3 sec. The last population consists in structures with very small frequency drifts of about -0.1 MHz.s-1 and a shorter lifetime (about 1 sec). Assuming that those emissions are the signature of elec- tron beams propagating through the solar corona, we deduce that they have a velocity of about 3-5 times the electron thermal velocity. A new mechanism is proposed to explain the formation of plasma waves with such low beam velocity: spatially localized, temporal fluctuations of the electron distribution function width (heating). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860053173&hterms=function+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfunction%2Bwave','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860053173&hterms=function+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfunction%2Bwave">Statistical properties and correlation functions for drift waves</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Horton, W. 1986-01-01 The dissipative one-field drift wave equation is solved using the pseudospectral method to generate steady-state fluctuations. The fluctuations are analyzed in terms of space-time correlation functions and modal probability distributions. Nearly Gaussian statistics and exponential decay of the two-time correlation functions occur in the presence of electron dissipation, while in the absence of electron dissipation long-lived vortical structures occur. Formulas from renormalized, Markovianized statistical turbulence theory are given in a local approximation to interpret the dissipative turbulence. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020024779&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020024779&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam">Thermal Electron Contributions to Current-Driven Instabilities: SCIFER Observations in the 1400-km Cleft Ion Fountain and Their Implications to Thermal Ion Energization</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Adrian, Mark L.; Pollock, C. J.; Moore, T. E.; Kintner, P. M.; Arnoldy, R. L.; Whitaker, Ann F. (Technical Monitor) 2001-01-01 SCIFER TECHS observations of the variations in the thermal electron distribution in the 1400-km altitude cleft are associated with periods of intense ion heating and field-aligned currents. Energization of the thermal ion plasma in the mid-altitude cleft occurs within density cavities accompanied by enhanced thermal electron temperatures, large field-aligned thermal electron plasma flows and broadband low-frequency electric fields. Variations in the thermal electron contribution to field-aligned current densities indicate small scale (approximately 100's m) filamentary structure embedded within the ion energization periods. TECHS observations of the field-aligned drift velocities and temperatures of the thermal electron distribution are presented to evaluate the critical velocity thresholds necessary for the generation of electrostatic ion cyclotron and ion acoustic instabilities. This analysis suggests that, during periods of thermal ion energization, sufficient drift exists in the thermal electron distribution to excite the electrostatic ion cyclotron instability. In addition, brief periods exist within the same interval where the drift of the thermal electron distribution is sufficient to marginally excite the ion acoustic instability. In addition, the presence an enhancement in Langmuir emission at the plasma frequency at the center of the ion energization region, accompanied by the emission's second-harmonic, and collocated with observations of high-frequency electric field solitary structures suggest the presence of electron beam driven decay of Langmuir waves to ion acoustic modes as an additional free energy source for ion energization. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1402595-electron-dropout-echoes-induced-interplanetary-shock-van-allen-probes-observations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1402595-electron-dropout-echoes-induced-interplanetary-shock-van-allen-probes-observations">Electron dropout echoes induced by interplanetary shock: Van Allen Probes observations</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Hao, Y. X.; Zong, Q. -G.; Zhou, X. -Z.; ... 2016-06-07 On 23 November 2012, a sudden dropout of the relativistic electron flux was observed after an interplanetary shock arrival. The dropout peaks at ~1 MeV and more than 80% of the electrons disappeared from the drift shell. Van Allen twin Probes observed a sharp electron flux dropout with clear energy dispersion signals. The repeating flux dropout and recovery signatures, or “dropout echoes”, constitute a new phenomenon referred to as a “drifting electron dropout” with a limited initial spatial range. The azimuthal range of the dropout is estimated to be on the duskside, from ~1300 to 0100 LT. We then concludemore » that the shock-induced electron dropout is not caused by the magnetopause shadowing. Furthermore, the dropout and consequent echoes suggest that the radial migration of relativistic electrons is induced by the strong dusk-dawn asymmetric interplanetary shock compression on the magnetosphere.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28314235','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28314235">Primary and secondary pesticide drift profiles from a peach orchard.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Zivan, Ohad; Bohbot-Raviv, Yardena; Dubowski, Yael 2017-06-01 Atmospheric drift is considered a major loss path of pesticide from target areas, but there is still a large gap of knowledge regarding this complex phenomenon. Pesticide drift may occur during application (Primary drift) and after it (Secondary drift). The present study focuses on primary and secondary drift from ground applications in peach orchard (tree height of 3 m), under Mediterranean climate. Detailed and prolonged vertical drift profiles at close proximity to orchard are presented, together with detailed measurements of key meteorological parameters. The effect of volatility on drift was also studied by simultaneously applying two pesticides that differ in their volatility. Drifting airborne pesticides were detected both during and after applications at sampling distances of 7 and 20 m away from orchard edge. Concentrations ranged between hundreds ng m -3 to a few μg m -3 and showed clear decrease with time and with upwind conditions. Almost no decline in concentrations with height was observed up to thrice canopy height (i.e., 10 m). These homogeneous profiles indicate strong mixing near orchard and are in line with the unstable atmospheric conditions that prevailed during measurements. While air concentrations during pesticide application were higher than after it, overall pesticide load drifted from the orchard during primary and secondary drift are comparable. To the best of our knowledge this is the first work to show such large vertical dispersion and long duration of secondary drift following ground application in orchards. The obtained information indicates that secondary drift should not be neglected in exposure and environmental impact estimations. Copyright © 2017 Elsevier Ltd. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RScI...88b4102B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RScI...88b4102B">Shutterless ion mobility spectrometer with fast pulsed electron source</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bunert, E.; Heptner, A.; Reinecke, T.; Kirk, A. T.; Zimmermann, S. 2017-02-01 Ion mobility spectrometers (IMS) are devices for fast and very sensitive trace gas analysis. The measuring principle is based on an initial ionization process of the target analyte. Most IMS employ radioactive electron sources, such as 63Ni or 3H. These radioactive materials have the disadvantage of legal restrictions and the electron emission has a predetermined intensity and cannot be controlled or disabled. In this work, we replaced the 3H source of our IMS with 100 mm drift tube length with our nonradioactive electron source, which generates comparable spectra to the 3H source. An advantage of our emission current controlled nonradioactive electron source is that it can operate in a fast pulsed mode with high electron intensities. By optimizing the geometric parameters and developing fast control electronics, we can achieve very short electron emission pulses for ionization with high intensities and an adjustable pulse width of down to a few nanoseconds. This results in small ion packets at simultaneously high ion densities, which are subsequently separated in the drift tube. Normally, the required small ion packet is generated by a complex ion shutter mechanism. By omitting the additional reaction chamber, the ion packet can be generated directly at the beginning of the drift tube by our pulsed nonradioactive electron source with only slight reduction in resolving power. Thus, the complex and costly shutter mechanism and its electronics can also be omitted, which leads to a simple low-cost IMS-system with a pulsed nonradioactive electron source and a resolving power of 90. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25430326','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25430326">Silicon drift detector based X-ray spectroscopy diagnostic system for the study of non-thermal electrons at Aditya tokamak.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Purohit, S; Joisa, Y S; Raval, J V; Ghosh, J; Tanna, R; Shukla, B K; Bhatt, S B 2014-11-01 Silicon drift detector based X-ray spectrometer diagnostic was developed to study the non-thermal electron for Aditya tokamak plasma. The diagnostic was mounted on a radial mid plane port at the Aditya. The objective of diagnostic includes the estimation of the non-thermal electron temperature for the ohmically heated plasma. Bi-Maxwellian plasma model was adopted for the temperature estimation. Along with that the study of high Z impurity line radiation from the ECR pre-ionization experiments was also aimed. The performance and first experimental results from the new X-ray spectrometer system are presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PSST...27c5010K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PSST...27c5010K">Numerical analysis of azimuthal rotating spokes in a crossed-field discharge plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kawashima, R.; Hara, K.; Komurasaki, K. 2018-03-01 Low-frequency rotating spokes are obtained in a cross-field discharge plasma using two-dimensional numerical simulations. A particle-fluid hybrid model is used to model the plasma flow in a configuration similar to a Hall thruster. It has been reported that the drift-diffusion approximation for an electron fluid results in an ill-conditioned matrix when solving for the potential because of the differences in the electron mobilities across the magnetic field and in the direction of the E × B drift. In this paper, we employ a hyperbolic approach that enables stable calculation, namely, better iterative convergence of the electron fluid model. Our simulation results show a coherent rotating structure propagating in the E × B direction with a phase velocity of 2500 m s‑1, which agrees with experimental data. The phase velocity obtained from the numerical simulations shows good agreement with that predicted by the dispersion relation of the gradient drift instability. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active">10</li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active">11</li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.2978E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.2978E">Drift waves, intense parallel electric fields, and turbulence associated with asymmetric magnetic reconnection at the magnetopause</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ergun, R. E.; Chen, L.-J.; Wilder, F. D.; Ahmadi, N.; Eriksson, S.; Usanova, M. E.; Goodrich, K. A.; Holmes, J. C.; Sturner, A. P.; Malaspina, D. M.; Newman, D. L.; Torbert, R. B.; Argall, M. R.; Lindqvist, P.-A.; Burch, J. L.; Webster, J. M.; Drake, J. F.; Price, L.; Cassak, P. A.; Swisdak, M.; Shay, M. A.; Graham, D. B.; Strangeway, R. J.; Russell, C. T.; Giles, B. L.; Dorelli, J. C.; Gershman, D.; Avanov, L.; Hesse, M.; Lavraud, B.; Le Contel, O.; Retino, A.; Phan, T. D.; Goldman, M. V.; Stawarz, J. E.; Schwartz, S. J.; Eastwood, J. P.; Hwang, K.-J.; Nakamura, R.; Wang, S. 2017-04-01 Observations of magnetic reconnection at Earth's magnetopause often display asymmetric structures that are accompanied by strong magnetic field (B) fluctuations and large-amplitude parallel electric fields (E||). The B turbulence is most intense at frequencies above the ion cyclotron frequency and below the lower hybrid frequency. The B fluctuations are consistent with a thin, oscillating current sheet that is corrugated along the electron flow direction (along the X line), which is a type of electromagnetic drift wave. Near the X line, electron flow is primarily due to a Hall electric field, which diverts ion flow in asymmetric reconnection and accompanies the instability. Importantly, the drift waves appear to drive strong parallel currents which, in turn, generate large-amplitude ( 100 mV/m) E|| in the form of nonlinear waves and structures. These observations suggest that turbulence may be common in asymmetric reconnection, penetrate into the electron diffusion region, and possibly influence the magnetic reconnection process. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860025440&hterms=Exciter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DExciter','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860025440&hterms=Exciter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DExciter">Electrostatic ion-cyclotron waves in a nonuniform magnetic field</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cartier, S. L.; Dangelo, N.; Merlino, R. L. 1985-01-01 The properties of electrostatic ion-cyclotron waves excited in a single-ended cesium Q machine with a nonuniform magnetic field are described. The electrostatic ion-cyclotron waves are generated in the usual manner by drawing an electron current to a small exciter disk immersed in the plasma column. The parallel and perpendicular (to B) wavelengths and phase velocities are determined by mapping out two-dimensional wave phase contours. The wave frequency f depends on the location of the exciter disk in the nonuniform magnetic field, and propagating waves are only observed in the region where f is approximately greater than fci, where fci is the local ion-cyclotron frequency. The parallel phase velocity is in the direction of the electron drift. From measurements of the plasma properties along the axis, it is inferred that the electron drift velocity is not uniform along the entire current channel. The evidence suggests that the waves begin being excited at that axial position where the critical drift velocity is first exceeded, consistent with a current-driven excitation mechanism. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22493846-ion-beam-enhancement-magnetically-insulated-ion-diodes-high-intensity-pulsed-ion-beam-generation-non-relativistic-mode','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22493846-ion-beam-enhancement-magnetically-insulated-ion-diodes-high-intensity-pulsed-ion-beam-generation-non-relativistic-mode">Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Zhu, X. P.; Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024; Zhang, Z. C. High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, takingmore » into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25e3706S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25e3706S">Drift dust acoustic soliton in the presence of field-aligned sheared flow and nonextensivity effects</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shah, AttaUllah; Mushtaq, A.; Farooq, M.; Khan, Aurangzeb; Aman-ur-Rehman 2018-05-01 Low frequency electrostatic dust drift acoustic (DDA) waves are studied in an inhomogeneous dust magnetoplasma comprised of dust components of opposite polarity, Boltzmannian ions, and nonextensive distributed electrons. The magnetic-field-aligned dust sheared flow drives the electrostatic drift waves in the presence of ions and electrons. The sheared flow decreases or increases the frequency of the DDA wave, mostly depending on its polarity. The conditions of instability for this mode, with nonextensivity and dust streaming effects, are discussed. The nonlinear dynamics is then investigated for the DDA wave by deriving the Koeteweg-deVries (KdV) nonlinear equation. The KdV equation yields an electrostatic structure in the form of a DDA soliton. The relevancy of the work to laboratory four component dusty plasmas is illustrated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22614043-formation-space-charge-bunches-multivelocity-electron-beam-based-microwave-oscillator-cathode-unshielded-from-magnetic-field','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22614043-formation-space-charge-bunches-multivelocity-electron-beam-based-microwave-oscillator-cathode-unshielded-from-magnetic-field">Formation of space-charge bunches in a multivelocity-electron-beam-based microwave oscillator with a cathode unshielded from the magnetic field</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kalinin, Yu. A.; Starodubov, A. V.; Fokin, A. S., E-mail: alexander1989fokin@mail.ru The influence of the magnitude and configuration of the magnetic field on the parameters of electron bunches formed in a multivelocity electron beam is analyzed. It is shown that the use of a cathode unshielded from the magnetic field and a nonuniform magnetic field increasing along the drift space enables the formation of compact electron bunches. The ratio between the current density in such bunches and the beam current density at the entrance to the drift space reaches 10{sup 6}, which results in a substantial broadening of the output microwave spectrum due to an increase in the amplitudes of themore » higher harmonics of the fundamental frequency.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1402610','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1402610">Physical mechanism causing rapid changes in ultrarelativistic electron pitch angle distributions right after a shock arrival: Evaluation of an electron dropout event: Drift Shell Splitting on the Dayside</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Zhang, X. -J.; Li, W.; Thorne, R. M. Three mechanisms have been proposed to explain relativistic electron flux depletions (dropouts) in the Earth's outer radiation belt during storm times: adiabatic expansion of electron drift shells due to a decrease in magnetic field strength, magnetopause shadowing and subsequent outward radial diffusion, and precipitation into the atmosphere (driven by EMIC wave scattering). Which mechanism predominates in causing electron dropouts commonly observed in the outer radiation belt is still debatable. In the present study, we evaluate the physical mechanism that may be primarily responsible for causing the sudden change in relativistic electron pitch angle distributions during a dropout event observed bymore » Van Allen Probes during the main phase of the 27 February 2014 storm. During this event, the phase space density of ultrarelativistic (>1MeV) electrons was depleted by more than 1 order of magnitude over the entire radial extent of the outer radiation belt (3 < L* < 5) in less than 6 h after the passage of an interplanetary shock. We model the electron pitch angle distribution under a compressed magnetic field topology based on actual solar wind conditions. Although these ultrarelativistic electrons exhibit highly anisotropic (peaked in 90°), energy-dependent pitch angle distributions, which appear to be associated with the typical EMIC wave scattering, comparison of the modeled electron distribution to electron measurements indicates that drift shell splitting is responsible for this rapid change in electron pitch angle distributions. This further indicates that magnetopause loss is the predominant cause of the electron dropout right after the shock arrival.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1402610-physical-mechanism-causing-rapid-changes-ultrarelativistic-electron-pitch-angle-distributions-right-after-shock-arrival-evaluation-electron-dropout-event-drift-shell-splitting-dayside','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1402610-physical-mechanism-causing-rapid-changes-ultrarelativistic-electron-pitch-angle-distributions-right-after-shock-arrival-evaluation-electron-dropout-event-drift-shell-splitting-dayside">Physical mechanism causing rapid changes in ultrarelativistic electron pitch angle distributions right after a shock arrival: Evaluation of an electron dropout event: Drift Shell Splitting on the Dayside</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Zhang, X. -J.; Li, W.; Thorne, R. M.; ... 2016-08-13 Three mechanisms have been proposed to explain relativistic electron flux depletions (dropouts) in the Earth's outer radiation belt during storm times: adiabatic expansion of electron drift shells due to a decrease in magnetic field strength, magnetopause shadowing and subsequent outward radial diffusion, and precipitation into the atmosphere (driven by EMIC wave scattering). Which mechanism predominates in causing electron dropouts commonly observed in the outer radiation belt is still debatable. In the present study, we evaluate the physical mechanism that may be primarily responsible for causing the sudden change in relativistic electron pitch angle distributions during a dropout event observed bymore » Van Allen Probes during the main phase of the 27 February 2014 storm. During this event, the phase space density of ultrarelativistic (>1MeV) electrons was depleted by more than 1 order of magnitude over the entire radial extent of the outer radiation belt (3 < L* < 5) in less than 6 h after the passage of an interplanetary shock. We model the electron pitch angle distribution under a compressed magnetic field topology based on actual solar wind conditions. Although these ultrarelativistic electrons exhibit highly anisotropic (peaked in 90°), energy-dependent pitch angle distributions, which appear to be associated with the typical EMIC wave scattering, comparison of the modeled electron distribution to electron measurements indicates that drift shell splitting is responsible for this rapid change in electron pitch angle distributions. This further indicates that magnetopause loss is the predominant cause of the electron dropout right after the shock arrival.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661421-new-evidence-charge-sign-dependent-modulation-during-solar-minimum','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661421-new-evidence-charge-sign-dependent-modulation-during-solar-minimum">NEW EVIDENCE FOR CHARGE-SIGN-DEPENDENT MODULATION DURING THE SOLAR MINIMUM OF 2006 TO 2009</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Di Felice, V.; Munini, R.; Vos, E. E. The PAMELA space experiment, in orbit since 2006, has measured cosmic rays (CRs) through the most recent period of minimum solar activity with the magnetic field polarity as A < 0. During this entire time, galactic electrons and protons have been detected down to 70 MV and 400 MV, respectively, and their differential variation in intensity with time has been monitored with unprecedented accuracy. These observations are used to show how differently electrons and protons responded to the quiet modulation conditions that prevailed from 2006 to 2009. It is well known that particle drifts, as one of four major mechanisms for the solarmore » modulation of CRs, cause charge-sign-dependent solar modulation. Periods of minimum solar activity provide optimal conditions in which to study these drift effects. The observed behavior is compared to the solutions of a three-dimensional model for CRs in the heliosphere, including drifts. The numerical results confirm that the difference in the evolution of electron and proton spectra during the last prolonged solar minimum is attributed to a large extent to particle drifts. We therefore present new evidence of charge-sign-dependent solar modulation, with a perspective on its peculiarities for the observed period from 2006 to 2009.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25d2111I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25d2111I">Existence regimes for shocks in inhomogeneous magneto-plasmas having entropy</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Iqbal, Javed; Yaqub Khan, M. 2018-04-01 The finding of connection of plasma density and temperature with entropy gives an incitement to study different plasma models with respect to entropy. Nonlinear dissipative one- and two-dimensional structures (shocks) are investigated in nonuniform magnetized plasma with respect to entropy. The dissipation comes in the medium through ion-neutral collisions. The linear dispersion relation is derived. The Korteweg-deVries-Burgers and Kadomtsev-Petviashvili-Burgers equations are derived for nonlinear drift waves in 1-D and 2-D by employing the drift approximation. It is found that vd/u ( vd is the diamagnetic drift velocity and u is the velocity of nonlinear structure) plays a significant role in the shock formation. It is also found that entropy has a significant effect on the strength of shocks. It is noticed that v d/u determines the rarefactive and compressive nature of the shocks. It is observed that upper and lower bounds exist for the shock velocity. It is also observed that the existing regimes for both one- and two-dimensional shocks for kappa distributed electrons are different from shocks with Cairns distributed electrons. Both rarefactive and compressive shocks are found for the 1-D drift waves with kappa distributed electrons. Interestingly, it is noticed that entropy enhances the strength of one- and two-dimensional shocks. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvL.119y8101D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvL.119y8101D">Filament Tension and Phase Locking of Meandering Scroll Waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dierckx, Hans; Biktasheva, I. V.; Verschelde, H.; Panfilov, A. V.; Biktashev, V. N. 2017-12-01 Meandering spiral waves are often observed in excitable media such as the Belousov-Zhabotinsky reaction and cardiac tissue. We derive a theory for drift dynamics of meandering rotors in general reaction-diffusion systems and apply it to two types of external disturbances: an external field and curvature-induced drift in three dimensions. We find two distinct regimes: with small filament curvature, meandering scroll waves exhibit filament tension, whose sign determines the stability and drift direction. In the regimes of strong external fields or meandering motion close to resonance, however, phase locking of the meander pattern is predicted and observed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29917229','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29917229">Digest: Local adaptation at close quarters.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Schmidt, Chloé; Garroway, Colin 2018-06-19 Although the theory of how gene flow and genetic drift interact with local adaptation is well understood, few empirical studies have examined this process. Hämälä et al. (2018) present evidence that adaptive divergence between populations of Arabidopsis lyrata can persist in the face of relatively high levels of gene flow and drift. Maintaining divergence despite gene flow and drift has important implications for understanding adaptive responses of populations in response to human-driven environmental change. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29303350','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29303350">Filament Tension and Phase Locking of Meandering Scroll Waves.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Dierckx, Hans; Biktasheva, I V; Verschelde, H; Panfilov, A V; Biktashev, V N 2017-12-22 Meandering spiral waves are often observed in excitable media such as the Belousov-Zhabotinsky reaction and cardiac tissue. We derive a theory for drift dynamics of meandering rotors in general reaction-diffusion systems and apply it to two types of external disturbances: an external field and curvature-induced drift in three dimensions. We find two distinct regimes: with small filament curvature, meandering scroll waves exhibit filament tension, whose sign determines the stability and drift direction. In the regimes of strong external fields or meandering motion close to resonance, however, phase locking of the meander pattern is predicted and observed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SFZ.....4a..59L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SFZ.....4a..59L">Electron radiation belt dynamics during magnetic storms and in quiet time</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lazutin, Leonid; Dmitriev, Aleksey; Suvorova, Alla 2018-03-01 The paper discusses the dynamics of the outer electron belt, adiabatic and nonadiabatic mechanisms of replenishment and losses of energetic electrons. Under undisturbed conditions, the outer electron belt gradually empties: in the inner magnetosphere due to electron precipitation in the atmosphere and in the quasi-trapping region due to losses at the magnetopause because drift shells of electrons are not closed there. The latter process does not occur in normal years due to the masking replenishment by freshly accelerated particles, but in years of extremely low activity, it leads to a significant decrease in the electron population of the belt. During the magnetic storm main phase, the first reason for the decrease in the electron flux intensity is the adiabatic cooling associated with conservation of adiabatic invariants and complemented by precipitation of electrons into the atmosphere and their dropout at the magnetopause. Electron flux increases involve E×B electron injection by the induction electric field of substorm activation and by the large-scale solar wind electric field, with pitch energy diffusion along with adiabatic heating in the recovery phase. The rate of electron flux recovery after a storm is determined by the ratio of nonadiabatic increases and losses; hence the electron flux represents a continuous series from low to very high values. The combination of these processes determines the individual character of radiation belt development during each magnetic storm and the behavior of the belt in the quiet time. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22089291-role-ionization-electron-drift-velocity-profile-rayleigh-instability-hall-thruster-plasma','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22089291-role-ionization-electron-drift-velocity-profile-rayleigh-instability-hall-thruster-plasma">Role of ionization and electron drift velocity profile to Rayleigh instability in a Hall thruster plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Singh, Sukhmander; Malik, Hitendra K. Role of ionization to Rayleigh instability is clarified in a Hall thruster plasma under the variety of profiles of electron drift velocity, namely, step-like profile (SLP) and two different super-Gaussian profiles (SGP1 and SGP2). For this, a relevant Rayleigh equation is derived and solved numerically using fourth-order Runge-Kutta method. Interestingly, an upper cutoff frequency of oscillations {omega}{sub max} is realized for the occurrence of the instability that shows dependence on the ionization rate {alpha}, electron drift velocity u{sub 0}, electron cyclotron frequency {Omega}, azimuthal wave number k{sub y}, plasma density n{sub 0}, density gradient {partial_derivative}n{sub 0}/{partial_derivative}x, ion (electron) thermal speedmore » V{sub thI}(V{sub thE}), and ion (electron) plasma frequency {omega}{sub pi}({omega}{sub pe}). The frequency {omega}{sub max} follows the trend {omega}{sub max} (for SGP2) >{omega}{sub max} (for SLP) >{omega}{sub max} (for SGP1) and shows a similar behaviour with ionization for all types of the velocity profiles. The instability is found to grow faster for the higher {alpha} and the ion temperature but it acquires lower rate under the effect of the higher electron temperature; the perturbed potential also varies in accordance with the growth rate. The electron temperature influences the growth rate and cutoff frequency less significantly in comparison with the ion temperature.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..4311484F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..4311484F">Drift paths of ions composing multiple-nose spectral structures near the inner edge of the plasma sheet</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G.; Skoug, R.; Funsten, H. 2016-11-01 We present a case study of the H+, He+, and O+ multiple-nose structures observed by the Helium, Oxygen, Proton, and Electron instrument on board Van Allen Probe A over one complete orbit on 28 September 2013. Nose structures are observed near the inner edge of the plasma sheet and constitute the signatures of ion drift in the highly dynamic environment of the inner magnetosphere. We find that the multiple noses are intrinsically associated with variations in the solar wind. Backward ion drift path tracings show new details of the drift trajectories of these ions; i.e., multiple noses are formed by ions with a short drift time from the assumed source location to the inner region and whose trajectories (1) encircle the Earth different number of times or (2) encircle the Earth equal number of times but with different drift time, before reaching the observation site. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26436770','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26436770">Wave-driven butterfly distribution of Van Allen belt relativistic electrons.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D N; Spence, H E; Funsten, H O; Blake, J B 2015-10-05 Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day-night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920067258&hterms=environnement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Denvironnement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920067258&hterms=environnement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Denvironnement">Observations of the structure and vertical transport of the polar upper ionosphere with the EISCAT VHF radar. II - First investigations of the topside O(+) and H(+) vertical ion flows</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Wu, Jian; Blanc, Michel; Alcayde, Denis; Barakat, Abdullah R.; Fontanari, Jean; Blelly, Pierre-Louis; Kofman, Wlodek 1992-01-01 EISCAT VHF radar was used to investigate the vertical flows of H(+) and O(+) ions in the topside high-latitude ionosphere. The radar transmitted a single long pulse to probe the ionosphere from 300 to 1200 km altitude. A calculation scheme is developed to deduce the H(+) drift velocity from the coupled momentum equations of H(+), O(+), and the electrons, using the radar data and a neutral atmosphere model. The H(+) vertical drift velocity was expressed as a linear combination of the different forces acting on the plasma. Two nights, one very quiet, one with moderate magnetic activity, were used to test the technique and to provide a first study of the morphology and orders of magnitudes of ion outflow fluxes over Tromso. O(+) vertical flows were found to be downward or close to zero most of the time in the topside ionosphere; they appeared to be strongly correlated with magnetic activity during the disturbed night. H(+) topside ion fluxes were always directed upward, with velocity reaching 500-1000 m/s. A permanent outflow of H(+) ions is inferred. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH33A4144M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH33A4144M">Kinetic Effects in Parametric Instabilities of Finite Amplitude Alfven Waves in a Drifting Multi-Species Plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Maneva, Y. G.; Araneda, J. A.; Poedts, S. 2014-12-01 We consider parametric instabilities of finite-amplitude large-scale Alfven waves in a low-beta collisionless multi-species plasma, consisting of fluid electrons, kinetic protons and a drifting population of minor ions. Complementary to many theoretical studies, relying on fluid or multi-fluid approach, in this work we present the solutions of the parametric instability dispersion relation, including kinetic effects in the parallel direction, along the ambient magnetic field. This provides us with the opportunity to predict the importance of some wave-particle interactions like Landau damping of the daughter ion-acoustic waves for the given pump wave and plasma conditions. We apply the dispersion relation to plasma parameters, typical for low-beta collisionless solar wind close to the Sun. We compare the analytical solutions to the linear stage of hybrid numerical simulations and discuss the application of the model to the problems of preferential heating and differential acceleration of minor ions in the solar corona and the fast solar wind. The results of this study provide tools for prediction and interpretation of the magnetic field and particles data as expected from the future Solar Orbiter and Solar Probe Plus missions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1144...15S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1144...15S">Electron acceleration via magnetic island coalescence</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shinohara, I.; Yumura, T.; Tanaka, K. G.; Fujimoto, M. 2009-06-01 Electron acceleration via fast magnetic island coalescence that happens as quick magnetic reconnection triggering (QMRT) proceeds has been studied. We have carried out a three-dimensional full kinetic simulation of the Harris current sheet with a large enough simulation run for two magnetic islands coalescence. Due to the strong inductive electric field associated with the non-linear evolution of the lower-hybrid-drift instability and the magnetic island coalescence process observed in the non-linear stage of the collisionless tearing mode, electrons are significantly accelerated at around the neutral sheet and the subsequent X-line. The accelerated meandering electrons generated by the non-linear evolution of the lower-hybrid-drift instability are resulted in QMRT, and QMRT leads to fast magnetic island coalescence. As a whole, the reconnection triggering and its transition to large-scale structure work as an effective electron accelerator. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5508092-energetic-particle-drift-motions-outer-dayside-magnetosphere','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5508092-energetic-particle-drift-motions-outer-dayside-magnetosphere">Energetic-particle drift motions in the outer dayside magnetosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Buck, R.C. 1987-01-01 Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B pockets in the geomagnetic field. These pockets are theoretically capable of temporarily trapping azimuthally-drifting electrons and modifying electron directional distributions. The Lawrence Livermore National Laboratory's scanning electron spectrometer aboard the OGO-5 satellite provided detailed energetic (E > 70 keV) electron pitch-angle distributions throughout the magnetosphere. Distributions obtained in the outer dayside magnetosphere over a wide range of longitudes show unusual flux features. This study analyzes drift-shell branching caused by themore » minimum-B pockets, and interprets the observed flux features in terms of an adiabatic-shell branching and rejoining process. The author examines the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field mode. He finds that shell branching and rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. He also finds a good correlation between the itch angles that mark the transition from branched to unbranched shells in the model and the distinctive features of the OGO-5 distributions.« less </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active">11</li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active">12</li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000QuEle..30..483A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000QuEle..30..483A">IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Discharge characteristics in a nonchain HF(DF) laser</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Apollonov, V. V.; Kazantsev, S. Yu; Saifulin, A. V.; Firsov, K. N. 2000-06-01 It is found that for SF6—hydrocarbon (deuterocarbon) mixtures having a composition typical for nonchain HF(DF) lasers, the electric field strength reduced to the partial pressure of SF6 (pSF6) in the quasistationary phase of a volume self-sustained discharge (E/pSF6)st=92 V m-1 Pa-1 is close to the known critical value (E/p)cr=89 V m-1 Pa-1, which is specified by the condition that the electron-impact ionisation rate of SF6 is equal to the rate of electron attachment to SF6 molecules. This testifies to the decisive role of these two processes and allows the use of the known approximations of the effective ionisation coefficient and the electron drift velocity for pure SF6 when calculating the discharge characteristics. The oscilloscope traces of voltage and current calculated in this approximation for lasers with apertures ranging from 4 to 27 cm deviated from the experimental data by no more than 10%. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM42A..09T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM42A..09T">The Importance of Electron Source Population to the Remarkable Enhancement of Radiation belt Electrons during the October 2012 Storm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, W.; Cunningham, G.; Reeves, G. D.; Chen, Y.; Henderson, M. G.; Blake, J. B.; Baker, D. N.; Spence, H. 2013-12-01 During the October 8-9 2012 storm, the MeV electron fluxes in the heart of the outer radiation belt are first wiped out then exhibit a three-orders-of-magnitude increase on the timescale of hours, as observed by the MagEIS and REPT instruments aboard the Van Allen Probes. There is strong observational evidence that the remarkable enhancement is due to local acceleration by chorus waves, as shown in the recent Science paper by Reeves et al.1. However, the importance of the dynamic electron source population transported in from the plasma sheet, to the observed remarkable enhancement, has not been studied. We illustrate the importance of the source population with our simulation of the event using the DREAM 3D diffusion model. Three new modifications have been implemented in the model: 1) incorporating a realistic and time-dependent low-energy boundary condition at 100 keV obtained from the MagEIS data; 2) utilizing event-specific chorus wave distributions derived from the low-energy electron precipitation observed by POES and validated against the in situ wave data from EMFISIS; 3) using an ';open' boundary condition at L*=11 and implementing electron lifetimes on the order of the drift period outside the solar-wind driven last closed drift shell. The model quantitatively reproduces the MeV electron dynamics during this event, including the fast dropout at the start of Oct. 8th, low electron flux during the first Dst dip, and the remarkable enhancement peaked at L*=4.2 during the second Dst dip. By comparing the model results with realistic source population against those with constant low-energy boundary (see figure), we find that the realistic electron source population is critical to reproduce the observed fast and significant increase of MeV electrons. 1Reeves, G. D., et al. (2013), Electron Acceleration in the Heart of the Van Allen Radiation Belts, Science, DOI:10.1126/science.1237743. Comparison between data and model results during the October 2012 storm for electrons at μ=3168 MeV/G and K=0.1 G1/2Re. Top plot is the electron phase space density data measured by the two Van Allen Probes; middle plot shows the results from the DREAM 3D diffusion model with a realistic electron source population derived from MagEIS data; and the bottom plot is the model results with a constant source population. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.1178K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.1178K">An Energetic Electron Flux Dropout Due to Magnetopause Shadowing on 1 June 2013</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kang, Suk-Bin; Fok, Mei-Ching; Komar, Colin; Glocer, Alex; Li, Wen; Buzulukova, Natalia 2018-02-01 We examine the mechanisms responsible for the dropout of energetic electron flux during 31 May to 1 June 2013 using Van Allen Probe (Radiation Belt Storm Probes (RBSP)) electron flux data and simulations with the Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. During the storm main phase, L-shells at RBSP locations are greater than 8, which are connected to open drift shells. Consequently, diminished electron fluxes were observed over a wide range of energies. The combination of drift shell splitting, magnetopause shadowing, and drift loss all results in butterfly electron pitch angle distributions (PADs) at the nightside. During storm sudden commencement, RBSP observations display electron butterfly PADs over a wide range of energies. However, it is difficult to determine whether there are butterfly PADs during the storm main phase since the maximum observable equatorial pitch angle from RBSP is not larger than 40° during this period. To investigate the causes of the dropout, the CIMI model is used as a global 4-D kinetic inner magnetosphere model. The CIMI model reproduces the dropout with very similar timing and flux levels and PADs along the RBSP trajectory for 593 keV. Furthermore, the CIMI simulation shows butterfly PADs for 593 keV during the storm main phase. Based on comparison of observations and simulations, we suggest that the dropout during this event mainly results from magnetopause shadowing. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5928360-penetration-boundary-solar-cosmic-rays-earth-magnetosphere-during-magnetically-quiet-times','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5928360-penetration-boundary-solar-cosmic-rays-earth-magnetosphere-during-magnetically-quiet-times">Penetration boundary of solar cosmic rays into the earth's magnetosphere during magnetically quiet times</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Biryukov, A.S.; Ivanova, T.A.; Kovrygina, L.M. 1984-05-01 Data is used from the satellites Interkosmos-17 and Kosmos-900 to determine penetration boundaries at high latitudes in the earth's magnetosphere. Considered are the results of observations of the penetration boundary of solar cosmic ray (SCR) protons and electrons during an SCR increase on November 22-25, 1977. The position of the SCR penetration boundary during a single increase at practically all values of MLT in quiet conditions is examined. Magnetospheric structure is determined in the region of closed drift shells where the magnetic field is asymmetric. The authors can estimate how the solar wind pressure affects the magnetosphere by using datamore » on the penetration boundaries of solar protons obtained during quiet geomagnetic conditions.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..148a2019M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..148a2019M">Multi-criteria optimization of chassis parameters of Nissan 200 SX for drifting competitions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Maniowski, M. 2016-09-01 The work objective is to increase performance of Nissan 200sx S13 prepared for a quasi-static state of drifting on a circular path with given constant radius (R=15 m) and tyre-road friction coefficient (μ = 0.9). First, a high fidelity “miMA” multibody model of the vehicle is formulated. Then, a multicriteria optimization problem is solved with one of the goals to maximize a stable drift angle (β) of the vehicle. The decision variables contain 11 parameters of the vehicle chassis (describing the wheel suspension stiffness and geometry) and 2 parameters responsible for a driver steering and accelerator actions, that control this extreme closed-loop manoeuvre. The optimized chassis setup results in the drift angle increase by 14% from 35 to 40 deg. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.T51E0527S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.T51E0527S">Laboratory Simulation and Measurement of Instrument Drift in Quartz-Resonant Pressure Gauges</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sasagawa, G. S.; Zumberge, M. A. 2017-12-01 Marine geodesy uses ocean bottom pressure sensors to measure vertical deformation of the sea floor, including that due to volcanic inflation and subsidence, episodic tremor and slip, plate subduction, and deformation due to hydrocarbon extraction at offshore reservoirs. Instrumental drift is inherent in existing pressure sensors and introduce uncertainties in data interpretation. Different methods have been developed to control drift, using varying techniques and instrumentation. Laboratory measurements of sensor drift, under controlled conditions that simulate seafloor pressures and temperatures, would allow for evaluating pressure gauge drift and the efficacy of new drift control methods. We have constructed and operated a laboratory system to monitor the drift of 15 quartz resonant pressure gauges over a year. The temperature and pressure are maintained and controlled at approximately 5 °C and 1900 dbar. A deadweight tester was used to provide a reference signal at frequent intervals; the time series of reference pressure signals is a direct measure of each gauge's drift. Several other tests were conducted, including a) evaluation of a custom outgassing sensor used as proxy for instrument drift, b) determination of the oscillator drift in the pressure gauge signal conditioning electronics, and c) a test of ambient air pressure calibration, also known as the A-0-A method. First results will be presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24713344','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24713344">Phase measurement error in summation of electron holography series.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> McLeod, Robert A; Bergen, Michael; Malac, Marek 2014-06-01 Off-axis electron holography is a method for the transmission electron microscope (TEM) that measures the electric and magnetic properties of a specimen. The electrostatic and magnetic potentials modulate the electron wavefront phase. The error in measurement of the phase therefore determines the smallest observable changes in electric and magnetic properties. Here we explore the summation of a hologram series to reduce the phase error and thereby improve the sensitivity of electron holography. Summation of hologram series requires independent registration and correction of image drift and phase wavefront drift, the consequences of which are discussed. Optimization of the electro-optical configuration of the TEM for the double biprism configuration is examined. An analytical model of image and phase drift, composed of a combination of linear drift and Brownian random-walk, is derived and experimentally verified. The accuracy of image registration via cross-correlation and phase registration is characterized by simulated hologram series. The model of series summation errors allows the optimization of phase error as a function of exposure time and fringe carrier frequency for a target spatial resolution. An experimental example of hologram series summation is provided on WS2 fullerenes. A metric is provided to measure the object phase error from experimental results and compared to analytical predictions. The ultimate experimental object root-mean-square phase error is 0.006 rad (2π/1050) at a spatial resolution less than 0.615 nm and a total exposure time of 900 s. The ultimate phase error in vacuum adjacent to the specimen is 0.0037 rad (2π/1700). The analytical prediction of phase error differs with the experimental metrics by +7% inside the object and -5% in the vacuum, indicating that the model can provide reliable quantitative predictions. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PlPhR..44..453G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PlPhR..44..453G">Characteristics of Electron Drift in an Ar-Hg Mixture</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Golyatina, R. I.; Maiorov, S. A. 2018-04-01 The characteristics of electron drift in a mixture of argon with mercury vapor at reduced electric fields of E/ N = 1-100 Td are calculated and analyzed with allowance for inelastic collisions. It is shown that even a minor additive of mercury to argon at a level of a fraction of percent substantially affects the discharge parameters, in particular, the characteristics of inelastic processes. The influence of the concentration of mercury vapor in argon on the kinetic characteristics, such as the diffusion and mobility coefficients and ionization frequency, is investigated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM43B2720K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM43B2720K">Characteristics of pitch angle distributions of relativistic electrons under the interaction with Pc5 waves in the inner magnetosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kamiya, K.; Seki, K.; Saito, S.; Amano, T.; Yoshizumi, M. 2017-12-01 Radial transport of relativistic electrons in the inner magnetosphere has been considered as one of acceleration mechanisms of the outer radiation belt electrons and can be driven by the drift resonance with ULF waves in the Pc5 frequency range. The maximum changes of the electron in the radial distance (L) due to the drift resonance depend on the electron energy, pitch angle, and Pc5 wave structure. Those dependences are expected to form the characteristic pitch angle distributions (PADs) as a function of L and electron energy. In this study, we investigate PADs of relativistic electrons due to the drift resonance with a monochromatic Pc5 wave by using two simulation models of the inner magnetosphere: GEMSIS-Ring Current (RC) and GEMSIS-Radiation Belt (RB) models. The GEMSIS-RB simulations calculate guiding center trajectories of relativistic electrons in electric and magnetic fields obtained from the GEMSIS-RC model, which simulates a monochromatic Pc5 wave propagation in the inner magnetosphere. The results show the characteristic PADs depending on the energy and L, which is explicable with the pitch angle dependence of resonance conditions. At a fixed location, those PADs can change from pancake (90°peaked) to butterfly (two peaks in oblique PAs) distributions as the transport by the monochromatic Pc5 wave progresses. These butterfly distributions are seen in the L range where electrons with lower PAs satisfy the resonance condition. It is also found that the lower PA electron with a fixed magnetic moment can be transported deeper inside because of the PA changes to larger values through the adiabatic transport, which enables them to satisfy the efficient resonance condition in wider L range compared to the 90 degrees PA electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM21B2521T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM21B2521T">Study the Precipitation of Radiation Belt Electrons during the Rapid Dropout Events</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tu, W.; Cunningham, G.; Li, X.; Chen, Y. 2015-12-01 During the main phase of storms, the relativistic electron flux in the radiation belt can drop by orders of magnitude on timescales of a few hours. Where do the electrons go? This is one of the most important outstanding questions in radiation belt studies. Radiation belt electrons can be lost either by transport across the magnetopause into interplanetary space or by precipitation into the atmosphere. In this work we first conduct a survey of the MeV electron dropouts using the Van Allen Probes data in conjunction with the low-altitude measurements of precipitating electrons by 6 NOAA/POES satellites. The dropout events are categorized into three types: precipitation-loss dominant, outward radial diffusion dominant, or with contributions from both mechanisms. The survey results suggest the relative importance of precipitation and outward radial diffusion to the fast dropouts of radiation belt electrons, and their extent in L-shell and electron energy. Then, for specific events identified as dominated by precipitation loss, we use the Drift-Diffusion model, which includes the effects of azimuthal drift and pitch angle diffusion, to simulate both the electron dropout observed by Van Allen Probes and the distributions of drift-loss-cone electrons observed by multiple low-earth-orbit satellites (6 POES and the Colorado Student Space Weather Experiment). The model quantifies the electron precipitation loss and pitch angle diffusion coefficient, Dxx, with high temporal and spatial resolution. Finally, by comparing the Dxx derived from the model with those estimated from the quasi-linear theory using wave data from Van Allen Probes and other event-specific wave models, we are able to test the validity of quasi-linear theory and seek direct evidence of the wave-particle interactions during the dropouts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007MNRAS.377L..10B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007MNRAS.377L..10B">Discovery of a remarkable subpulse drift pattern in PSR B0818-41</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bhattacharyya, B.; Gupta, Y.; Gil, J.; Sendyk, M. 2007-05-01 We report the discovery of a remarkable subpulse drift pattern in the relatively less-studied wide profile pulsar B0818-41 using high-sensitivity Giant Metrewave Radio Telescope (GMRT) observations. We find simultaneous occurrences of three drift regions with two different drift rates: an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, these closely spaced drift bands always maintain a constant phase relationship. Though these drift regions have significantly different values for the measured P2, the measured P3 value is the same and equal to 18.3P1. We interpret the unique drift pattern of this pulsar as being created by the intersection of our line of sight (LOS) with two conal rings on the polar cap of a fairly aligned rotator (inclination angle α ~ 11°), with an `inner' LOS geometry (impact angle ). We argue that both rings have the same values for the carousel rotation periodicity P4 and the number of sparks Nsp. We find that Nsp is 19-21 and show that it is very likely that P4 is the same as the measured P3, making it a truly unique pulsar. We present results from simulations of the radiation pattern using the inferred parameters, which support our interpretations and reproduce the average profile as well as the observed features in the drift pattern quite well. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/570425','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/570425">Discrete monotron oscillator having one-half wavelength coaxial resonator with one-quarter wavelength gap spacing</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Carlsten, B.E.; Haynes, W.B. 1998-02-03 A discrete monotron oscillator for use in a high power microwave device is formed with a microwave oscillator having a half-wavelength resonant coaxial microwave cavity operating in fundamental TEM mode for microwave oscillation with an inner conductor defining a drift tube for propagating an electron beam and an outer conductor coaxial with the inner conductor. The inner conductor defines a modulating gap and an extraction gap downstream of the modulating gap. The modulating gap and the extraction gap connect the coaxial microwave cavity with the drift tube so that energy for the microwave oscillation is extracted from the electron beam at the extraction gap and modulates the electron beam at the modulating gap. For high power operation, an annular electron beam is used. 8 figs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/871355','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/871355">Discrete monotron oscillator having one-half wavelength coaxial resonator with one-quarter wavelength gap spacing</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Carlsten, Bruce E.; Haynes, William B. 1998-01-01 A discrete monotron oscillator for use in a high power microwave device is formed with a microwave oscillator having a half-wavelength resonant coaxial microwave cavity operating in fundamental TEM mode for microwave oscillation with an inner conductor defining a drift tube for propagating an electron beam and an outer conductor coaxial with the inner conductor. The inner conductor defines a modulating gap and an extraction gap downstream of the modulating gap. The modulating gap and the extraction gap connect the coaxial microwave cavity with the drift tube so that energy for the microwave oscillation is extracted from the electron beam at the extraction gap and modulates the electron beam at the modulating gap. For high power operation, an annular electron beam is used. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/201765','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/201765">Measurement of the dynamo effect in a plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ji, H.; Prager, S.C.; Almagri, A.F. 1995-11-01 A series of the detailed experiments has been conducted in three laboratory plasma devices to measure the dynamo electric field along the equilibrium field line (the {alpha} effect) arising from the correlation between the fluctuating flow velocity and magnetic field. The fluctuating flow velocity is obtained from probe measurement of the fluctuating E x B drift and electron diamagnetic drift. The three major findings are (1) the {alpha} effect accounts for the dynamo current generation, even in the time dependence through a ``sawtooth`` cycle; (2) at low collisionality the dynamo is explained primarily by the widely studied pressureless Magnetohydrodynamic (MHD)more » model, i.e., the fluctuating velocity is dominated by the E x B drift; (3) at high collisionality, a new ``electron diamagnetic dynamo`` is observed, in which the fluctuating velocity is dominated by the diamagnetic drift. In addition, direct measurements of the helicity flux indicate that the dynamo activity transports magnetic helicity from one part of the plasma to another, but the total helicity is roughly conserved, verifying J.B. Taylor`s conjecture.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599038-collisional-transport-across-magnetic-field-drift-fluid-models','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599038-collisional-transport-across-magnetic-field-drift-fluid-models">Collisional transport across the magnetic field in drift-fluid models</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Madsen, J., E-mail: jmad@fysik.dtu.dk; Naulin, V.; Nielsen, A. H. 2016-03-15 Drift ordered fluid models are widely applied in studies of low-frequency turbulence in the edge and scrape-off layer regions of magnetically confined plasmas. Here, we show how collisional transport across the magnetic field is self-consistently incorporated into drift-fluid models without altering the drift-fluid energy integral. We demonstrate that the inclusion of collisional transport in drift-fluid models gives rise to diffusion of particle density, momentum, and pressures in drift-fluid turbulence models and, thereby, obviates the customary use of artificial diffusion in turbulence simulations. We further derive a computationally efficient, two-dimensional model, which can be time integrated for several turbulence de-correlation timesmore » using only limited computational resources. The model describes interchange turbulence in a two-dimensional plane perpendicular to the magnetic field located at the outboard midplane of a tokamak. The model domain has two regions modeling open and closed field lines. The model employs a computational expedient model for collisional transport. Numerical simulations show good agreement between the full and the simplified model for collisional transport.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...612L...5O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...612L...5O">Formation of the terrestrial planets in the solar system around 1 au via radial concentration of planetesimals</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ogihara, Masahiro; Kokubo, Eiichiro; Suzuki, Takeru K.; Morbidelli, Alessandro 2018-05-01 Context. No planets exist inside the orbit of Mercury and the terrestrial planets of the solar system exhibit a localized configuration. According to thermal structure calculation of protoplanetary disks, a silicate condensation line ( 1300 K) is located around 0.1 au from the Sun except for the early phase of disk evolution, and planetesimals could have formed inside the orbit of Mercury. A recent study of disk evolution that includes magnetically driven disk winds showed that the gas disk obtains a positive surface density slope inside 1 au from the central star. In a region with positive midplane pressure gradient, planetesimals undergo outward radial drift. Aims: We investigate the radial drift of planetesimals and type I migration of planetary embryos in a disk that viscously evolves with magnetically driven disk winds. We show a case in which no planets remain in the close-in region. Methods: Radial drifts of planetesimals are simulated using a recent disk evolution model that includes effects of disk winds. The late stage of planet formation is also examined by performing N-body simulations of planetary embryos. Results: We demonstrate that in the middle stage of disk evolution, planetesimals can undergo convergent radial drift in a magnetorotational instability (MRI)-inactive disk, in which the pressure maximum is created, and accumulate in a narrow ring-like region with an inner edge at 0.7 au from the Sun. We also show that planetary embryos that may grow from the narrow planetesimal ring do not exhibit significant type I migration in the late stage of disk evolution. Conclusions: The origin of the localized configuration of the terrestrial planets of the solar system, in particular the deficit of close-in planets, can be explained by the convergent radial drift of planetesimals in disks with a positive pressure gradient in the close-in region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..GECAM2008B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..GECAM2008B">Cross-field diffusion in Hall thrusters and other plasma thrusters</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Boeuf, J. P. 2012-10-01 Understanding and quantifying electron transport perpendicular to the magnetic field is a challenge in many low temperature plasma applications. Hall effect thrusters (HETs) provide an excellent example of cross-field transport. The HET is a very successful concept that can be considered both as a gridless ion source and an electromagnetic thruster. In HETs, the electric field E accelerating the ions is a consequence of the Lorentz force due to an external magnetic field B acting on the ExB Hall electron current. An essential aspect of HETs is that the ExB drift is closed, i.e. is in the azimuthal direction of a cylindrical channel. In the first part of this presentation we will discuss the physics of cross-field electron transport in HETs, and the current understanding (or non-understanding) of the possible role of turbulence and wall collisions on cross-field diffusion. We will also briefly comment on alternative designs of ion sources based on the same principles as the conventional HET (Anode Layer Thruster, Diverging Cusp Field Thrusters, End-Hall ion sources). In a second part of the presentation we show that the Lorentz force acting on diamagnetic currents (associated with the ∇PexB term in the electron momentum equation) can also provide thrust. This is the case for example in helicon thrusters where the plasma expands in a magnetic nozzle. We will report and discuss recent work on helicon thrusters and other devices where the diamagnetic current is dominant (with some examples where the ∇PexB current is not closed and is directed toward a wall!). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPA43A2181M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPA43A2181M">Community Air Monitoring for Pesticide Drift Using Pesticide Action Network's (PAN) Drift Catcher</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Marquez, E. 2016-12-01 Community air monitoring projects for pesticides in the air have been conducted by PAN in collaboration with community members and locally based groups engaged around pesticide issues. PAN is part of an international network working to promote a just, thriving food system and replace the use of hazardous pesticides with ecologically sound alternatives. The Drift Catcher is an air-monitoring device with a design based on the California Air Resource Board's air monitoring equipment, and has been used in community-based projects in 11 states. Observations of pesticide drift made by community members cannot always be confirmed by regulatory agencies—if an inspection is made hours or days after a drift incident, the evidence may no longer be present. The Drift Catcher makes it possible to collect scientific evidence of pesticide drift in areas where people live, work, and play. One of the most recent Drift Catcher projects was done in California, in partnership with the Safe Strawberry Coalition and led by the statewide coalition Californians for Pesticide Reform. The data were used to support a call for stronger mitigation rules for the fumigant chloropicrin and to support a campaign asking for stronger pesticide rules to protect children attending school in close proximity to agricultural fields. The Drift Catcher data are used by organizers and community members to engage policymakers with the intention of making policy change on a local and/or statewide level. On the national level, PAN's Drift Catcher data has helped win regulatory recognition of volatilization drift for pesticides other than fumigants. Lessons learned from conducting community-based research projects will also be discussed. PAN is also currently assessing other community-based monitoring tools, such as community surveys and drift questionnaires that may allow communities to collect data that can also support the campaign work. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012cosp...39.1421O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012cosp...39.1421O">Relationship between vertical ExB drift and F2-layer characteristics in the equatorial ionosphere at solar minimum conditions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Oyekola, Oyedemi S. 2012-07-01 Equatorial and low-latitude electrodynamics plays a dominant role in determining the structure and dynamics of the equatorial and low-latitude ionospheric F-region. Thus, they constitute essential input parameters for quantitative global and regional modeling studies. In this work, hourly median value of ionosonde measurements namely, peak height F2-layer (hmF2), F2-layer critical frequency (foF2) and propagation factor M(3000)F2 made at near equatorial dip latitude, Ouagadougou, Burkina Faso (12oN, 1.5oW; dip: 1.5oN) and relevant F2-layer parameters such as thickness parameter (Bo), electron temperature (Te), ion temperature (Ti), total electron content (TEC) and electron density (Ne, at the fixed altitude of 300 km) provided by the International Reference Ionosphere (IRI) model for the longitude of Ouagadougou are contrasted with the IRI vertical drift model to explore in detail the monthly climatological behavior of equatorial ionosphere and the effects of equatorial vertical plasma drift velocities on the diurnal structure of F2-layer parameters. The analysis period covers four months representative of solstitial and equinoctial seasonal periods during solar minimum year of 1987 for geomagnetically quiet-day. We show that month-by-month morphological patterns between vertical E×B drifts and F2-layer parameters range from worst to reasonably good and are largely seasonally dependent. A cross-correlation analysis conducted between equatorial drift and F2-layer characteristics yield statistically significant correlations for equatorial vertical drift and IRI-Bo, IRI-Te and IRI-TEC, whereas little or no acceptable correlation is obtained with observational evidence. Assessment of the association between measured foF2, hmF2 and M(3000)F2 illustrates consistent much more smaller correlation coefficients with no systematic linkage. In general, our research indicates strong departure from simple electrodynamically controlled behavior. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.2298L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.2298L">New aspects of the ionospheric response to the October 2003 superstorms from multiple-satellite observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lei, Jiuhou; Wang, Wenbin; Burns, Alan G.; Yue, Xinan; Dou, Xiankang; Luan, Xiaoli; Solomon, Stanley C.; Liu, Yong C.-M. 2014-03-01 The total electron content (TEC) data measured by the Jason, CHAMP, GRACE, and SAC-C satellites, the in situ electron densities from CHAMP and GRACE, and the vertical E × B drifts from the ROCSAT, have been utilized to examine the ionospheric response to the October 2003 superstorms. The combination of observations from multiple satellites provides a unique global view of ionospheric storm effects, especially over the Pacific Ocean and American regions, which were under sunlit conditions during the main phases of the October 2003 superstorms. The main results of this study are as follows: (1) There were substantial increases in TEC in the daytime at low and middle latitudes during both superstorms. (2) The enhancements were greater during the 30 October superstorm and occurred over a wider range of local times. (3) They also tended to peak at earlier local times during this second event. (4) These TEC enhancement events occurred at the local times when there were enhancements in the upward vertical drift. (5) The strong upward vertical drifts are attributed to penetration electric fields, suggesting that these penetration electric fields played a significant role in the electron density enhancements during these superstorms. Overall, the main contribution of this study is the simultaneous view of the storm time ionospheric response from multiple satellites, and the association of local time differences in ionospheric plasma response with measured vertical drift variations. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active">12</li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active">13</li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25f2103L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25f2103L">Drift turbulence, particle transport, and anomalous dissipation at the reconnecting magnetopause</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Le, A.; Daughton, W.; Ohia, O.; Chen, L.-J.; Liu, Y.-H.; Wang, S.; Nystrom, W. D.; Bird, R. 2018-06-01 Using fully kinetic 3D simulations, the reconnection dynamics of asymmetric current sheets are examined at the Earth's magnetopause. The plasma parameters are selected to model MMS magnetopause diffusion region crossings with guide fields of 0.1, 0.4, and 1 of the reconnecting magnetosheath field. In each case, strong drift-wave fluctuations are observed in the lower-hybrid frequency range at the steep density gradient across the magnetospheric separatrix. These fluctuations give rise to cross-field electron particle transport. In addition, this turbulent mixing leads to significantly enhanced electron parallel heating in comparison to 2D simulations. We study three different methods of quantifying the anomalous dissipation produced by the drift fluctuations, based on spatial averaging, temporal averaging, and temporal averaging followed by integrating along magnetic field lines. A comparison of different methods reveals complications in identifying and measuring the anomalous dissipation. Nevertheless, the anomalous dissipation from short wavelength drift fluctuations appears weak for each case, and the reconnection rates observed in 3D are nearly the same as in 2D models. The 3D simulations feature a number of interesting new features that are consistent with recent MMS observations, including cold beams of magnetosheath electrons that penetrate into the hotter magnetospheric inflow, the related observation of decreasing temperature in regions of increasing total density, and an effective turbulent diffusion coefficient that agrees with predictions from quasi-linear theory. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM31C..06P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM31C..06P">Direct Observations of ULF and Whistler-Mode Chorus Modulation of 500eV EDI Electrons by MMS</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Paulson, K. W.; Argall, M. R.; Ahmadi, N.; Torbert, R. B.; Le Contel, O.; Ergun, R.; Khotyaintsev, Y. V.; Strangeway, R. J.; Magnes, W.; Russell, C. T. 2016-12-01 We present here direct observations of chorus-wave modulated field-aligned 500 eV electrons using the Electron Drift Instrument (EDI) on board the Magnetospheric Multiscale mission. These periods of wave activity were additionally observed to be modulated by Pc5-frequency magnetic perturbations, some of which have been identified as drifting mirror-mode structures. The spacecraft encountered these mirror-mode structures just inside of the duskside magnetopause. Using the high sampling rate provided by EDI in burst sampling mode, we are able to observe the individual count fluctuations of field-aligned electrons in this region up to 512 Hz. We use the multiple look directions of EDI to generate both pitch angle and gyrophase plots of the fluctuating counts. Our observations often show unidirectional flow of these modulated electrons along the background field, and in some cases demonstrate gyrophase bunching in the wave region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...120t4501F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...120t4501F">Tunneling modulation of a quantum-well transistor laser</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Feng, M.; Qiu, J.; Wang, C. Y.; Holonyak, N. 2016-11-01 Different than the Bardeen and Brattain transistor (1947) with the current gain depending on the ratio of the base carrier spontaneous recombination lifetime to the emitter-collector transit time, the Feng and Holonyak transistor laser current gain depends upon the base electron-hole (e-h) stimulated recombination, the base dielectric relaxation transport, and the collector stimulated tunneling. For the n-p-n transistor laser tunneling operation, the electron-hole pairs are generated at the collector junction under the influence of intra-cavity photon-assisted tunneling, with electrons drifting to the collector and holes drifting to the base. The excess charge in the base lowers the emitter junction energy barrier, allowing emitter electron injection into the base and satisfying charge neutrality via base dielectric relaxation transport (˜femtoseconds). The excess electrons near the collector junction undergo stimulated recombination at the base quantum-well or transport to the collector, thus supporting tunneling current amplification and optical modulation of the transistor laser. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26001007','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26001007">Modulated electron cyclotron drift instability in a high-power pulsed magnetron discharge.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Tsikata, Sedina; Minea, Tiberiu 2015-05-08 The electron cyclotron drift instability, implicated in electron heating and anomalous transport, is detected in the plasma of a planar magnetron. Electron density fluctuations associated with the mode are identified via an adapted coherent Thomson scattering diagnostic, under direct current and high-power pulsed magnetron operation. Time-resolved analysis of the mode amplitude reveals that the instability, found at MHz frequencies and millimeter scales, also exhibits a kHz-scale modulation consistent with the observation of larger-scale plasma density nonuniformities, such as the rotating spoke. Sharply collimated axial fluctuations observed at the magnetron axis are consistent with the presence of escaping electrons in a region where the magnetic and electric fields are antiparallel. These results distinguish aspects of magnetron physics from other plasma sources of similar geometry, such as the Hall thruster, and broaden the scope of instabilities which may be considered to dictate magnetron plasma features. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/5028291','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/5028291">New central drift chamber for the MARK II at SLC</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Bartelt, J.E. A new central drift chamber has been constructed for the Mark II detector for use at the new SLAC Linear Collider (SLC). The design of the chamber is based on a multi-sense-wire cell of the jet chamber type. In addition to drift-time measurements, pulse-height measurements from the sense wires provide electron-hadron separation by dE/dx. The chamber has been tested in operation at PEP before its move to the SLC. The design and construction are described, and measurements from the new chamber are presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA41C..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA41C..01A">SAPS and SAID: Differences and implications on modeling</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Anderson, P. C.; Landry, R. G. 2017-12-01 Large subauroral electric fields/ion drifts associated with geomagnetic activity and known as Polarization Jets [Galperin et al., 1973] or subauroral ion drifts (SAID) [Spiro et al., 1978] have been reported by a number of researchers over the years starting in the early 1970s. They are latitudinally narrow ( 1 - 3°), are primarily located between the late afternoon and early morning sectors, are extended several hours in magnetic local time, and have westward drifts that can exceed 5000 m/s. Foster et al., [2002] used Millstone Hill radar data to derive a statistical model of the subauroral ion drifts and coined the term SAPS (Subauroral Polarization Streams) to identify the sometimes broad region of subauroral drifts that the SAID are embedded within. While both are located in the subauroral region and closely associated with ionospheric conductivity and the region 2 field-aligned currents, they are in reality separate phenomena. We investigate this difference, their production mechanisms, and the implications for modeling them. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820016409','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820016409">Electric thruster research</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kaufman, H. R.; Robinson, R. S. 1981-01-01 The multipole discharge chamber of an electrostatic ion thruster is discussed. No reductions in discharge losses were obtained, despite repeated demonstration of anode potentials more positive than the bulk of the discharge plasma. The penalty associated with biased anode operation was reduced as the magnetic integral above the biased anodes was increased. The hollow cathode is discussed. The experimental configuration of the Hall current thruster had a uniform field throughout the ion generation and acceleration regions. To obtain reliable ion generation, it was necessary to reduce the magnetic field strength, to the point where excessive electron backflow was required to establish ion acceleration. The theoretical study of ion acceleration with closed electron drift paths resulted in two classes of solutions. One class has the continuous potential variation in the acceleration region that is normally associated with a Hall current accelerator. The other class has an almost discontinuous potential step near the anode end of the acceleration region. This step includes a significant fraction of the total acceleration potential difference. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E.857F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E.857F">Diagnostics Systems for Permanent Hall Thrusters Development</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ferreira, Jose Leonardo; Soares Ferreira, Ivan; Santos, Jean; Miranda, Rodrigo; Possa, M. Gabriela This work describes the development of Permanent Magnet Hall Effect Plasma Thruster (PHALL) and its diagnostic systems at The Plasma Physics Laboratory of University of Brasilia. The project consists on the construction and characterization of plasma propulsion engines based on the Hall Effect. Electric thrusters have been employed in over 220 successful space missions. Two types stand out: the Hall-Effect Thruster (HET) and the Gridded Ion Engine (GIE). The first, which we deal with in this project, has the advantage of greater simplicity of operation, a smaller weight for the propulsion subsystem and a longer shelf life. It can operate in two configurations: magnetic layer and anode layer, the difference between the two lying in the positioning of the anode inside the plasma channel. A Hall-Effect Thruster-HET is a type of plasma thruster in which the propellant gas is ionized and accelerated by a magneto hydrodynamic effect combined with electrostatic ion acceleration. So the essential operating principle of the HET is that it uses a J x B force and an electrostatic potential to accelerate ions up to high speeds. In a HET, the attractive negative charge is provided by electrons at the open end of the Thruster instead of a grid, as in the case of the electrostatic ion thrusters. A strong radial magnetic field is used to hold the electrons in place, with the combination of the magnetic field and the electrostatic potential force generating a fast circulating electron current, the Hall current, around the axis of the Thruster, mainly composed by drifting electrons in an ion plasma background. Only a slow axial drift towards the anode occurs. The main attractive features of the Hall-Effect Thruster are its simple design and operating principles. Most of the Hall-Effect Thrusters use electromagnet coils to produce the main magnetic field responsible for plasma generation and acceleration. In this paper we present a different new concept, a Permanent Magnet Hall-Effect Thruster (PMHET), developed at the Plasma Physics Laboratory of UnB. The idea of using an array of permanent magnets, instead of an electromagnet, to produce a radial magnetic field inside the cylindrical plasma drift channel of the thruster is very attractive, especially because of the possibility of developing a HET with power consumption low enough to be used in small satellites or medium-size satellites with low on board power. Hall-Effect Thrusters are now a very good option for spacecraft primary propulsion and also for station-keeping of medium and large satellites. This is because of their high specific impulse, efficient use of propellant mass and combined low and precise thrust capabilities, which are related to an economy in terms of propellant mass utilization , longer satellite lifetime and easier spacecraft maneuvering in microgravity environment. The first HETs were developed in the mid 1950’s, and they were first called Closed Drift Thrusters. Today, the successful use of electric thrusters for attitude control and orbit modification on hundreds of satellites shows the advanced stage of development of this technology. In addition to this, after the success of space missions such as Deep Space One and Dawn (NASA), Hayabusa (JAXA) and Smart-1 (ESA), the employment of electric thrusters is also consolidated for the primary propulsion of spacecraft. This success is mainly due to three factors: reliability of this technology; efficiency of propellant utilization, and therefore reduction of the initial mass of the ship; possibility of operation over long time intervals, with practically unlimited cycling and restarts. This thrusting system is designed to be used in satellite attitude control and long term space missions. One of the greatest advantage of this kind of thruster is the production of a steady state magnetic field by permanent magnets providing electron trapping and Hall current generation within a significant decrease on the electric energy supply and thus turning this thruster into a specially good option when it comes to space usage for longer and deep space missions, where solar panels and electric energy storage on batteries is a limiting factor. Two prototype models of permanent magnets Hall Thrusters PHALL I and II were already developed and tested with different permanent magnets systems. From the first studies in Russia (former USSR) soon it became clear that the closed electron drift current (Hall current) inside the source channel was generated by the crossed electric and magnetic (radial) field configuration inside the cylindrical channel. The radial magnetic field action on the circular Hall current inside the channel, combined with the electric field action on the ions, is believed to be the main physical process responsible for plasma acceleration. However a good understanding of the acceleration mechanism and the steady-state plasma dynamics is still missing, and many issues concerning the role of electron transport, plasma fluctuations and instabilities are still open. In this work we describe an integrated diagnostic system used to elucidate these aspects such. Ion energy spectrum, plasma potential profiles, plasma instabilities spectrum, and electron distribution function are some of the plasma diagnosticis needed to undestand the main physics issues on Permanent Magnet Hall Thrusters. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1351235-drift-paths-ions-composing-multiple-nose-spectral-structures-near-inner-edge-plasma-sheet','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1351235-drift-paths-ions-composing-multiple-nose-spectral-structures-near-inner-edge-plasma-sheet">Drift paths of ions composing multiple-nose spectral structures near the inner edge of the plasma sheet</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Ferradas, C. P.; Zhang, J. -C.; Spence, H. E.; ... 2016-11-05 Here in this paper, we present a case study of the H +, He +, and O + multiple-nose structures observed by the Helium, Oxygen, Proton, and Electron instrument on board Van Allen Probe A over one complete orbit on 28 September 2013. Nose structures are observed near the inner edge of the plasma sheet and constitute the signatures of ion drift in the highly dynamic environment of the inner magnetosphere. We find that the multiple noses are intrinsically associated with variations in the solar wind. Backward ion drift path tracings show new details of the drift trajectories of thesemore » ions; i.e., multiple noses are formed by ions with a short drift time from the assumed source location to the inner region and whose trajectories (1) encircle the Earth different number of times or (2) encircle the Earth equal number of times but with different drift time, before reaching the observation site.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1351235','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1351235">Drift paths of ions composing multiple-nose spectral structures near the inner edge of the plasma sheet</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ferradas, C. P.; Zhang, J. -C.; Spence, H. E. Here in this paper, we present a case study of the H +, He +, and O + multiple-nose structures observed by the Helium, Oxygen, Proton, and Electron instrument on board Van Allen Probe A over one complete orbit on 28 September 2013. Nose structures are observed near the inner edge of the plasma sheet and constitute the signatures of ion drift in the highly dynamic environment of the inner magnetosphere. We find that the multiple noses are intrinsically associated with variations in the solar wind. Backward ion drift path tracings show new details of the drift trajectories of thesemore » ions; i.e., multiple noses are formed by ions with a short drift time from the assumed source location to the inner region and whose trajectories (1) encircle the Earth different number of times or (2) encircle the Earth equal number of times but with different drift time, before reaching the observation site.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/1394980-understanding-mechanisms-radiation-belt-dropouts-observed-van-allen-probes','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1394980-understanding-mechanisms-radiation-belt-dropouts-observed-van-allen-probes">Understanding the mechanisms of radiation belt dropouts observed by Van Allen Probes</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Xiang, Zheng; Tu, Weichao; Li, Xinlin To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and themore » μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Here, our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* < 4, while EMIC waves can efficiently scatter electrons at L* > 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. Finally, the evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.9858X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.9858X">Understanding the Mechanisms of Radiation Belt Dropouts Observed by Van Allen Probes</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Xiang, Zheng; Tu, Weichao; Li, Xinlin; Ni, Binbin; Morley, S. K.; Baker, D. N. 2017-10-01 To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and the μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* < 4, while EMIC waves can efficiently scatter electrons at L* > 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. The evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1394980-understanding-mechanisms-radiation-belt-dropouts-observed-van-allen-probes','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1394980-understanding-mechanisms-radiation-belt-dropouts-observed-van-allen-probes">Understanding the mechanisms of radiation belt dropouts observed by Van Allen Probes</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Xiang, Zheng; Tu, Weichao; Li, Xinlin; ... 2017-08-30 To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and themore » μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Here, our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* < 4, while EMIC waves can efficiently scatter electrons at L* > 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. Finally, the evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900065487&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900065487&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddropout">Global magnetic anomaly and aurora of Neptune</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cheng, Andrew F. 1990-01-01 The large offset and tilt of Neptune's dipole magnetic field combine to create a global magnetic anomaly, analogous to but much more important than earth's South Atlantic Anomaly. Energetic particle precipitation loss within the Neptune anomaly creates 'atmospheric drift shadows' within which particle fluxes are greatly reduced. The energetic particle dropout observed by Voyager near closest approach occurred near the predicted times when Voyager passed within the atmospheric drift shadow. Extremely soft, structured bursts of ions and electrons within the drift shadow may result from plasma wave-induced pitch angle scattering of trapped particles confined near the magnetic equator. The dropout does not necessarily imply that Voyager passed through an earth-like discrete auroral zone, as earlier reported. The ion and electron fluxes observed within the dropout period correspond to particles that must precipitate to Neptune's atmosphere within the anomaly region. This anomaly precipitation can account for a major portion of the ultraviolet emissions previously identified as Neptune aurora. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SPIE.8196E..22X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SPIE.8196E..22X">Design of motion adjusting system for space camera based on ultrasonic motor</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Xu, Kai; Jin, Guang; Gu, Song; Yan, Yong; Sun, Zhiyuan 2011-08-01 Drift angle is a transverse intersection angle of vector of image motion of the space camera. Adjusting the angle could reduce the influence on image quality. Ultrasonic motor (USM) is a new type of actuator using ultrasonic wave stimulated by piezoelectric ceramics. They have many advantages in comparison with conventional electromagnetic motors. In this paper, some improvement was designed for control system of drift adjusting mechanism. Based on ultrasonic motor T-60 was designed the drift adjusting system, which is composed of the drift adjusting mechanical frame, the ultrasonic motor, the driver of Ultrasonic Motor, the photoelectric encoder and the drift adjusting controller. The TMS320F28335 DSP was adopted as the calculation and control processor, photoelectric encoder was used as sensor of position closed loop system and the voltage driving circuit designed as generator of ultrasonic wave. It was built the mathematic model of drive circuit of the ultrasonic motor T-60 using matlab modules. In order to verify the validity of the drift adjusting system, was introduced the source of the disturbance, and made simulation analysis. It designed the control systems of motor drive for drift adjusting system with the improved PID control. The drift angle adjusting system has such advantages as the small space, simple configuration, high position control precision, fine repeatability, self locking property and low powers. It showed that the system could accomplish the mission of drift angle adjusting excellent. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950029587&hterms=cell+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcell%2Bseparation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950029587&hterms=cell+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcell%2Bseparation">Particle-in-cell simulations of the critical ionization velocity effect in finite size clouds</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moghaddam-Taaheri, E.; Lu, G.; Goertz, C. K.; Nishikawa, K. - I. 1994-01-01 The critical ionization velocity (CIV) mechanism in a finite size cloud is studied with a series of electrostatic particle-in-cell simulations. It is observed that an initial seed ionization, produced by non-CIV mechanisms, generates a cross-field ion beam which excites a modified beam-plasma instability (MBPI) with frequency in the range of the lower hybrid frequency. The excited waves accelerate electrons along the magnetic field up to the ion drift energy that exceeds the ionization energy of the neutral atoms. The heated electrons in turn enhance the ion beam by electron-neutral impact ionization, which establishes a positive feedback loop in maintaining the CIV process. It is also found that the efficiency of the CIV mechanism depends on the finite size of the gas cloud in the following ways: (1) Along the ambient magnetic field the finite size of the cloud, L (sub parallel), restricts the growth of the fastest growing mode, with a wavelength lambda (sub m parallel), of the MBPI. The parallel electron heating at wave saturation scales approximately as (L (sub parallel)/lambda (sub m parallel)) (exp 1/2); (2) Momentum coupling between the cloud and the ambient plasma via the Alfven waves occurs as a result of the finite size of the cloud in the direction perpendicular to both the ambient magnetic field and the neutral drift. This reduces exponentially with time the relative drift between the ambient plasma and the neutrals. The timescale is inversely proportional to the Alfven velocity. (3) The transvers e charge separation field across the cloud was found to result in the modulation of the beam velocity which reduces the parallel heating of electrons and increases the transverse acceleration of electrons. (4) Some energetic electrons are lost from the cloud along the magnetic field at a rate characterized by the acoustic velocity, instead of the electron thermal velocity. The loss of energetic electrons from the cloud seems to be larger in the direction of plasma drift relative to the neutrals, where the loss rate is characterized by the neutral drift velocity. It is also shown that a factor of 4 increase in the ambient plasma density, increases the CIV ionization yield by almost 2 orders of magnitude at the end of a typical run. It is concluded that a larger ambient plasma density can result in a larger CIV yield because of (1) larger seed ion production by non-CIV mechanisms, (2) smaller Alfven velocity and hence weak momentum coupling, and (3) smaller ratio of the ion beam density to the ambient ion density, and therefore a weaker modulation of the beam velocity. The simulation results are used to interpret various chemical release experiments in space. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TESS....140320K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TESS....140320K">Measurements Verifying the Optics of the Electron Drift Instrument</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kooi, Vanessa; Kletzing, Craig; Bounds, Scott; Sigsbee, Kristine M. 2015-04-01 Magnetic reconnection is the process of breaking and reconnecting of opposing magnetic field lines, and is often associated with tremendous energy transfer. The energy transferred by reconnection directly affects people through its influence on geospace weather and technological systems - such as telecommunication networks, GPS, and power grids. However, the mechanisms that cause magnetic reconnection are not well understood. The Magnetospheric Multi-Scale Mission (MMS) will use four spacecraft in a pyramid formation to make three-dimensional measurements of the structures in magnetic reconnection occurring in the Earth's magnetosphere.The spacecraft will repeatedly sample these regions for a prolonged period of time to gather data in more detail than has been previously possible. MMS is scheduled to be launched in March of 2015. The Electron Drift Instrument (EDI) will be used on MMS to measure the electric fields associated with magnetic reconnection. The EDI is a device used on spacecraft to measure electric fields by emitting an electron beam and measuring the E x B drift of the returning electrons after one gyration. This paper concentrates on measurements of the EDI’s optics system. The testing process includes measuring the optics response to a uni-directional electron beam. These measurements are used to verify the response of the EDI's optics and to allow for the optimization of the desired optics state. The measurements agree well with simulations and we are confident in the performance of the EDI instrument. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..93s5315A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..93s5315A">Current-driven plasmonic boom instability in three-dimensional gated periodic ballistic nanostructures</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Aizin, G. R.; Mikalopas, J.; Shur, M. 2016-05-01 An alternative approach of using a distributed transmission line analogy for solving transport equations for ballistic nanostructures is applied for solving the three-dimensional problem of electron transport in gated ballistic nanostructures with periodically changing width. The structures with varying width allow for modulation of the electron drift velocity while keeping the plasma velocity constant. We predict that in such structures biased by a constant current, a periodic modulation of the electron drift velocity due to the varying width results in the instability of the plasma waves if the electron drift velocity to plasma wave velocity ratio changes from below to above unity. The physics of such instability is similar to that of the sonic boom, but, in the periodically modulated structures, this analog of the sonic boom is repeated many times leading to a larger increment of the instability. The constant plasma velocity in the sections of different width leads to resonant excitation of the unstable plasma modes with varying bias current. This effect (that we refer to as the superplasmonic boom condition) results in a strong enhancement of the instability. The predicted instability involves the oscillating dipole charge carried by the plasma waves. The plasmons can be efficiently coupled to the terahertz electromagnetic radiation due to the periodic geometry of the gated structure. Our estimates show that the analyzed instability should enable powerful tunable terahertz electronic sources. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22303598-short-wavelength-limits-current-shot-noise-suppression','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22303598-short-wavelength-limits-current-shot-noise-suppression">Short wavelength limits of current shot noise suppression</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Nause, Ariel, E-mail: arielnau@post.tau.ac.il; Dyunin, Egor; Gover, Avraham Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasmamore » wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23262895','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23262895">Enhanced 10 Gb/s operations of directly modulated reflective semiconductor optical amplifiers without electronic equalization.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Presi, M; Chiuchiarelli, A; Corsini, R; Choudury, P; Bottoni, F; Giorgi, L; Ciaramella, E 2012-12-10 We report enhanced 10 Gb/s operation of directly modulated bandwidth-limited reflective semiconductor optical amplifiers. By using a single suitable arrayed waveguide grating we achieve simultaneously WDM demultiplexing and optical equalization. Compared to previous approaches, the proposed system results significantly more tolerant to seeding wavelength drifts. This removes the need for wavelength lockers, additional electronic equalization or complex digital signal processing. Uniform C-band operations are obtained experimentally with < 2 dB power penalty within a wavelength drift of 10 GHz (which doubles the ITU-T standard recommendations). </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active">13</li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active">14</li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy..tmp.2387D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy..tmp.2387D">Ocean circulation drifts in multi-millennial climate simulations: the role of salinity corrections and climate feedbacks</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dentith, Jennifer E.; Ivanovic, Ruza F.; Gregoire, Lauren J.; Tindall, Julia C.; Smith, Robin S. 2018-05-01 Low-resolution, complex general circulation models (GCMs) are valuable tools for studying the Earth system on multi-millennial timescales. However, slowly evolving salinity drifts can cause large shifts in climatic and oceanic regimes over thousands of years. We test two different schemes for neutralising unforced salinity drifts in the FAMOUS GCM: surface flux correction and volumetric flux correction. Although both methods successfully maintain a steady global mean salinity, local drifts and subsequent feedbacks promote cooling (≈ 4 °C over 6000 years) and freshening (≈ 2 psu over 6000 years) in the North Atlantic Ocean, and gradual warming (≈ 0.2 °C per millennium) and salinification (≈ 0.15 psu per millennium) in the North Pacific Ocean. Changes in the surface density in these regions affect the meridional overturning circulation (MOC), such that, after several millennia, the Atlantic MOC (AMOC) is in a collapsed state, and there is a strong, deep Pacific MOC (PMOC). Furthermore, the AMOC exhibits a period of metastability, which is only identifiable with run lengths in excess of 1500 years. We also compare simulations with two different land surface schemes, demonstrating that small biases in the surface climate may cause regional salinity drifts and significant shifts in the MOC (weakening of the AMOC and the initiation then invigoration of PMOC), even when the global hydrological cycle has been forcibly closed. Although there is no specific precursor to the simulated AMOC collapse, the northwest North Pacific and northeast North Atlantic are important areas that should be closely monitored for trends arising from such biases. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1259287-wave-driven-butterfly-distribution-van-allen-belt-relativistic-electrons','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1259287-wave-driven-butterfly-distribution-van-allen-belt-relativistic-electrons">Wave-driven butterfly distribution of Van Allen belt relativistic electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; ... 2015-10-05 Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth’s magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28more » June 2013 geomagnetic storm. In conclusion, simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. Finally, the current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1259287','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1259287">Wave-driven butterfly distribution of Van Allen belt relativistic electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Xiao, Fuliang; Yang, Chang; Su, Zhenpeng Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth’s magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28more » June 2013 geomagnetic storm. In conclusion, simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. Finally, the current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25b2305R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25b2305R">Three-dimensional simulations of plasma turbulence in the RFX-mod scrape-off layer and comparison with experimental measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Riva, Fabio; Vianello, Nicola; Spolaore, Monica; Ricci, Paolo; Cavazzana, Roberto; Marrelli, Lionello; Spagnolo, Silvia 2018-02-01 The tokamak scrape-off layer (SOL) plasma dynamics is investigated in a circular limiter configuration with a low edge safety factor. Focusing on the experimental parameters of two ohmic tokamak inner-wall limited plasma discharges in RFX-mod [Sonato et al., Fusion Eng. Des. 74, 97 (2005)], nonlinear SOL plasma simulations are performed with the GBS code [Ricci et al., Plasma Phys. Controlled Fusion 54, 124047 (2012)]. The numerical results are compared with the experimental measurements, assessing the reliability of the GBS model in describing the RFX-mod SOL plasma dynamics. It is found that the simulations are able to quantitatively reproduce the RFX-mod experimental measurements of the electron plasma density, electron temperature, and ion saturation current density (jsat) equilibrium profiles. Moreover, there are indications that the turbulent transport is driven by the same instability in the simulations and in the experiment, with coherent structures having similar statistical properties. On the other hand, it is found that the simulation results are not able to correctly reproduce the floating potential equilibrium profile and the jsat fluctuation level. It is likely that these discrepancies are, at least in part, related to simulating only the tokamak SOL region, without including the plasma dynamics inside the last close flux surface, and to the limits of applicability of the drift approximation. The turbulence drive is then identified from the nonlinear simulations and with the linear theory. It results that the inertial drift wave is the instability driving most of the turbulent transport in the considered discharges. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990QuEle..20..570V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990QuEle..20..570V">FIBER AND INTEGRATED OPTICS. OTHER TOPICS IN QUANTUM ELECTRONICS: Modulation method for reducing long-term drift of the emission frequency of an He-Ne laser (λ = 0.63 μm) generating two orthogonally polarized electromagnetic waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vitushkin, L. F.; Zakharenko, Yu G.; Smirnov, M. Z. 1990-05-01 Theoretical and experimental investigations were made of the principal physical factors responsible for a long-term drift of the frequency of the radiation generated in a stabilized two-frequency He-Ne laser with internal mirrors, emitting two orthogonally polarized electromagnetic waves. When zero difference between the intensities was controlled by a modulation method and the frequency was set before each measurement, a long-term (over a period of a year) frequency drift did not exceed 10 - 8, but in the absence of such control the drift could reach 5 × 10 - 8. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMNG14A..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMNG14A..02P">Drift waves control using emissive cathodes in the laboratory</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Plihon, N.; Desangles, V.; De Giorgio, E.; Bousselin, G.; Marino, R.; Pustelnik, N.; Poye, A. 2017-12-01 Low frequency plasma fluctuations are known to be the cause of strong transport perpendicular to magnetic guiding field line. These low frequency drift waves have been studied in linear devices in the laboratory over the last two decades. Their excitation or mitigation have been addressed using different drives, such as ring biasing or electromagnetic low frequency fields. Here we present an experimental characterization of the behavior of drift waves when the profile of the background plasma rotation is controlled using hot emissive cathodes. We show that electron emission from the cathodes modify the plasma potential, which in turn controls the rotation profile. Mitigation or enhancement of drift waves (on the amplitude or azimuthal mode number) is observed depending on the plasma rotation profile. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24j2516B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24j2516B">A conservative scheme of drift kinetic electrons for gyrokinetic simulation of kinetic-MHD processes in toroidal plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bao, J.; Liu, D.; Lin, Z. 2017-10-01 A conservative scheme of drift kinetic electrons for gyrokinetic simulations of kinetic-magnetohydrodynamic processes in toroidal plasmas has been formulated and verified. Both vector potential and electron perturbed distribution function are decomposed into adiabatic part with analytic solution and non-adiabatic part solved numerically. The adiabatic parallel electric field is solved directly from the electron adiabatic response, resulting in a high degree of accuracy. The consistency between electrostatic potential and parallel vector potential is enforced by using the electron continuity equation. Since particles are only used to calculate the non-adiabatic response, which is used to calculate the non-adiabatic vector potential through Ohm's law, the conservative scheme minimizes the electron particle noise and mitigates the cancellation problem. Linear dispersion relations of the kinetic Alfvén wave and the collisionless tearing mode in cylindrical geometry have been verified in gyrokinetic toroidal code simulations, which show that the perpendicular grid size can be larger than the electron collisionless skin depth when the mode wavelength is longer than the electron skin depth. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998APS..DPPS8I104C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998APS..DPPS8I104C">Diagnostics of Plasma Propulsion Devices</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cappelli, Mark A. 1998-11-01 Plasma rockets are rapidly emerging as critical technologies in future space flight. These devices take on various forms, ranging from electro-thermal to electromagnetic accelerators, generally categorized by the method in which electrical energy is converted to thrust. As is the case in many plasma devices, non-intrusive optical (emission, or laser-based) diagnostics is an essential element in the characterization of these plasma sources, as access to the discharges in these plasma engines is often limited. Furthermore, laser-based diagnostics offer additional benefits, including improved spatial resolution, and can provide state-specific measurements of species densities, velocities and energy distributions. In recent years, we have developed and applied a variety of emission and laser-based diagnostics strategies to the characterization of arcjet plasma and closed-drift xenon Hall plasma accelerators. Both of these types of plasma propulsion devices are of immediate interest to the space propulsion community, and are under varying stages of development. Arcjet thrusters have unique properties, with strong plasma density, temperature and velocity gradients, which enhance the coupling between the gasdynamic and plasma physics. Closed-drift Hall plasma thrusters are low density electrostatic devices that are inherently turbulent, and exhibit varying degrees of anomalous cross-field electron transport. Our most extensive, collective effort has been to apply laser-induced fluorescence, Doppler-free laser absorption, and Raman scattering to the characterization of hydrogen and helium arcjet flows. Detailed measurements of velocity, temperatures, and electron densities are compared to the results of magneto-hydrodynamic flowfield simulations. The results show that while the simulations capture many aspects of the flow, there are still some unresolved discrepancies. The database established for Hall thrusters is less extensive, as the laser absorption spectroscopy of xenon is somewhat more complicated due to the hyperfine and isotopic structure of electronic transitions. With an understanding of the spectroscopic absorption lineshape for two select transitions in neutral and ionized xenon, we have successfully mapped out the neutral and singly ionized xenon velocities in the acceleration zone of Hall thrusters. These results indicate that the acceleration zone in a short-channel thruster is outside of the device, consistent with the measurements of plasma potential using more conventional Langmuir electrostatic probes. The spectroscopic data has also been used to identify limitations in ground-test facilities. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24641915','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24641915">Improving signal to noise in labeled biological specimens using energy-filtered TEM of sections with a drift correction strategy and a direct detection device.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Ramachandra, Ranjan; Bouwer, James C; Mackey, Mason R; Bushong, Eric; Peltier, Steven T; Xuong, Nguyen-Huu; Ellisman, Mark H 2014-06-01 Energy filtered transmission electron microscopy techniques are regularly used to build elemental maps of spatially distributed nanoparticles in materials and biological specimens. When working with thick biological sections, electron energy loss spectroscopy techniques involving core-loss electrons often require exposures exceeding several minutes to provide sufficient signal to noise. Image quality with these long exposures is often compromised by specimen drift, which results in blurring and reduced resolution. To mitigate drift artifacts, a series of short exposure images can be acquired, aligned, and merged to form a single image. For samples where the target elements have extremely low signal yields, the use of charge coupled device (CCD)-based detectors for this purpose can be problematic. At short acquisition times, the images produced by CCDs can be noisy and may contain fixed pattern artifacts that impact subsequent correlative alignment. Here we report on the use of direct electron detection devices (DDD's) to increase the signal to noise as compared with CCD's. A 3× improvement in signal is reported with a DDD versus a comparably formatted CCD, with equivalent dose on each detector. With the fast rolling-readout design of the DDD, the duty cycle provides a major benefit, as there is no dead time between successive frames. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22403503-brownian-motion-massive-skyrmions-magnetic-thin-films','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22403503-brownian-motion-massive-skyrmions-magnetic-thin-films">Brownian motion of massive skyrmions in magnetic thin films</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com; Núñez, Álvaro S., E-mail: alnunez@dfi.uchile.cl 2014-12-15 We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele’s equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By using this ansatz it is found that the skyrmion mass tensor is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal andmore » transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1346872-negative-viscosity-from-negative-compressibility-axial-flow-shear-stiffness-straight-magnetic-field','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1346872-negative-viscosity-from-negative-compressibility-axial-flow-shear-stiffness-straight-magnetic-field">Negative viscosity from negative compressibility and axial flow shear stiffness in a straight magnetic field</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Li, J. C.; Diamond, P. H. 2017-03-23 Here, negative compressibility ITG turbulence in a linear plasma device (CSDX) can induce a negative viscosity increment. However, even with this negative increment, we show that the total axial viscosity remains positive definite, i.e. no intrinsic axial flow can be generated by pure ITG turbulence in a straight magnetic field. This differs from the case of electron drift wave (EDW) turbulence, where the total viscosity can turn negative, at least transiently. When the flow gradient is steepened by any drive mechanism, so that the parallel shear flow instability (PSFI) exceeds the ITG drive, the flow profile saturates at a level close to the value above which PSFI becomes dominant. This saturated flow gradient exceeds the PSFI linear threshold, and grows withmore » $$\ </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000SuMi...27..545E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000SuMi...27..545E">Ionic channels: natural nanotubes described by the drift diffusion equations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Eisenberg, Bob 2000-05-01 Ionic channels are a large class of proteins with holes down their middle that control a wide range of cellular functions important in health and disease. Ionic channels can be analysed using a combination of the Poisson and drift diffusion equations familiar from computational electronics because their behavior is dominated by the electrical properties of their simple structure. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23683209','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23683209">Numerical verification of bounce-harmonic resonances in neoclassical toroidal viscosity for tokamaks.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Kim, Kimin; Park, Jong-Kyu; Boozer, Allen H 2013-05-03 This Letter presents the first numerical verification for the bounce-harmonic (BH) resonance phenomena of the neoclassical transport in a tokamak perturbed by nonaxisymmetric magnetic fields. The BH resonances were predicted by analytic theories of neoclassical toroidal viscosity (NTV), as the parallel and perpendicular drift motions can be resonant and result in a great enhancement of the radial momentum transport. A new drift-kinetic δf guiding-center particle code, POCA, clearly verified that the perpendicular drift motions can reduce the transport by phase-mixing, but in the BH resonances the motions can form closed orbits and particles radially drift out fast. The POCA calculations on resulting NTV torque are largely consistent with analytic calculations, and show that the BH resonances can easily dominate the NTV torque when a plasma rotates in the perturbed tokamak and therefore, is a critical physics for predicting the rotation and stability in the International Thermonuclear Experimental Reactor. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSM32A..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSM32A..02H">Energization of Radiation Belt Electrons by High and Low Azimuthal Mode Number Poloidal Mode ULF Waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hudson, M. K.; Brito, T.; Elkington, S. R.; Kress, B. T.; Liang, Y. 2011-12-01 CME-shock and CIR-driven geomagnetic storms are characterized by enhanced ULF wave activity in the magnetosphere. This enhanced ULF wave power produces both coherent and diffusive transport and energization, as well as pitch angle modification of radiation belt electrons in drift resonance with azimuthally propagating ULF waves. Recent observations of two CME-driven storms1,2 have suggested that poloidal mode waves with both low and high azimuthal mode number may be efficient at accelerating radiation belt electrons. We extend up to m = 50 the analysis of Ozeke and Mann3 who examined drift resonance for poloidal modes up to m = 40. We calculate radial diffusion coefficients for source population electrons in the 50 -500 keV range, and continued resonance with lower m-numbers at higher energies for ULF waves in the Pc 5, 0.4 - 10 mHz range. We use an analytic model for ULF waves superimposed on a compressed dipole, developed for equatorial plane studies by Elkington et al.4 and extended to 3D by Perry et al.4 Assuming a power spectrum which varies as ω-2, consistent with earlier observations, we find greater efficiency for radial transport and acceleration at lower m number where there is greater power for drift resonance at a given frequency. This assumption is consistent with 3D global MHD simulations using the Lyon-Fedder-Mobarry code which we have carried out for realistic solar wind driving conditions during storms. Coherent interaction with ULF waves can also occur at a rate which exceeds nominal radial diffusion estimates but is slower than prompt injection on a drift time scale. Depending on initial electron drift phase, some electrons are accelerated due to the westward azimuthal electric field Eφ, while others are decelerated by eastward Eφ, decreasing their pitch angle. A subset of trapped electrons are seen to precipitate to the atmosphere in 3D LFM simulations, showing modulation at the coherent poloidal mode ULF wave frequency in both simulations and MINIS balloon observations for the January 21, 2005 CME-driven storm. Thus Pc 5 poloidal mode ULF waves cause competing increase and decrease in relativistic electron flux. The relative efficiencies of both coherent and diffusive processes will be examined. 1Zong et al., JGR, doi:10.1029/2009JA014393, 2009. 2Tan et al., JGR, doi:10.1029/2010JA016226, 2011. 3Ozeke and Mann, JGR, doi:10.1029/2007JA012468, 2008. 4Elkington et al., doi:10.1029/2001JA009202, 2003, 2003. 5Perry et al., doi:10.1029/2004JA010760, 2005. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://eric.ed.gov/?q=test+AND+locomotor&pg=4&id=EJ734721','ERIC'); return false;" href="https://eric.ed.gov/?q=test+AND+locomotor&pg=4&id=EJ734721">Self-Motion Perception during Locomotor Recalibration: More than Meets the Eye</a> <a target="_blank" rel="noopener noreferrer" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a> Durgin, Frank H.; Pelah, Adar; Fox, Laura F.; Lewis, Jed; Kane, Rachel; Walley, Katherine A. 2005-01-01 Do locomotor after effects depend specifically on visual feedback? In 7 experiments, 116 college students were tested, with closed eyes, at stationary running or at walking to a previewed target after adaptation, with closed eyes, to treadmill locomotion. Subjects showed faster inadvertent drift during stationary running and increased distance… </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940009320','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940009320">Stormtime transport of ring current and radiation belt ions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chen, Margaret W.; Schulz, Michael; Lyons, L. R.; Gorney, David J. 1993-01-01 This is an investigation of stormtime particle transport that leads to formation of the ring current. Our method is to trace the guiding-center motion of representative ions (having selected first adiabatic invariants mu) in response to model substorm-associated impulses in the convection electric field. We compare our simulation results qualitatively with existing analytically tractable idealizations of particle transport (direct convective access and radial diffusion) in order to assess the limits of validity of these approximations. For mu approximately less than 10 MeV/G (E approximately less than 10 keV at L equivalent to 3) the ion drift period on the final (ring-current) drift shell of interest (L equivalent to 3) exceeds the duration of the main phase of our model storm, and we find that the transport of ions to this drift shell is appropriately idealized as direct convective access, typically from open drift paths. Ion transport to a final closed drift path from an open (plasma-sheet) drift trajectory is possible for those portions of that drift path that lie outside the mean stormtime separatrix between closed and open drift trajectories, For mu approximately 10-25 MeV/G (110 keV approximately less than E approximately less than 280 keV at L equivalent to 3) the drift period at L equivalent to 3 is comparable to the postulated 3-hr duration of the storm, and the mode of transport is transitional between direct convective access and transport that resembles radial diffusion. (This particle population is transitional between the ring current and radiation belt). For mu approximately greater than 25 MeV/G (radiation-belt ions having E approximately greater than 280 keV at L equivalent to 3) the ion drift period is considerably shorter than the main phase of a typical storm, and ions gain access to the ring-current region essentially via radial diffusion. By computing the mean and mean-square cumulative changes in 1/L among (in this case) 12 representative ions equally spaced in drift time around the steady-state drift shell of interest (L equivalent to 3), we have estimated (from both our forward and our time-reversed simulations) the time-integrated radial-diffusion coefficients D(sup sim)(sub LL) for particles having selected values of mu approximately greater than 15 MeV/G. The results agree surprisingly well with the predictions (D(sup ql)(sub LL)) of quasilinear radial diffusion theory, despite the rather brief duration (approximately 3 hrs) of our model storm and despite the extreme variability (with frequency) of the spectral-density function that characterizes the applied electric field during our model storm. As expected, the values of D(sup sim)(sub LL) deduced (respectively) from our forward and time-reversed simulations agree even better with each other and with D(sup sim)(sub LL) when the impulse amplitudes which characterize the individual substorms of our model storm are systematically reduced. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930071342&hterms=horses&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhorses','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930071342&hterms=horses&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhorses">Dynamics Explorer measurements of particles, fields, and plasma drifts over a horse-collar auroral pattern</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sharber, J. R.; Hones, E. W., Jr.; Heelis, R. A.; Craven, J. D.; Frank, L. A.; Maynard, N. C.; Slavin, J. A.; Birn, J. 1992-01-01 As shown from ground-based measurements and satellite-borne imagers, one type of global auroral pattern characteristic of quiet (usually northward IMF) intervals is that of a contracted but thickened emission region of a pattern referred to as 'horse-collar' aurora (Hones et al., 1989). In this report we use the Dynamics Explorer data set to examine a case in which this horse-collar pattern was observed by the DE-1 auroral imager, while at the same time DE-2, at lower altitude, measured precipitating particles, electric and magnetic fields, and plasma drifts. Our analysis shows that, in general, there is close agreement between the optical signatures and the particle precipitation patterns. In many instances, over scales ranging from tens to a few hundred kilometers, electron precipitation features and upward field-aligned currents are observed at locations where the plasma flow gradients indicate negative V-average x E. The particle, plasma, and field measurements made along the satellite track and the 2D perspective of the imager provide a means of determining the configuration of convective flows in the high-latitude ionosphere during this interval of northward IMF. Recent mapping studies are used to relate the low-altitude observations to possible magnetospheric source regions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.4181H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.4181H">Effects of Geomagnetic Storms on the Postsunset Vertical Plasma Drift in the Equatorial Ionosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Huang, Chao-Song 2018-05-01 It has been observed that geomagnetic storms cause suppression of the occurrence of equatorial spread F or plasma bubbles in the evening sector. In this study, we use ion drift data measured by the Communication/Navigation Outage Forecasting System satellite over 6 years (2008-2014) to derive the dependence of the vertical ion drift at the prereversal enhancement peak on the strength of magnetic storms (the Dst index). It is found that the average vertical ion drift does not change much for Dst in the range between 0 and -60 nT but decreases approximately linearly with the increasing magnitude of Dst for Dst < -60 nT. The net decrease in the average vertical ion drift is 30 m/s when Dst changes from -60 to -90 nT. This result is derived when the ion drift data during the storm main phase are excluded, so the decrease of the vertical ion drift is caused by storm time disturbance dynamo. A possible interpretation of this phenomenon is that geomagnetic activity must be strong enough (e.g., Dst < -60 nT) so disturbance winds can reach the equatorial region and change plasma drifts there. The storm time disturbance dynamo becomes dominant in the equatorial ionospheric dynamics near the end of the storm main phase, 4.7 hr after the storm onset. The postsunset vertical ion drift is significantly decreased during the early stage of the storm recovery phase but becomes almost fully recovered when Dst increases close to -60 nT. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4712810','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4712810">Fishing for drifts: detecting buoyancy changes of a top marine predator using a step-wise filtering method</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Gordine, Samantha Alex; Fedak, Michael; Boehme, Lars 2015-01-01 ABSTRACT In southern elephant seals (Mirounga leonina), fasting- and foraging-related fluctuations in body composition are reflected by buoyancy changes. Such buoyancy changes can be monitored by measuring changes in the rate at which a seal drifts passively through the water column, i.e. when all active swimming motion ceases. Here, we present an improved knowledge-based method for detecting buoyancy changes from compressed and abstracted dive profiles received through telemetry. By step-wise filtering of the dive data, the developed algorithm identifies fragments of dives that correspond to times when animals drift. In the dive records of 11 southern elephant seals from South Georgia, this filtering method identified 0.8–2.2% of all dives as drift dives, indicating large individual variation in drift diving behaviour. The obtained drift rate time series exhibit that, at the beginning of each migration, all individuals were strongly negatively buoyant. Over the following 75–150 days, the buoyancy of all individuals peaked close to or at neutral buoyancy, indicative of a seal's foraging success. Independent verification with visually inspected detailed high-resolution dive data confirmed that this method is capable of reliably detecting buoyancy changes in the dive records of drift diving species using abstracted data. This also affirms that abstracted dive profiles convey the geometric shape of drift dives in sufficient detail for them to be identified. Further, it suggests that, using this step-wise filtering method, buoyancy changes could be detected even in old datasets with compressed dive information, for which conventional drift dive classification previously failed. PMID:26486362 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1394293-sol-effects-pedestal-structure-diii-discharges','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1394293-sol-effects-pedestal-structure-diii-discharges">SOL effects on the pedestal structure in DIII-D discharges</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Sontag, Aaron C.; Chen, Xi; Canik, John; ... 2017-05-24 SOLPS analysis explains the differences in pedestal structure associated with different ion ∇B drift directions in DIII-D. Core transport models predict that fusion power scales roughly as the square of the pressure at the top of the pedestal, so understanding the effects that determine pedestal structure in steady-state operational scenarios is important to projecting scenarios developed in DIII-D to ITER and other devices. Both experiments and modeling indicate that scrape off layer (SOL) conditions are important in optimizing the pedestal structure for high-beta steady-state scenarios. The SOLPS code is used to provide interpretive analysis of the pedestal and SOL tomore » examine the nature of flows and fueling on the pedestal structure including the effects of drifts in the fluid model. This analysis shows that flows driven by the ion ∇B drift are outward when this drift is toward the x-point in a single-null divertor configuration (favorable ∇B direction for reduced H-mode power threshold), and inward when the drift is away from the x-point (unfavorable ∇B direction). It is hypothesized that these flows decrease the density gradient in the pedestal in the favorable direction, thereby stabilizing the kinetic ballooning mode (KBM) and increasing the pedestal width. Comparisons of pedestal structures in similarly shaped DIII-D steady-state plasmas confirm this change, showing increased density pedestal width and lower peak density and lower separatrix density with the favorable drift direction. The pedestal temperature is higher in the lower density case, resulting in an increased pedestal pressure, which indicates that the increased particle flux does not significantly degrade energy confinement. Modeling of cases with constant ∇B drift direction but changing between the more open lower divertor and more closed upper divertor show that there is increased fueling inside the pedestal with the more open geometry. As a result, the pedestal fueling rate for both attached and detached cases is always lower with more closed divertor geometry than in any cases with more open geometry.« less </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active">14</li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active">15</li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1394293','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1394293">SOL effects on the pedestal structure in DIII-D discharges</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Sontag, Aaron C.; Chen, Xi; Canik, John SOLPS analysis explains the differences in pedestal structure associated with different ion ∇B drift directions in DIII-D. Core transport models predict that fusion power scales roughly as the square of the pressure at the top of the pedestal, so understanding the effects that determine pedestal structure in steady-state operational scenarios is important to projecting scenarios developed in DIII-D to ITER and other devices. Both experiments and modeling indicate that scrape off layer (SOL) conditions are important in optimizing the pedestal structure for high-beta steady-state scenarios. The SOLPS code is used to provide interpretive analysis of the pedestal and SOL tomore » examine the nature of flows and fueling on the pedestal structure including the effects of drifts in the fluid model. This analysis shows that flows driven by the ion ∇B drift are outward when this drift is toward the x-point in a single-null divertor configuration (favorable ∇B direction for reduced H-mode power threshold), and inward when the drift is away from the x-point (unfavorable ∇B direction). It is hypothesized that these flows decrease the density gradient in the pedestal in the favorable direction, thereby stabilizing the kinetic ballooning mode (KBM) and increasing the pedestal width. Comparisons of pedestal structures in similarly shaped DIII-D steady-state plasmas confirm this change, showing increased density pedestal width and lower peak density and lower separatrix density with the favorable drift direction. The pedestal temperature is higher in the lower density case, resulting in an increased pedestal pressure, which indicates that the increased particle flux does not significantly degrade energy confinement. Modeling of cases with constant ∇B drift direction but changing between the more open lower divertor and more closed upper divertor show that there is increased fueling inside the pedestal with the more open geometry. As a result, the pedestal fueling rate for both attached and detached cases is always lower with more closed divertor geometry than in any cases with more open geometry.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ECSS..202..164B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ECSS..202..164B">Nearshore drift dynamics of natural versus artificial seagrass wrack</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Baring, Ryan J.; Fairweather, Peter G.; Lester, Rebecca E. 2018-03-01 Drifting macrophytes such as seagrass and macroalgae are commonly found washed ashore on sandy beaches but few studies have investigated the drift trajectories of macrophytes whilst near to the coast. This is the first study to investigate the surface drifting of small clumps of seagrass released at various distances from shore, across multiple days with contrasting wind and tidal conditions, in a large gulf in southern Australia. Natural and artificial radio-tagged seagrass units generally travelled in the same directions as tides but trajectories were variable across sampling days and when tagged units were released at different distances from shore. Natural and artificial units diverged from each other particularly on days when wind speeds increased but generally drifted in the same direction and ended up within close proximity to each other at the 6-h endpoint. During calm conditions, tagged seagrass units drifted with tides for 0.25-5 km and, during one sampling day when wind speeds increased, drifted for >5 km over the 6-h time period. Only tagged units that were released closest to shore stranded on sandy beaches within the six hours of observation, so it would be difficult to predict the eventual stranding location on shorelines for macrophytes released further offshore. This study provides evidence of the variability of macrophyte drift dynamics near to coastlines. Acknowledging this variability is essential for further understanding of the ecological significance of allochthonous material arriving at shorelines, which should be integrated into future research and management of sandy-beach ecosystems. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JSemi..32i4009H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JSemi..32i4009H">Built-in electric field thickness design for betavoltaic batteries</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Haiyang, Chen; Darang, Li; Jianhua, Yin; Shengguo, Cai 2011-09-01 Isotope source energy deposition along the thickness direction of a semiconductor is calculated, based upon which an ideal short current is evaluated for betavoltaic batteries. Electron-hole pair recombination and drifting length in a PN junction built-in electric field are extracted by comparing the measured short currents with the ideal short currents. A built-in electric field thickness design principle is proposed for betavoltaic batteries: after measuring the energy deposition depth and the carrier drift length, the shorter one should then be chosen as the built-in electric field thickness. If the energy deposition depth is much larger than the carrier drift length, a multi-junction is preferred in betavoltaic batteries and the number of the junctions should be the value of the deposition depth divided by the drift length. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MART38012B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MART38012B">Controlling qubit drift by recycling error correction syndromes</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Blume-Kohout, Robin 2015-03-01 Physical qubits are susceptible to systematic drift, above and beyond the stochastic Markovian noise that motivates quantum error correction. This parameter drift must be compensated - if it is ignored, error rates will rise to intolerable levels - but compensation requires knowing the parameters' current value, which appears to require halting experimental work to recalibrate (e.g. via quantum tomography). Fortunately, this is untrue. I show how to perform on-the-fly recalibration on the physical qubits in an error correcting code, using only information from the error correction syndromes. The algorithm for detecting and compensating drift is very simple - yet, remarkably, when used to compensate Brownian drift in the qubit Hamiltonian, it achieves a stabilized error rate very close to the theoretical lower bound. Against 1/f noise, it is less effective only because 1/f noise is (like white noise) dominated by high-frequency fluctuations that are uncompensatable. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70187992','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70187992">Deleterious effects of net clogging on the quantification of stream drift</a> <a target="_blank" rel="noopener noreferrer" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a> Muehlbauer, Jeffrey D.; Kennedy, Theodore A.; Copp, Adam J.; Sabol, Thomas 2017-01-01 Drift studies are central to stream and river ecological research. However, a fundamental aspect of quantifying drift — how net clogging affects the accuracy of results — has been widely ignored. Utilizing approaches from plankton and suspended sediment studies in oceanography and hydrology, we examined the rate and dynamics of net clogging across a range of conditions. We found that nets clog nonlinearly over time and that suspended solid concentrations and net mesh size exerted a strong effect on clogging rates. Critically, net clogging introduced unpredictable biases in resultant data due to the inaccuracies in water volume estimates introduced by progressive clogging. This renders the widespread approach to linearly “correct” for clogging inadequate. Using a meta-analysis of 77 drift studies spanning 25 years, we demonstrate that the detrimental effects of net clogging are routinely unappreciated, even though the results of most of these studies were likely affected by clogging. We close by describing an approach for avoiding net clogging, which will increase the accuracy and reproducibility of results in future freshwater, lotic drift studies. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SPIE.7742E..0VC','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SPIE.7742E..0VC">Development of a 3D CZT detector prototype for Laue Lens telescope</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Caroli, Ezio; Auricchio, Natalia; Del Sordo, Stefano; Abbene, Leonardo; Budtz-Jørgensen, Carl; Casini, Fabio; Curado da Silva, Rui M.; Kuvvetlli, Irfan; Milano, Luciano; Natalucci, Lorenzo; Quadrini, Egidio M.; Stephen, John B.; Ubertini, Pietro; Zanichelli, Massimiliano; Zappettini, Andrea 2010-07-01 We report on the development of a 3D position sensitive prototype suitable as focal plane detector for Laue lens telescope. The basic sensitive unit is a drift strip detector based on a CZT crystal, (~19×8 mm2 area, 2.4 mm thick), irradiated transversally to the electric field direction. The anode side is segmented in 64 strips, that divide the crystal in 8 independent sensor (pixel), each composed by one collecting strip and 7 (one in common) adjacent drift strips. The drift strips are biased by a voltage divider, whereas the anode strips are held at ground. Furthermore, the cathode is divided in 4 horizontal strips for the reconstruction of the third interaction position coordinate. The 3D prototype will be made by packing 8 linear modules, each composed by one basic sensitive unit, bonded on a ceramic layer. The linear modules readout is provided by a custom front end electronics implementing a set of three RENA-3 for a total of 128 channels. The front-end electronics and the operating logics (in particular coincidence logics for polarisation measurements) are handled by a versatile and modular multi-parametric back end electronics developed using FPGA technology. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22598973-particle-cell-simulation-study-lower-hybrid-shock','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22598973-particle-cell-simulation-study-lower-hybrid-shock">Particle-in-cell simulation study of a lower-hybrid shock</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Dieckmann, M. E.; Ynnerman, A.; Sarri, G. 2016-06-15 The expansion of a magnetized high-pressure plasma into a low-pressure ambient medium is examined with particle-in-cell simulations. The magnetic field points perpendicular to the plasma's expansion direction and binary collisions between particles are absent. The expanding plasma steepens into a quasi-electrostatic shock that is sustained by the lower-hybrid (LH) wave. The ambipolar electric field points in the expansion direction and it induces together with the background magnetic field a fast E cross B drift of electrons. The drifting electrons modify the background magnetic field, resulting in its pile-up by the LH shock. The magnetic pressure gradient force accelerates the ambientmore » ions ahead of the LH shock, reducing the relative velocity between the ambient plasma and the LH shock to about the phase speed of the shocked LH wave, transforming the LH shock into a nonlinear LH wave. The oscillations of the electrostatic potential have a larger amplitude and wavelength in the magnetized plasma than in an unmagnetized one with otherwise identical conditions. The energy loss to the drifting electrons leads to a noticeable slowdown of the LH shock compared to that in an unmagnetized plasma.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.2024L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.2024L">On the origin of the crescent-shaped distributions observed by MMS at the magnetopause</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lapenta, G.; Berchem, J.; Zhou, M.; Walker, R. J.; El-Alaoui, M.; Goldstein, M. L.; Paterson, W. R.; Giles, B. L.; Pollock, C. J.; Russell, C. T.; Strangeway, R. J.; Ergun, R. E.; Khotyaintsev, Y. V.; Torbert, R. B.; Burch, J. L. 2017-02-01 MMS observations recently confirmed that crescent-shaped electron velocity distributions in the plane perpendicular to the magnetic field occur in the electron diffusion region near reconnection sites at Earth's magnetopause. In this paper, we reexamine the origin of the crescent-shaped distributions in the light of our new finding that ions and electrons are drifting in opposite directions when displayed in magnetopause boundary-normal coordinates. Therefore, E × B drifts cannot cause the crescent shapes. We performed a high-resolution multiscale simulation capturing subelectron skin-depth scales. The results suggest that the crescent-shaped distributions are caused by meandering orbits without necessarily requiring any additional processes found at the magnetopause such as the highly asymmetric magnetopause ambipolar electric field. We use an adiabatic Hamiltonian model of particle motion to confirm that conservation of canonical momentum in the presence of magnetic field gradients causes the formation of crescent shapes without invoking asymmetries or the presence of an E × B drift. An important consequence of this finding is that we expect crescent-shaped distributions also to be observed in the magnetotail, a prediction that MMS will soon be able to test. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SuMi...36..455Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SuMi...36..455Z">Energy and momentum relaxation of electrons in bulk and 2D GaN</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zanato, D.; Balkan, N.; Hill, G.; Schaff, W. J. 2004-10-01 We present our experimental and theoretical studies regarding the energy and momentum relaxation of hot electrons in n-type bulk GaN and AlGaN/GaN HEMT structures. We determine the non-equilibrium temperatures and the energy relaxation rates in the steady state using the mobility mapping technique together with the power balance conditions as described by us elsewhere [N. Balkan, M.C. Arikan, S. Gokden, V. Tilak, B. Schaff, R.J. Shealy, J. Phys.: Condens. Matter 14 (2002) 3457]. We obtain the e-LO phonon scattering time of 8 fs and show that the power loss of electrons due to optical phonon emission agrees with the theoretical prediction. The drift velocity-field curves at high electric fields indicate that the drift velocity saturates at approximately 3×10 6 cm/s for the two-dimensional structure and 4×10 6 cm/s for the bulk material at 77 K. These values are much lower than those predicted by the existing theories. A critical analysis of the observations is given with a model taking into account of the non-drifting non-equilibrium phonon production. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1238237-nonlinear-simulations-peeling-ballooning-modes-anomalous-electron-viscosity-role-edge-localized-mode-crashes','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1238237-nonlinear-simulations-peeling-ballooning-modes-anomalous-electron-viscosity-role-edge-localized-mode-crashes">Nonlinear simulations of peeling-ballooning modes with anomalous electron viscosity and their role in edge localized mode crashes</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Xu, X. Q.; Dudson, B.; Snyder, P. B.; ... 2010-10-22 A minimum set of equations based on the peeling-ballooning (P-B) model with nonideal physics effects (diamagnetic drift, E×B drift, resistivity, and anomalous electron viscosity) is found to simulate pedestal collapse when using the new BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Nonlinear simulations of P-B modes demonstrate that the P-B modes trigger magnetic reconnection, which leads to the pedestal collapse. With the addition of a model of the anomalous electron viscosity under the assumption that the electron viscosity is comparable to the anomalous electron thermal diffusivity, it is found from simulations using a realisticmore » high-Lundquist number that the pedestal collapse is limited to the edge region and the edge localized mode (ELM) size is about 5–10% of the pedestal stored energy. Furthermore, this is consistent with many observations of large ELMs.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PSST...26b4008L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PSST...26b4008L">Characteristics and transport effects of the electron drift instability in Hall-effect thrusters</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lafleur, T.; Baalrud, S. D.; Chabert, P. 2017-02-01 The large electron {E}× {B} drift (relative to the ions) in the azimuthal direction of Hall-effect thrusters is well known to excite a strong instability. In a recent paper (Lafleur et al 2016 Phys. Plasmas 23 053503) we demonstrated that this instability leads to an enhanced electron-ion friction force that increases the electron cross-field mobility to levels similar to those seen experimentally. Here we extend this work by considering in detail the onset criteria for the formation of this instability (both in xenon, and other propellants of interest), and identify a number of important characteristics that it displays within Hall-effect thrusters (HETs): including the appearance of an additional non-dimensionalized scaling parameter (the instability growth-to-convection ratio), which controls the instability evolution and amplitude. We also investigate the effect that the instability has on electron and ion heating in HETs, and show that it leads to an ion rotation in the azimuthal direction that is in agreement with that seen experimentally. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026547','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026547">The dependence of solar modulation on the sign of the cosmic ray particle charge</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Garcia-Munoz, M.; Meyer, P.; Pyle, K. R.; Simpson, J. A.; Evenson, P. A. 1985-01-01 The solar modulation of galactic cosmic ray helium and electrons at 1 AU, within the 600-1000 MV magnetic rigidity interval, are compared for the period from 1965 through 1984. The time-intensity variations during the two solar maxima around 1970 and 1981 show that after 1970 the helium intensity recovers earlier than that of the electrons, whereas after 1981 the electron intensity recovers earlier than that of helium. The flux ratio of helium to electrons (He/e) undergoes a major increases during the 1969-1971 period and a major decrease during 1979-83. These experimental results can be interpreted as due to a dependence of the solar modulation of galactic cosmic rays on the sign of the particle charge, possibly as a consequence of drifts due to gradients and curvatures in the interplanetary magnetic field. However, the comparison of the shapes of the intensity-time curves of helium and electrons in the period 1970-1981 does not support a major specific prediction of the drift model. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21517603','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21517603">Conditions and growth rate of Rayleigh instability in a Hall thruster under the effect of ion temperature.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Malik, Hitendra K; Singh, Sukhmander 2011-03-01 Rayleigh instability is investigated in a Hall thruster under the effect of finite temperature and density gradient of the plasma species. The instability occurs only when the frequency of the oscillations ω falls within a frequency band described by k{y}u₀+1/k_{y}∂²u_{0}/∂x²+Ω/k_{y}n_{0}∂n₀/∂x≪ω<sqrt[Y{i}T{i}k{y}²/M+ω{p}{i}²(Ω²+Y{e}T{e}k{y}²/m)/(ω{p}{e}²+Ω²+Y{e}T{e}k{y}²/m], where u₀ is the drift velocity of the electrons, Ω is their gyration frequency under the effect of the magnetic field, k{y} is the wave propagation constant, n₀ is the plasma density together with ∂n₀/∂x as the density gradient, and T{i}(T{e}), M(m), Y{i}(Y{e}), and ω{p}{i}(ω{p}{e}) are the temperature, mass, specific heat ratio, and plasma frequency of the ions (electrons), respectively. A relevant Rayleigh equation is derived and solved numerically using the fourth-order Runge-Kutta method for investigating the perturbed potential under the effect of electron drift velocity, channel length, magnetic field, ion temperature, and electron temperature. The instability grows faster because of the magnetic field, ion temperature, and drift velocity of the electrons but its growth rate is reduced because of the electron temperature, channel length, and also its far distances from the anode. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DPPCP9118J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DPPCP9118J">Physical requirements and milestones for the HIT-PoP Experiment</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jarboe, Thomas 2011-10-01 Recent success with HIT-SI demonstrates the viability of steady inductive helicity injection (SIHI) as a spheromak formation and sustainment method. Results include the sustainment of toroidal current of over 50 kA, up to 40 kA of plasma current that is separate from the injectors, toroidal flux up to 6 times the peak injected flux, and j/n > 1014Am. All were achieved with 10MW or less applied power. This paper explores the requirements for a confinement test of the concept using a larger proof of principle experiment. The confinement experiment must not exceed the beta limit, the drift parameter limit, or the wall loading limit, where the drift parameter is (drift of electrons relative to ions to produce current)/(ion thermal speed). It must also exceed a minimum j/n, a minimum n a, and a minimum electron temperature, where a is the minor radius. The drift parameter limit and beta limit appear to play defining roles in spheromak performance leading to a very favorable scaling of wall loading with size. The milestones sequence suggested is the following: 1. Startup at drift parameter and beta limit minimum density. 2. Raise current until j/n exceeds 10-14Am. 3. Raise the current and temperature until T ~ 50 eV for good ionization. 4. Raise the current and density until n a > 2x1019 m-2 for neutral screening. 5. Raise current and temperature until T > 200eV so magnetic confinement can be studied. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830024572','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830024572">Electric thruster research</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kaufman, H. R.; Robinson, R. S. 1982-01-01 It has been customary to assume that ions flow nearly equally in all directions from the ion production region within an electron-bombardment discharge chamber. In general, the electron current through a magnetic field can alter the electron density, and hence the ion density, in such a way that ions tend to be directed away from the region bounded by the magnetic field. When this mechanism is understood, it becomes evident that many past discharge chamber designs have operated with a preferentially directed flow of ions. Thermal losses were calculated for an oxide-free hollow cathode. At low electron emissions, the total of the radiation and conduction losses agreed with the total discharge power. At higher emissions, though, the plasma collisions external to the cathode constituted an increasingly greater fraction of the discharge power. Experimental performance of a Hall-current thruster was adversely affected by nonuniformities in the magnetic field, produced by the cathode heating current. The technology of closed-drift thrusters was reviewed. The experimental electron diffusion in the acceleration channel was found to be within about a factor of 3 of the Bohm value for the better thruster designs at most operating conditions. Thruster efficiencies of about 0.5 appear practical for the 1000 to 2000 s range of specific impulse. Lifetime information is limited, but values of several thousands of hours should be possible with anode layer thrusters operated or = to 2000 s. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880059325&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DButterfly','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880059325&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DButterfly">A statistical study of ion pitch-angle distributions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sibeck, D. G.; Mcentire, R. W.; Lui, A. T. Y.; Krimigis, S. M. 1987-01-01 Preliminary results of a statistical study of energetic (34-50 keV) ion pitch-angle distributions (PADs) within 9 Re of earth provide evidence for an orderly pattern consistent with both drift-shell splitting and magnetopause shadowing. Normal ion PADs dominate the dayside and inner magnetosphere. Butterfly PADs typically occur in a narrow belt stretching from dusk to dawn through midnight, where they approach within 6 Re of earth. While those ion butterfly PADs that typically occur on closed drift paths are mainly caused by drift-shell splitting, there is also evidence for magnetopause shadowing in observations of more frequent butterfly PAD occurrence in the outer magnetosphere near dawn than dusk. Isotropic and gradient boundary PADs terminate the tailward extent of the butterfly ion PAD belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720011673','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720011673">Model development of supersonic trough wind with shocks</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Grebowsky, J. M. 1972-01-01 The time dependent one dimensional hydrodynamic equations describe the evolution of the thermal plasma flow along closed magnetic field lines outside of the plasmasphere. The convection of the supersonic polar wind onto a closed fieldline results in the assumed formation of collisionless plasma shocks. These shocks move earthward as the field line with its frozen-in plasma remains fixed or contracts with time to smaller L coordinates. The high equatorial plasma temperature (of the order of electron volts) produced by the shock process decreases with time if the flow is isothermal but it will increase if the contraction is under adiabatic conditions. Assuming adiabaticity a peak in the temperature forms at the equator in conjunction with a depression in the ion density. After an initial contraction, if the flux tube drifts to higher L coordinates the direction of the shock motion can be reversed so that the supersonic region will expand along the field line towards the state characterizing the supersonic polar wind. A rapid expansion will lower the equatorial density while the temperature decreases with time under adiabatic but not isothermal conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050160217&hterms=grain+dust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgrain%2Bdust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050160217&hterms=grain+dust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgrain%2Bdust">Interactions of Dust Grains with Coronal Mass Ejections and Solar Cycle Variations of the F-Coronal Brightness</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ragot, B. R.; Kahler, S. W. 2003-01-01 The density of interplanetary dust increases sunward to reach its maximum in the F corona, where its scattered white-light emission dominates that of the electron K corona above about 3 Solar Radius. The dust will interact with both the particles and fields of antisunward propagating coronal mass ejections (CMEs). To understand the effects of the CME/dust interactions we consider the dominant forces, with and without CMEs. acting on the dust in the 3-5 Solar Radius region. Dust grain orbits are then computed to compare the drift rates from 5 to 3 Solar Radius. for periods of minimum and maximum solar activity, where a simple CME model is adopted to distinguish between the two periods. The ion-drag force, even in the quiet solar wind, reduces the drift time by a significant factor from its value estimated with the Poynting-Robertson drag force alone. The ion-drag effects of CMEs result in even shorter drift times of the large (greater than or approx. 3 microns) dust grains. hence faster depletion rates and lower dust-pain densities, at solar maxima. If dominated by thermal emission, the near-infrared brightness will thus display solar cycle variations close to the dust plane of symmetry. While trapping the smallest of the grains, the CME magnetic fields also scatter the grains of intermediate size (0.1-3 microns) in latitude. If light scattering by small grains close to the Sun dominates the optical brightness. the scattering by the CME magnetic fields will result in a solar cycle variation of the optical brightness distribution not exceeding 100% at high latitudes, with a higher isotropy reached at solar maxima. A good degree of latitudinal isotropy is already reached at low solar activity since the magnetic fields of the quiet solar wind so close to the Sun are able to scatter the small (less than or approx. 3 microns) grains up to the polar regions in only a few days or less, producing strong perturbations of their trajectories in less than half their orbital periods. Finally, we consider possible observable consequences of individual CME/dust interactions. We show that the dust grains very likely have no observable effect on the dynamics of CMEs. The effect of an individual CME on the dust grains, however, might serve as a forecasting tool for the directions and amplitudes of the magnetic fields within the CME. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22492839-kinetics-optically-excited-charge-carriers-gan-surface-influence-catalytic-pt-nanostructures','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22492839-kinetics-optically-excited-charge-carriers-gan-surface-influence-catalytic-pt-nanostructures">Kinetics of optically excited charge carriers at the GaN surface: Influence of catalytic Pt nanostructures</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Winnerl, Andrea, E-mail: andrea.winnerl@wsi.tum.de; Pereira, Rui N.; Stutzmann, Martin 2015-10-21 In this work, we use GaN with different deposited Pt nanostructures as a controllable model system to investigate the kinetics of photo-generated charge carriers in hybrid photocatalysts. We combine conductance and contact potential difference measurements to investigate the influence of Pt on the processes involved in the capture and decay of photo-generated charge carriers at and close to the GaN surface. We found that in the presence of Pt nanostructures the photo-excitation processes are similar to those found in Pt free GaN. However, in GaN with Pt nanostructures, photo-generated holes are preferentially trapped in surface states of the GaN coveredmore » with Pt and/or in electronic states of the Pt and lead to an accumulation of positive charge there, whereas negative charge is accumulated in localized states in a shallow defect band of the GaN covered with Pt. This preferential accumulation of photo-generated electrons close to the surface is responsible for a dramatic acceleration of the turn-off charge transfer kinetics and a stronger dependence of the surface photovoltage on light intensity when compared to a Pt free GaN surface. Our study shows that in hybrid photocatalysts, the metal nanostructures induce a spatially inhomogeneous surface band bending of the semiconductor that promotes a lateral drift of photogenerated charges towards the catalytic nanostructures.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhCS.390a2073K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhCS.390a2073K">Experimental Investigation of Pseudospark generated electron beam</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kumar, Niraj; Verma, D. K.; Prajapati, J.; Kumar, M.; Meena, B. L.; Tyagi, M. S.; Srivastava, V.; Pal, U. N. 2012-11-01 The pseudospark (PS) discharge is, however, more recently recognized as a different type of discharge which is capable of generating electron beams with the highest combined current density and brightness of any known type of electron source. PS discharge is a specific type of gas discharge, which operates on the left-hand side of the hollow cathode analogy to the Paschen curve with axially symmetric parallel electrodes and central holes on the electrodes. The PS discharge generated electron beam has tremendous applications in plasma filled microwave sources where normal material cathode cannot be used. Analysis of the electron beam profile has been carried out experimentally for different applied voltages. The investigation has been done at different axial and radial location inside the drift tube in argon atmosphere. This paper represents experimentally derived axial and radial variation of the beam current inside the plasma filled drift tube of PS discharge based plasma cathode electron (PCE) gun. With the help of current density estimation the focusing and defocusing point of electron beam in axial direction can be analyzed. It has been further confirmed the successful propagation of electron beam in confined manner without any assistance of external magnetic field. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active">15</li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active">16</li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996APS..GECTUPB11W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996APS..GECTUPB11W">Boltzmann Calculations of Electron Transport in CF4 and CF_4/Ar</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wang, Yicheng; van Brunt, R. J. 1996-10-01 A new set of electron collisional cross sections(L. G. Christophorou, J. K. Olthoff, and M. V. V. S. Rao, J. Phys. Chem. Ref. Data, submitted (May 1996)) for CF4 has been proposed, based primarily upon available experimental measurements. In this paper we present the results of calculations of the drift velocity, ionization coefficient, and attachment coefficient for electrons in CF4 based upon the new cross section set, using a two-term Boltzmann calculation. Comparison of results with experimental determinations of the transport parameters, such as drift velocity, are presented, along with comparison of results obtained using two previously pubished(M. Hyashi, in Swarm Studies and Elastic Electron-Molecule Collisions) (1987); and Y. Nakamura in Gaseous Electronics and Their Applications (1991) electron impact cross section sets for CF_4. Additions and adjustments to the cross section sets required for the model to achieve consitency with transport data are discussed. - Research sponsored in part by the U.S. Air Force Wright Laboratory under contract F33615-96-C-2600 with the University of Tennessee. Also, Department of Physics, The University of Tennessee, Knoxville, TN. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/1402655-relativistic-electron-dynamics-produced-azimuthally-localized-poloidal-mode-ulf-waves-boomerang-shaped-pitch-angle-evolutions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1402655-relativistic-electron-dynamics-produced-azimuthally-localized-poloidal-mode-ulf-waves-boomerang-shaped-pitch-angle-evolutions">Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hao, Y. X.; Zong, Q. -G.; Zhou, X. -Z. Here, we present an analysis of “boomerang-shaped” pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact withmore » electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PSST...23f5040H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PSST...23f5040H">Effect of electron Monte Carlo collisions on a hybrid simulation of a low-pressure capacitively coupled plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hwang, Seok Won; Lee, Ho-Jun; Lee, Hae June 2014-12-01 Fluid models have been widely used and conducted successfully in high pressure plasma simulations where the drift-diffusion and the local-field approximation are valid. However, fluid models are not able to demonstrate non-local effects related to large electron energy relaxation mean free path in low pressure plasmas. To overcome this weakness, a hybrid model coupling electron Monte Carlo collision (EMCC) method with the fluid model is introduced to obtain precise electron energy distribution functions using pseudo-particles. Steady state simulation results by a one-dimensional hybrid model which includes EMCC method for the collisional reactions but uses drift-diffusion approximation for electron transport in a fluid model are compared with those of a conventional particle-in-cell (PIC) and a fluid model for low pressure capacitively coupled plasmas. At a wide range of pressure, the hybrid model agrees well with the PIC simulation with a reduced calculation time while the fluid model shows discrepancy in the results of the plasma density and the electron temperature. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM11B2302H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM11B2302H">Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hao, Y.; Zong, Q.; Zhou, X.; Rankin, R.; Chen, X.; Liu, Y.; Fu, S.; Spence, H. E.; Blake, J. B.; Reeves, G. D. 2017-12-01 We present an analysis of "boomerang-shaped" pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on June 7th, 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90º pitch angle electrons, the phase change of the flux modulations across energy exceeds 180º, and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wave field reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift-resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.7618H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.7618H">Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hao, Y. X.; Zong, Q.-G.; Zhou, X.-Z.; Rankin, R.; Chen, X. R.; Liu, Y.; Fu, S. Y.; Spence, H. E.; Blake, J. B.; Reeves, G. D. 2017-08-01 We present an analysis of "boomerang-shaped" pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820016894','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820016894">Investigation of the winds and electron concentration variability in the D region of the ionosphere by the partial-reflection radar technique</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Weiland, R. M.; Bowhill, S. A. 1981-01-01 The development and first observations of the partial-reflection drifts experiment at Urbana, Illinois (40 N) are described. The winds data from the drifts experiment are compared with electron concentration data obtained by the differential-absorption technique to study the possible meteorological causes of the winter anomaly in the mesosphere at midlatitudes. winds data obtained by the meteor-radar experiment at Urbana are also compared with electron concentration data measured at Urban. A significant correlation is shown is both cases between southward winds and increasing electron concentration measured at the same location during winter. The possibility of stratospheric/mesospheric coupling is investigated by comparing satellite-measured 0.4 mbar geopotential data with mesospheric electron concentration data. No significant coupling was observed. The winds measured at Saskatoon, Saskatchewan (52 N) are compared with the electron concentrations measured at Urban, yielding constant fixed relationship, but significant correlations for short segments of the winter. A significant coherence is observed at discrete frequencies during segments of the winter. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1402655-relativistic-electron-dynamics-produced-azimuthally-localized-poloidal-mode-ulf-waves-boomerang-shaped-pitch-angle-evolutions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1402655-relativistic-electron-dynamics-produced-azimuthally-localized-poloidal-mode-ulf-waves-boomerang-shaped-pitch-angle-evolutions">Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Hao, Y. X.; Zong, Q. -G.; Zhou, X. -Z.; ... 2017-07-10 Here, we present an analysis of “boomerang-shaped” pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact withmore » electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780000551&hterms=sniffer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsniffer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780000551&hterms=sniffer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsniffer">Refrigerant leak detector</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Byrne, E. J. 1979-01-01 Quantitative leak detector visually demonstrates refrigerant loss from precision volume of large refrigeration system over established period of time from single test point. Mechanical unit is less costly than electronic "sniffers" and is more reliable due to absence of electronic circuits that are susceptible to drift. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770005580','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770005580">Analysis of epitaxial drift field N on P silicon solar cells</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Baraona, C. R.; Brandhorst, H. W., Jr. 1976-01-01 The performance of epitaxial drift field silicon solar cell structures having a variety of impurity profiles was calculated. These structures consist of a uniformly doped P-type substrate layer, and a P-type epitaxial drift field layer with a variety of field strengths. Several N-layer structures were modeled. A four layer solar cell model was used to calculate efficiency, open circuit voltage and short circuit current. The effect on performance of layer thickness, doping level, and diffusion length was determined. The results show that peak initial efficiency of 18.1% occurs for a drift field thickness of about 30 micron with the doping rising from 10 to the 17th power atoms/cu cm at the edge of the depletion region to 10 to the 18th power atoms/cu cm in the substrate. Stronger drift fields (narrow field regions) allowed very high performance (17% efficiency) even after irradiation to 3x10 to the 14th power 1 MeV electrons/sq cm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1704c0014A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1704c0014A">Hough transform method for track finding in center drift chamber</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Azmi, K. A. Mohammad Kamal; Wan Abdullah, W. A. T.; Ibrahim, Zainol Abidin 2016-01-01 Hough transform is a global tracking method used which had been expected to be faster approach for tracking the circular pattern of electron moving in Center Drift Chamber (CDC), by transforming the point of hit into a circular curve. This paper present the implementation of hough transform method for the reconstruction of tracks in Center Drift Chamber (CDC) which have been generated by random number in C language programming. Result from implementation of this method shows higher peak of circle parameter value (xc,yc,rc) that indicate the similarity value of the parameter needed for circular track in CDC for charged particles in the region of CDC. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915070P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915070P">Controls on late Holocene drift-sand dynamics: the role of people and climate on inland aeolian activity in the Netherlands</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pierik, Harm Jan; Van Lanen, Rowin; Gouw-Bouman, Marjolein; Groenewoudt, Bert; Wallinga, Jakob; Hoek, Wim 2017-04-01 Holocene drift-sand activity is commonly linked directly to either population pressure (via agricultural activity) or to climate change (e.g. storminess). In the Pleistocene sand areas of the Netherlands small-scale Holocene aeolian activity occurred since the Neolithic, whereas large scale drift-sand activity started during the Middle Ages (especially after AD 1000. This last phase coincides with the intensification of farming and demographic pressure, but is also commonly associated with a colder climate and enhanced storminess. This raises the question to what extent drift-sand activity can be attributed to human activities or to natural forcing factors. In this study we compare the spatial and chronological patterns of drift-sand occurrence for four characteristic Pleistocene sand regions in the Netherlands. For this, we compiled a new supra-regional overview of dates related to drift-sand activity (14C, OSL, archaeological and historical), that we compared with existing national soil maps, historical-route networks, and vegetation and climate reconstructions. Results show a steady occurrence of aeolian activity between 1000 BC and AD 1000, interrupted by remarkable dip in aeolian activity around 2000 BP, probably caused by changing land-use practices or by lower storminess. It is evident that human pressure on the landscape was most influential on initiating sand drifting: this is supported by more frequent occurrence close to routes and the uninterrupted increase in drift-sand activity after ca AD 1000 during periods of high population density and large-scale deforestation. Once triggered by human activities, the drift-sand development was probably further enhanced several centuries later during the cold and more stormy Little Ice Age (AD 1570-1900). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS1005a2046W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS1005a2046W">Analysis of type II and type III solar radio bursts</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wijesekera, J. V.; Jayaratne, K. P. S. C.; Adassuriya, J. 2018-04-01 Solar radio burst is an arrangement of a frequency space that variation with time. Most of radio burst can be identified in low frequency range such as below 200 MHz and depending on frequencies. Solar radio bursts were the first phenomenon identified in the field of radio astronomy field. Solar radio frequency range is from 70 MHz to 2.2 GHz. Most of the radio burst can be identified in a low frequency range such as below 200 MHz. Properties of low-frequency radio were analyzed this research. There are two types of solar radio bursts were analyzed, named as type II and type III radio bursts. Exponential decay type could be seen in type II, and a linear could be indicated in type III solar radio bursts. The results of the drift rate graphs show the values of each chosen solar radio burst. High drift rate values can be seen in type III solar flares whereas low to medium drift rate values can be seen in type II solar flares. In the second part of the research the Newkirk model electron density model was used to estimate the drift velocities of the solar radio bursts. Although the special origin of the solar radio burst is not known clearly we assumed. The chosen solar radio bursts were originated within the solar radius of 0.9 - 1.3 range from the photosphere. We used power low in the form of (x) = A × 10‑bx were that the electron density related to the height of the solar atmosphere. The calculation of the plasma velocity of each solar radio burst was done using the electron density model and drift rates. Therefore velocity of chosen type II solar radio bursts indicates low velocities. The values are 233.2499 Km s‑1, 815.9522 Km s‑1 and 369.5425 Km s‑1. Velocity of chosen type III solar radio bursts were 1443.058 Km s‑1and 1205.05Km s ‑1. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599964-anomalous-pinch-turbulent-plasmas-driven-magnetic-drift-induced-lorentz-force-through-stokes-einstein-relation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599964-anomalous-pinch-turbulent-plasmas-driven-magnetic-drift-induced-lorentz-force-through-stokes-einstein-relation">Anomalous pinch of turbulent plasmas driven by the magnetic-drift-induced Lorentz force through the Stokes-Einstein relation</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Wang, Shaojie, E-mail: wangsj@ustc.edu.cn It is found that the Lorentz force generated by the magnetic drift drives a generic plasma pinch flux of particle, energy and momentum through the Stokes-Einstein relation. The proposed theoretical model applies for both electrons and ions, trapped particles, and passing particles. An anomalous parallel current pinch due to the electrostatic turbulence with long parallel wave-length is predicted. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PPCF...58l5012M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PPCF...58l5012M">Analysis of drift effects on the tokamak power scrape-off width using SOLPS-ITER</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Meier, E. T.; Goldston, R. J.; Kaveeva, E. G.; Makowski, M. A.; Mordijck, S.; Rozhansky, V. A.; Senichenkov, I. Yu; Voskoboynikov, S. P. 2016-12-01 SOLPS-ITER, a comprehensive 2D scrape-off layer modeling package, is used to examine the physical mechanisms that set the scrape-off width ({λq} ) for inter-ELM power exhaust. Guided by Goldston’s heuristic drift (HD) model, which shows remarkable quantitative agreement with experimental data, this research examines drift effects on {λq} in a DIII-D H-mode magnetic equilibrium. As a numerical expedient, a low target recycling coefficient of 0.9 is used in the simulations, resulting in outer target plasma that is sheath limited instead of conduction limited as in the experiment. Scrape-off layer (SOL) particle diffusivity (D SOL) is scanned from 1 to 0.1 m2 s-1. Across this diffusivity range, outer divertor heat flux is dominated by a narrow (˜3-4 mm when mapped to the outer midplane) electron convection channel associated with thermoelectric current through the SOL from outer to inner divertor. An order-unity up-down ion pressure asymmetry allows net ion drift flux across the separatrix, facilitated by an artificial mechanism that mimics the anomalous electron transport required for overall ambipolarity in the HD model. At {{D}\\text{SOL}}=0.1 m2 s-1, the density fall-off length is similar to the electron temperature fall-off length, as predicted by the HD model and as seen experimentally. This research represents a step toward a deeper understanding of the power scrape-off width, and serves as a basis for extending fluid modeling to more experimentally relevant, high-collisionality regimes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RaSc...51.1818M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RaSc...51.1818M">Assimilation of thermospheric measurements for ionosphere-thermosphere state estimation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Miladinovich, Daniel S.; Datta-Barua, Seebany; Bust, Gary S.; Makela, Jonathan J. 2016-12-01 We develop a method that uses data assimilation to estimate ionospheric-thermospheric (IT) states during midlatitude nighttime storm conditions. The algorithm Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE) uses time-varying electron densities in the F region, derived primarily from total electron content data, to estimate two drivers of the IT: neutral winds and electric potential. A Kalman filter is used to update background models based on ingested plasma densities and neutral wind measurements. This is the first time a Kalman filtering technique is used with the EMPIRE algorithm and the first time neutral wind measurements from 630.0 nm Fabry-Perot interferometers (FPIs) are ingested to improve estimates of storm time ion drifts and neutral winds. The effects of assimilating remotely sensed neutral winds from FPI observations are studied by comparing results of ingesting: electron densities (N) only, N plus half the measurements from a single FPI, and then N plus all of the FPI data. While estimates of ion drifts and neutral winds based on N give estimates similar to the background models, this study's results show that ingestion of the FPI data can significantly change neutral wind and ion drift estimation away from background models. In particular, once neutral winds are ingested, estimated neutral winds agree more with validation wind data, and estimated ion drifts in the magnetic field-parallel direction are more sensitive to ingestion than the field-perpendicular zonal and meridional directions. Also, data assimilation with FPI measurements helps provide insight into the effects of contamination on 630.0 nm emissions experienced during geomagnetic storms. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1335693-analysis-drift-effects-tokamak-power-scrape-off-width-using-solps-iter','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1335693-analysis-drift-effects-tokamak-power-scrape-off-width-using-solps-iter">Analysis of drift effects on the tokamak power scrape-off width using SOLPS-ITER</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Meier, E. T.; Goldston, R. J.; Kaveeva, E. G.; ... 2016-11-02 SOLPS-ITER, a comprehensive 2D scrape-off layer modeling package, is used to examine the physical mechanisms that set the scrape-off width (more » $${{\\lambda}_{q}}$$ ) for inter-ELM power exhaust. Guided by Goldston's heuristic drift (HD) model, which shows remarkable quantitative agreement with experimental data, this research examines drift effects on $${{\\lambda}_{q}}$$ in a DIII-D H-mode magnetic equilibrium. As a numerical expedient, a low target recycling coefficient of 0.9 is used in the simulations, resulting in outer target plasma that is sheath limited instead of conduction limited as in the experiment. Scrape-off layer (SOL) particle diffusivity (D SOL) is scanned from 1 to 0.1 m2 s –1. Across this diffusivity range, outer divertor heat flux is dominated by a narrow (~3–4mm when mapped to the outer midplane) electron convection channel associated with thermoelectric current through the SOL from outer to inner divertor. An order-unity up–down ion pressure asymmetry allows net ion drift flux across the separatrix, facilitated by an artificial mechanism that mimics the anomalous electron transport required for overall ambipolarity in the HD model. At $${{D}_{\\text{SOL}}}=0.1$$ m2 s –1, the density fall-off length is similar to the electron temperature fall-off length, as predicted by the HD model and as seen experimentally. Furthermore, this research represents a step toward a deeper understanding of the power scrape-off width, and serves as a basis for extending fluid modeling to more experimentally relevant, high-collisionality regimes.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29705338','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29705338">Correcting sample drift using Fourier harmonics.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Bárcena-González, G; Guerrero-Lebrero, M P; Guerrero, E; Reyes, D F; Braza, V; Yañez, A; Nuñez-Moraleda, B; González, D; Galindo, P L 2018-07-01 During image acquisition of crystalline materials by high-resolution scanning transmission electron microscopy, the sample drift could lead to distortions and shears that hinder their quantitative analysis and characterization. In order to measure and correct this effect, several authors have proposed different methodologies making use of series of images. In this work, we introduce a methodology to determine the drift angle via Fourier analysis by using a single image based on the measurements between the angles of the second Fourier harmonics in different quadrants. Two different approaches, that are independent of the angle of acquisition of the image, are evaluated. In addition, our results demonstrate that the determination of the drift angle is more accurate by using the measurements of non-consecutive quadrants when the angle of acquisition is an odd multiple of 45°. Copyright © 2018 Elsevier Ltd. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA11A2236Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA11A2236Y">Gradient Drift Turbulence from Electron Bite-Outs: Dependence on Atmospheric Parameters.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Young, M.; Oppenheim, M. M.; Dimant, Y. S. 2017-12-01 Electron bite-outs are regions of decreased electron density without a corresponding decrease in ion density, often caused by electron attachment to dust grains. They typically occur in the upper D-/lower E-region ionosphere and the accompanying electron gradient provides free energy to drive the gradient drift instability (GDI). The major difference between classical GDI and electron bite-out driven GDI is that the instability occurs on the top side of the bite-out region in the latter, as opposed to the bottom side in the former, in the presence of a vertical background electric field. Moreover, the mobile plasma population contains a gradient in only one species while the entire system remains quasineutral. This modified geometry presents new pathways for instabilities as the ions build up near the bite-out layer, leaving behind depletions that ascend away from the layer. Previous simulation runs showed that the presence of an electron gradient drives GDI-like turbulence even when ions and electrons start in momentum balance. Furthermore, a simulation run that replaced the electron bite-out with a layer of enhanced ion density, as though ions and electrons had filled in the bite-out region, did not lead to instability. This work examines the role of atmospheric parameters at altitudes between 80-100 km in instability formation and turbulence development, including the role of collisions in impeding instability growth as altitude decreases. Key parameters include the ambient electric field, which plays a critical role in triggering the gradient-drift instability; collision frequencies and temperature, which vary with altitude and effect the turbulent growth rate; and relative charge density of the bite-out, which increases the electron gradient strength. This work provides insight into how electron bite-out layers can produce turbulence that ground-based high frequency (HF) radars may be able to observe. The upper D-/lower E-region ionosphere is generally difficult to study in situ, making simulations of ground-based observables much more important. Assuming that electron bite-out layers result from dust charging in particular will allow the community to use the predictions of this work to study the ionospheric dust population. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ITNS...62.1741U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ITNS...62.1741U">Readout Electronics for the Central Drift Chamber of the Belle-II Detector</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Uchida, Tomohisa; Taniguchi, Takashi; Ikeno, Masahiro; Iwasaki, Yoshihito; Saito, Masatoshi; Shimazaki, Shoichi; Tanaka, Manobu M.; Taniguchi, Nanae; Uno, Shoji 2015-08-01 We have developed readout electronics for the central drift chamber (CDC) of the Belle-II detector. The space near the endplate of the CDC for installation of the electronics was limited by the detector structure. Due to the large amounts of data generated by the CDC, a high-speed data link, with a greater than one gigabit transfer rate, was required to transfer the data to a back-end computer. A new readout module was required to satisfy these requirements. This module processes 48 signals from the CDC, converts them to digital data and transfers it directly to the computer. All functions that transfer digital data via the high speed link were implemented on the single module. We have measured its electrical characteristics and confirmed that the results satisfy the requirements of the Belle-II experiment. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22391441-study-negative-hydrogen-ion-beam-optics-using-pic-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22391441-study-negative-hydrogen-ion-beam-optics-using-pic-model">Study of negative hydrogen ion beam optics using the 3D3V PIC model</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Miyamoto, K., E-mail: kmiyamot@naruto-u.ac.jp; Nishioka, S.; Goto, I. The mechanism of negative ion extraction under real conditions with the complex magnetic field is studied by using the 3D PIC simulation code. The extraction region of the negative ion source for the negative ion based neutral beam injection system in fusion reactors is modelled. It is shown that the E x B drift of electrons is caused by the magnetic filter and the electron suppression magnetic field, and the resultant asymmetry of the plasma meniscus. Furthermore, it is indicated that that the asymmetry of the plasma meniscus results in the asymmetry of negative ion beam profile including the beammore » halo. It could be demonstrated theoretically that the E x B drift is not significantly weakened by the elastic collisions of the electrons with neutral particles.« less </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active">16</li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active">17</li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhRvS..11a0101M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhRvS..11a0101M">Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T. F. 2008-01-01 Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25a2106L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25a2106L">Effects of finite electron temperature on gradient drift instabilities in partially magnetized plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lakhin, V. P.; Ilgisonis, V. I.; Smolyakov, A. I.; Sorokina, E. A.; Marusov, N. A. 2018-01-01 The gradient-drift instabilities of partially magnetized plasmas in plasma devices with crossed electric and magnetic fields are investigated in the framework of the two-fluid model with finite electron temperature in an inhomogeneous magnetic field. The finite electron Larmor radius (FLR) effects are also included via the gyroviscosity tensor taking into account the magnetic field gradient. This model correctly describes the electron dynamics for k⊥ρe>1 in the sense of Padé approximants (here, k⊥ and ρe are the wavenumber perpendicular to the magnetic field and the electron Larmor radius, respectively). The local dispersion relation for electrostatic plasma perturbations with the frequency in the range between the ion and electron cyclotron frequencies and propagating strictly perpendicular to the magnetic field is derived. The dispersion relation includes the effects of the equilibrium E ×B electron current, finite ion velocity, electron inertia, electron FLR, magnetic field gradients, and Debye length effects. The necessary and sufficient condition of stability is derived, and the stability boundary is found. It is shown that, in general, the electron inertia and FLR effects stabilize the short-wavelength perturbations. In some cases, such effects completely suppress the high-frequency short-wavelength modes so that only the long-wavelength low-frequency (with respect to the lower-hybrid frequency) modes remain unstable. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013233','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013233">Self-Nulling Lock-in Detection Electronics for Capacitance Probe Electrometer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Blaes, Brent R.; Schaefer, Rembrandt T. 2012-01-01 A multi-channel electrometer voltmeter that employs self-nulling lock-in detection electronics in conjunction with a mechanical resonator with noncontact voltage sensing electrodes has been developed for space-based measurement of an Internal Electrostatic Discharge Monitor (IESDM). The IESDM is new sensor technology targeted for integration into a Space Environmental Monitor (SEM) subsystem used for the characterization and monitoring of deep dielectric charging on spacecraft. Use of an AC-coupled lock-in amplifier with closed-loop sense-signal nulling via generation of an active guard-driving feedback voltage provides the resolution, accuracy, linearity and stability needed for long-term space-based measurement of the IESDM. This implementation relies on adjusting the feedback voltage to drive the sense current received from the resonator s variable-capacitance-probe voltage transducer to approximately zero, as limited by the signal-to-noise performance of the loop electronics. The magnitude of the sense current is proportional to the difference between the input voltage being measured and the feedback voltage, which matches the input voltage when the sense current is zero. High signal-to-noise-ratio (SNR) is achieved by synchronous detection of the sense signal using the correlated reference signal derived from the oscillator circuit that drives the mechanical resonator. The magnitude of the feedback voltage, while the loop is in a settled state with essentially zero sense current, is an accurate estimate of the input voltage being measured. This technique has many beneficial attributes including immunity to drift, high linearity, high SNR from synchronous detection of a single-frequency carrier selected to avoid potentially noisy 1/f low-frequency spectrum of the signal-chain electronics, and high accuracy provided through the benefits of a driven shield encasing the capacitance- probe transducer and guarded input triaxial lead-in. Measurements obtained from a 2- channel prototype electrometer have demonstrated good accuracy (|error| < 0.2 V) and high stability. Twenty-four-hour tests have been performed with virtually no drift. Additionally, 5,500 repeated one-second measurements of 100 V input were shown to be approximately normally distributed with a standard deviation of 140 mV. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24713100','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24713100">In situ observation of electron beam-induced phase transformation of CaCO3 to CaO via ELNES at low electron beam energies.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Golla-Schindler, Ute; Benner, Gerd; Orchowski, Alexander; Kaiser, Ute 2014-06-01 It is demonstrated that energy-filtered transmission electron microscope enables following of in situ changes of the Ca-L2,3 edge which can originate from variations in both local symmetry and bond lengths. Low accelerating voltages of 20 and 40 kV slow down radiation damage effects and enable study of the start and finish of phase transformations. We observed electron beam-induced phase transformation of single crystalline calcite (CaCO3) to polycrystalline calcium oxide (CaO) which occurs in different stages. The coordination of Ca in calcite is close to an octahedral one streched along the <111> direction. Changes during phase transformation to an octahedral coordination of Ca in CaO go along with a bond length increase by 5 pm, where oxygen is preserved as a binding partner. Electron loss near-edge structure of the Ca-L2,3 edge show four separated peaks, which all shift toward lower energies during phase transformation at the same time the energy level splitting increases. We suggest that these changes can be mainly addressed to the change of the bond length on the order of picometers. An important pre-condition for such studies is stability of the energy drift in the range of meV over at least 1 h, which is achieved with the sub-Ångström low-voltage transmission electron microscope I prototype microscope. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985GeoRL..12..457W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985GeoRL..12..457W">ELF wave production by an electron beam emitting rocket system and its suppression on auroral field lines - Evidence for Alfven and drift waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Winckler, J. R.; Erickson, K. N.; Abe, Y.; Steffen, J. E.; Malcolm, P. R. 1985-07-01 Orthogonal probes on a free-flying plasma diagnostics payload are used to study ELF electric disturbances in the auroral ionosphere that are due to the injection of powerful electron beams. Frequency spectrograms are presented for various pitch angles, pulsing characteristics, and other properties of the injected beams; the large scale DC ionospheric convection electric field is measured, together with auroral particle precipitation, visual auroral forms, and ionospheric parameters. In view of the experimental results obtained, it is postulated that the observed ELF waves are in the Alfven and drift modes, and are generated by the positive vehicle potential during beam injection. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800030860&hterms=lemons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlemons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800030860&hterms=lemons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlemons">A possible closure relation for heat transport in the solar wind</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Feldman, W. C.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.; Lemons, D. S. 1979-01-01 The objective of the present paper is to search for an empirical closure relation for solar wind heat transport that applies to a microscopic scale. This task is approached by using the quasi-linear wave-particle formalism proposed by Perkins (1973) as a guide to derive an equation relating the relative drift speed between core-electron and proton populations to local bulk flow conditions. The resulting relationship, containing one free parameter, is found to provide a good characterization of Los Alamos Imp electron data measuring during the period from March 1971 through August 1974. An empirical closure relation is implied by this result because of the observed proportionality between heat flux and relative drift speed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P11B2514M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P11B2514M">Magnetically Controlled Upper Ionosphere of Mars</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Majeed, T.; Al Aryani, O.; Al Mutawa, S.; Bougher, S. W.; Haider, S. A. 2017-12-01 The electron density (Ne) profiles measured by the Mars Express spacecraft over regions of strong crustal magnetic fields have shown anomalous characteristics of the topside plasma distribution with variable scale heights. One of such Ne profiles is located at 82oS and 180oE whose topside ionosphere is extended up to an altitude of 700 km. The crustal magnetic field at this southern site is nearly vertical and open to the access of solar wind plasma through magnetic reconnection with the interplanetary magnetic field. This can lead to the acceleration of electrons and ions during the daytime ionosphere. The downward accelerated electrons with energies >200 eV can penetrate deep into the Martian upper ionosphere along vertical magnetic field lines and cause heating, excitation and ionization of the background atmosphere. The upward acceleration of ions resulting from energy input by precipitating electrons can lead to enhance ion escape rate and modify scale heights of the topside ionosphere. We have developed a 1-D chemical diffusive model from 100 km to 400 km to interpret the Martian ionospheric structure at 82oS latitude. The primary source of ionization in the model is due to solar EUV radiation. An extra ionization source due to precipitating electrons of 0.25 keV, peaking near an altitude of 145 km is added in the model to reasonably reproduce the measured ionospheric structure below an altitude of 180 km. The behavior of the topside ionosphere can be interpreted by the vertical plasma transport caused by precipitating electrons. The vertical transport of plasma in our model is simulated by vertical ion velocities, whose values can be interpreted as drift velocities along magnetic field lines. We find that the variation of the topside Ne scale heights is sensitive to the magnitudes of upward and downward drifts with an imposed outward flux boundary condition at the top of the model. The model requires an upward flux of more than 107 ions cm-2 s-1 for both O2+ and O+, and drift speeds of 200 m/s to interpret the measured topside ionospheric structure for altitudes >180 km. The magnitudes of outward ion fluxes and drift velocities are compared with those simulated by existing models. The model results will be presented in comparison with the measured electron density profile. This work is supported by MBRSC, Dubai, UAE. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3039454','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3039454">Model error in covariance structure models: Some implications for power and Type I error</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Coffman, Donna L. 2010-01-01 The present study investigated the degree to which violation of the parameter drift assumption affects the Type I error rate for the test of close fit and power analysis procedures proposed by MacCallum, Browne, and Sugawara (1996) for both the test of close fit and the test of exact fit. The parameter drift assumption states that as sample size increases both sampling error and model error (i.e. the degree to which the model is an approximation in the population) decrease. Model error was introduced using a procedure proposed by Cudeck and Browne (1992). The empirical power for both the test of close fit, in which the null hypothesis specifies that the Root Mean Square Error of Approximation (RMSEA) ≤ .05, and the test of exact fit, in which the null hypothesis specifies that RMSEA = 0, is compared with the theoretical power computed using the MacCallum et al. (1996) procedure. The empirical power and theoretical power for both the test of close fit and the test of exact fit are nearly identical under violations of the assumption. The results also indicated that the test of close fit maintains the nominal Type I error rate under violations of the assumption. PMID:21331302 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...820...62W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...820...62W">Nonrelativistic Perpendicular Shocks Modeling Young Supernova Remnants: Nonstationary Dynamics and Particle Acceleration at Forward and Reverse Shocks</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wieland, Volkmar; Pohl, Martin; Niemiec, Jacek; Rafighi, Iman; Nishikawa, Ken-Ichi 2016-03-01 For parameters that are applicable to the conditions at young supernova remnants, we present results of two-dimensional, three-vector (2D3V) particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at a 45^\\circ angle to the simulation plane to approximate three-dimensional (3D) physics. We developed an improved clean setup that uses the collision of two plasma slabs with different densities and velocities, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations due to shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales produced by the gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but is commensurate with {\\boldsymbol{E}}× {\\boldsymbol{B}} drift. We observe a stable supra-thermal tail in the ion spectra, but no electron acceleration because the amplitude of the Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other two-dimensional (2D) simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but the pre-acceleration efficacy might be reduced with respect to the 2D results once 3D effects are fully accounted for. Other microphysical factors may also play a part in limiting the amplitude of the Buneman waves or preventing the return of electrons to the foot region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1227724-nonthermally-dominated-electron-acceleration-during-magnetic-reconnection-low-plasma','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1227724-nonthermally-dominated-electron-acceleration-during-magnetic-reconnection-low-plasma">Nonthermally dominated electron acceleration during magnetic reconnection in a low- β plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Li, Xiaocan; Guo, Fan; Li, Hui; ... 2015-09-24 By means of fully kinetic simulations, we investigate electron acceleration during magnetic reconnection in a nonrelativistic proton–electron plasma with conditions similar to solar corona and flares. We demonstrate that reconnection leads to a nonthermally dominated electron acceleration with a power-law energy distribution in the nonrelativistic low-β regime but not in the high-β regime, where β is the ratio of the plasma thermal pressure and the magnetic pressure. The accelerated electrons contain most of the dissipated magnetic energy in the low-β regime. A guiding-center current description is used to reveal the role of electron drift motions during the bulk nonthermal energization.more » We find that the main acceleration mechanism is a Fermi-type acceleration accomplished by the particle curvature drift motion along the electric field induced by the reconnection outflows. Although the acceleration mechanism is similar for different plasma β, low-β reconnection drives fast acceleration on Alfvénic timescales and develops power laws out of thermal distribution. Thus, the nonthermally dominated acceleration resulting from magnetic reconnection in low-β plasma may have strong implications for the highly efficient electron acceleration in solar flares and other astrophysical systems.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23297706','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23297706">Sea lice levels on wild Atlantic salmon, Salmo salar L., returning to the coast of Ireland.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Jackson, D; Kane, F; O'Donohoe, P; Mc Dermott, T; Kelly, S; Drumm, A; Newell, J 2013-03-01 The sea lice population structure, prevalence and intensity of Lepeophtheirus salmonis have been studied over a period extending from 2004 to 2011. Infestation data were collected from the interceptor drift net fishery from 2004 until it was closed in 2006. From 2010, data were collected from the inshore draft net fishery. In all, 34 samples from the drift and draft net fisheries have been analysed to date. Prevalence of infestation with L. salmonis regularly approached 100% in samples of hosts recovered from the offshore drift net fishery. Abundance was variable both within and between years with a maximum mean abundance of 25.8 lice per fish recorded in 2004. The population structure of L. salmonis on hosts recovered in the inshore and estuarine draft net fisheries was different from that observed in the more offshore drift net samples. There is clear evidence of recent infestation with L. salmonis in the draft net samples. © 2013 Blackwell Publishing Ltd. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPTP2079M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPTP2079M">Drift effects on the tokamak power scrape-off width</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Meier, E. T.; Goldston, R. J.; Kaveeva, E. G.; Mordijck, S.; Rozhansky, V. A.; Senichenkov, I. Yu.; Voskoboynikov, S. P. 2015-11-01 Recent experimental analysis suggests that the scrape-off layer (SOL) heat flux width (λq) for ITER will be near 1 mm, sharply narrowing the planned operating window. In this work, motivated by the heuristic drift (HD) model, which predicts the observed inverse plasma current scaling, SOLPS-ITER is used to explore drift effects on λq. Modeling focuses on an H-mode DIII-D discharge. In initial results, target recycling is set to 90%, resulting in sheath-limited SOL conditions. SOL particle diffusivity (DSOL) is varied from 0.1 to 1 m2/s. When drifts are included, λq is insensitive to DSOL, consistent with the HD model, with λq near 3 mm; in no-drift cases, λq varies from 2 to 5 mm. Drift effects depress near-separatrix potential, generating a channel of strong electron heat convection that is insensitive to DSOL. Sensitivities to thermal diffusivities, plasma current, toroidal magnetic field, and device size are also assessed. These initial results will be discussed in detail, and progress toward modeling experimentally relevant high-recycling conditions will be reported. Supported by U.S. DOE Contract DE-SC0010434. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18653925','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18653925">On the sources of drift in a turbine-based spirometer.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Ha, Jonathan K; Perlow, Daniel B; Yi, Byong Yong; Yu, Cedric X 2008-08-21 A systematic study on the sources of drift in a turbine-based spirometer (VMM-400) is presented. The study utilized an air-tight cylinder to pump air through the spirometer in a precise and programmable manner. Factors contributing to the drift were isolated and quantified. The drift due to imbalance in the electronics and the mechanical blade increased from 1% per breathing cycle to as much as 10% when the flow rate decreased from 0.24 to 0.08 l s(-1). A temperature difference of 16 degrees between the ambient and the air in the cylinder contributed about 3.5%. Most significantly, a difference in the breathing between inhalation and exhalation could produce a drift of 40% per breathing cycle, or even higher, depending on the extent of the breathing asymmetry. The origin of this drift was found to be rooted in the differential response of the spirometer to the different flow rate. Some ideas and suggestions for a correction strategy are provided for future work. The present work provides an important first step for eventual utilization of a spirometer as a stand-alone breathing surrogate for gating or tracking radiation therapy. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..GECMW6044A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..GECMW6044A">Azimuthal ExB drift of electrons induced by the radial electric field flowing through a longitudinal magnetic channel with non-magnetized ions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Akatsuka, Hiroshi; Takeda, Jun; Nezu, Atsushi 2016-09-01 To examine of the effect of the radial electric field on the azimuthal electron motion under E × B field for plasmas with magnetized electrons and non-magnetized ions, an experimental study is conducted by a stationary plasma flow. The argon plasma flow is generated by a DC arc generator under atmospheric pressure, followed by a cw expansion into a rarefied gas-wind tunnel with a uniform magnetic field 0 . 16 T. Inside one of the magnets, we set a ring electrode to apply the radial electric field. We applied an up-down probe for the analysis of the electron motion, where one of the tips is also used as a Langmuir probe to measure electron temperature, density and the space potential. We found that the order of the radial electric field is about several hundred V/m, which should be caused by the difference in the magnetization between electrons and ions. Electron saturation current indicates the existence of the E × B rotation of electrons, whose order is about 2000 - 4000 m/s. The order of the observed electron drift velocity is consistent with the theoretical value calculated from the applied magnetic field and the measured electric field deduced from the space potential. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..GECJW4004L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..GECJW4004L">Theory for the anomalous electron transport in Hall-effect thrusters</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lafleur, Trevor; Baalrud, Scott; Chabert, Pascal 2016-09-01 Using insights from particle-in-cell (PIC) simulations, we develop a kinetic theory to explain the anomalous cross-field electron transport in Hall-effect thrusters (HETs). The large axial electric field in the acceleration region of HETs, together with the radially applied magnetic field, causes electrons to drift in the azimuthal direction with a very high velocity. This drives an electron cyclotron instability that produces large amplitude oscillations in the plasma density and azimuthal electric field, and which is convected downstream due to the large axial ion drift velocity. The frequency and wavelength of the instability are of the order of 5 MHz and 1 mm respectively, while the electric field amplitude can be of a similar magnitude to axial electric field itself. The instability leads to enhanced electron scattering many orders of magnitude higher than that from standard electron-neutral or electron-ion Coulomb collisions, and gives electron mobilities in good agreement with experiment. Since the instability is a strong function of almost all plasma properties, the mobility cannot in general be fitted with simple 1/B or 1/B2 scaling laws, and changes to the secondary electron emission coefficient of the HET channel walls are expected to play a role in the evolution of the instability. This work received financial support from a CNES postdoctoral research award. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SoPh..293...62K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SoPh..293...62K">Oscillations and Waves in Radio Source of Drifting Pulsation Structures</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Karlický, Marian; Rybák, Ján; Bárta, Miroslav 2018-04-01 Drifting pulsation structures (DPSs) are considered to be radio signatures of the plasmoids formed during magnetic reconnection in the impulsive phase of solar flares. In the present paper we analyze oscillations and waves in seven examples of drifting pulsation structures, observed by the 800 - 2000 MHz Ondřejov Radiospectrograph. For their analysis we use a new type of oscillation maps, which give us much more information as regards processes in DPSs than that in previous analyses. Based on these oscillation maps, made from radio spectra by the wavelet technique, we recognized quasi-periodic oscillations with periods ranging from about 1 to 108 s in all studied DPSs. This strongly supports the idea that DPSs are generated during a fragmented magnetic reconnection. Phases of most the oscillations in DPSs, especially for the period around 1 s, are synchronized ("infinite" frequency drift) in the whole frequency range of DPSs. For longer periods in some DPSs we found that the phases of the oscillations drift with the frequency drift in the interval from -17 to +287 MHz s^{-1}. We propose that these drifting phases can be caused (a) by the fast or slow magnetosonic waves generated during the magnetic reconnection and propagating through the plasmoid, (b) by a quasi-periodic structure in the plasma inflowing to the reconnection forming a plasmoid, and (c) by a quasi-periodically varying reconnection rate in the X-point of the reconnection close to the plasmoid. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/4199645','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4199645">ION ACCELERATOR</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Bell, J.S. 1959-09-15 An arrangement for the drift tubes in a linear accelerator is described whereby each drift tube acts to shield the particles from the influence of the accelerating field and focuses the particles passing through the tube. In one embodiment the drift tube is splii longitudinally into quadrants supported along the axis of the accelerator by webs from a yoke, the quadrants. webs, and yoke being of magnetic material. A magnetic focusing action is produced by energizing a winding on each web to set up a magnetic field between adjacent quadrants. In the other embodiment the quadrants are electrically insulated from each other and have opposite polarity voltages on adjacent quadrants to provide an electric focusing fleld for the particles, with the quadrants spaced sufficienily close enough to shield the particles within the tube from the accelerating electric field. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5618938','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5618938">Age-related epigenetic drift and phenotypic plasticity loss: implications in prevention of age-related human diseases</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Li, Yuanyuan; Tollefsbol, Trygve O 2016-01-01 Aging is considered as one of the most important developmental processes in organisms and is closely associated with global deteriorations of epigenetic markers such as aberrant methylomic patterns. This altered epigenomic state, referred to ‘epigenetic drift’, reflects deficient maintenance of epigenetic marks and contributes to impaired cellular and molecular functions in aged cells. Epigenetic drift-induced abnormal changes during aging are scantily repaired by epigenetic modulators. This inflexibility in the aged epigenome may lead to an age-related decline in phenotypic plasticity at the cellular and molecular levels due to epigenetic drift. This perspective aims to provide novel concepts for understanding epigenetic effects on the aging process and to provide insights into epigenetic prevention and therapeutic strategies for age-related human disease. PMID:27882781 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1047876','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1047876">Modeling and Simulation for Particle Radiation Damage to Electronic and Opto-Electronic Devices</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2018-01-25 AFRL-RV-PS- AFRL-RV-PS- TR-2018-0001 TR-2018-0001 MODELING & SIMULATION FOR PARTICLE RADIATION DAMAGE TO ELECTRONIC AND OPTO- ELECTRONIC DEVICES... Electronic and Opto- Electronic Devices 5a. CONTRACT NUMBER FA9453-14-1-0248 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6. AUTHOR(S) Sanjay...nBp Diode Assuming the light is incident on the n-side of the photodiode, the drift-diffusion equation for the minority electron of the p-type </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSA13C4018C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSA13C4018C">On the Longitudinal Morphology of Zonal Irregularity Drift Measured using Networks of GPS Scintillation Monitors</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Carrano, C. S.; Groves, K. M.; Valladares, C. E.; Delay, S. H. 2014-12-01 A complete characterization of field-aligned ionospheric irregularities responsible for the scintillation of satellite signals includes not only their spectral properties (power spectral strength, spectral index, anisotropy ratio, and outer-scale) but also their horizontal drift velocity. From a system impacts perspective, the horizontal drift velocity is important in that it dictates the rate of signal fading and also, to an extent, the level of phase fluctuations encountered by the receiver. From a physics perspective, studying the longitudinal morphology of zonal irregularity may lead to an improved understanding of the F region dynamo and regional electrodynamics at low latitudes. The irregularity drift at low latitudes is predominantly zonal and is most commonly measured by cross-correlating observations of satellite signals made by a pair of closely-spaced antennas. The AFRL-SCINDA network operates a small number of VHF spaced-antenna systems at low latitude stations for this purpose. A far greater number of GPS scintillation monitors are operated by AFRL-SCINDA (25-30) and the Low Latitude Ionospheric Sensor Network (35-50), but the receivers are situated too far apart to monitor the drift using cross-correlation techniques. In this paper, we present an alternative approach that leverages the weak scatter scintillation theory (Rino, Radio Sci., 1979) to infer the zonal irregularity drift from single-station GPS measurements of S4, sigma-phi, and the propagation geometry alone. Unlike the spaced-receiver technique, this technique requires assumptions for the height of the scattering layer (which introduces a bias in the drift estimates) and the spectral index of the irregularities (which affects the spread of the drift estimates about the mean). Nevertheless, theory and experiment show that the ratio of sigma-phi to S4 is less sensitive to these parameters than it is to the zonal drift, and hence the zonal drift can be estimated with reasonable accuracy. In this talk, we first validate the technique using spaced VHF-antenna measurements of zonal irregularity drift from the AFRL-SCINDA network. Next, we discuss preliminary results from our investigation into the longitudinal morphology of zonal irregularity drift using the AFRL-SCINDA and LISN networks of GPS scintillation monitors. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active">17</li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active">18</li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1412760','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1412760"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Seletskiy, S.; De Monte, V.; Di Lieto, A. In the LEReC Cooling Section (CS) the RHIC ions are traveling together with and getting cooled by the LEReC electrons. The required cooling rate sets the limit of 150 urad on tolerable angles of the electrons in the CS. One of the components of overall electron angle is the angle of the e-beam trajectory with respect to the ion beam trajectory. We set the limit for electron trajectory angle to 100 urad. It is critical for preserving small trajectory angle to keep the transverse magnetic field inside the CS drifts within +/- 2.3 mG. The drifts in the CS mustmore » be shielded from the ambient magnetic fields of the RHIC tunnel, which can be as high as 0.5 G, to minimize the transverse field inside the CS vacuum chamber. In this paper we present the final design of the magnetic shielding of the LEReC CS and discuss the results of tests dedicated to studies of the shielding effectiveness.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/935734-performance-commercial-silicon-drift-detector-ray-microanalysis','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/935734-performance-commercial-silicon-drift-detector-ray-microanalysis">Performance of a Commercial Silicon Drift Detector for X-ray Microanalysis</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kenik, Edward A 2008-01-01 Silicon drift detectors (SDDs) are rapidly becoming the energy dispersive spectrometer of choice especially for scanning electron microscopy applications. The complementary features of large active areas (i.e., collection angle) and high count rate capability of these detector contribute to their popularity, as well as the absence of liquid nitrogen cooling of the detector. The performance of an EDAX Apollo 40 SDD on a JEOL 6500F SEM will be discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/20795839-electron-beam-charging-insulators-self-consistent-flight-drift-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/20795839-electron-beam-charging-insulators-self-consistent-flight-drift-model">Electron beam charging of insulators: A self-consistent flight-drift model</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Touzin, M.; Goeuriot, D.; Guerret-Piecourt, C. 2006-06-01 Electron beam irradiation and the self-consistent charge transport in bulk insulating samples are described by means of a new flight-drift model and an iterative computer simulation. Ballistic secondary electron and hole transport is followed by electron and hole drifts, their possible recombination and/or trapping in shallow and deep traps. The trap capture cross sections are the Poole-Frenkel-type temperature and field dependent. As a main result the spatial distributions of currents j(x,t), charges {rho}(x,t), the field F(x,t), and the potential slope V(x,t) are obtained in a self-consistent procedure as well as the time-dependent secondary electron emission rate {sigma}(t) and the surfacemore » potential V{sub 0}(t). For bulk insulating samples the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and {sigma}=1. Especially for low electron beam energies E{sub 0}<4 keV the incorporation of mainly positive charges can be controlled by the potential V{sub G} of a vacuum grid in front of the target surface. For high beam energies E{sub 0}=10, 20, and 30 keV high negative surface potentials V{sub 0}=-4, -14, and -24 kV are obtained, respectively. Besides open nonconductive samples also positive ion-covered samples and targets with a conducting and grounded layer (metal or carbon) on the surface have been considered as used in environmental scanning electron microscopy and common SEM in order to prevent charging. Indeed, the potential distributions V(x) are considerably small in magnitude and do not affect the incident electron beam neither by retarding field effects in front of the surface nor within the bulk insulating sample. Thus the spatial scattering and excitation distributions are almost not affected.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJD...68..220M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJD...68..220M">A Multi Water Bag model of drift kinetic electron plasmaa</xref></a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Morel, Pierre; Ghiro, Florent Dreydemy; Berionni, Vincent; Coulette, David; Besse, Nicolas; Gürcan, Özgür D. 2014-08-01 A Multi Water Bag model is proposed for describing drift kinetic plasmas in a magnetized cylindrical geometry, relevant for various experimental devices, solar wind modeling... The Multi Water Bag (MWB) model is adapted to the description of a plasma with kinetic electrons as well as an arbitrary number of kinetic ions. This allows to describe the kinetic dynamics of the electrons, making possible the study of electron temperature gradient (ETG) modes, in addition to the effects of non adiabatic electrons on the ion temperature gradient (ITG) modes, that are of prime importance in the magnetized plasmas micro-turbulence [X. Garbet, Y. Idomura, L. Villard, T.H. Watanabe, Nucl. Fusion 50, 043002 (2010); J.A. Krommes, Ann. Rev. Fluid Mech. 44, 175 (2012)]. The MWB model is shown to link kinetic and fluid descriptions, depending on the number of bags considered. Linear stability of the ETG modes is presented and compared to the existing results regarding cylindrical ITG modes [P. Morel, E. Gravier, N. Besse, R. Klein, A. Ghizzo, P. Bertrand, W. Garbet, Ph. Ghendrih, V. Grandgirard, Y. Sarazin, Phys. Plasmas 14, 112109 (2007)]. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820014565','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820014565">Three-dimensional relativistic field-electron interaction in a multicavity high-power klystron. 1: Basic theory</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kosmahl, H. G. 1982-01-01 A theoretical investigation of three dimensional relativistic klystron action is described. The relativistic axisymmetric equations of motion are derived from the time-dependent Lagrangian function for a charged particle in electromagnetic fields. An analytical expression of the fringing RF electric and magnetic fields within and in the vicinity of the interaction gap and the space-charge forces between axially and radially elastic deformable rings of charges are both included in the formulation. This makes an accurate computation of electron motion through the tunnel of the cavities and the drift tube spaces possible. Method of analysis is based on Lagrangian formulation. Bunching is computed using a disk model of electron stream in which the electron stream is divided into axisymmetric disks of equal charge and each disk is assumed to consist of a number of concentric rings of equal charges. The Individual representative groups of electrons are followed through the interaction gaps and drift tube spaces. Induced currents and voltages in interacting cavities are calculated by invoking the Shockley-Ramo theorem. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSM22B..02K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSM22B..02K">Radiation Belt Transport Driven by Solar Wind Dynamic Pressure Fluctuations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kress, B. T.; Hudson, M. K.; Ukhorskiy, A. Y.; Mueller, H. 2012-12-01 The creation of the Earth's outer zone radiation belts is attributed to earthward transport and adiabatic acceleration of electrons by drift-resonant interactions with electromagnetic fluctuations in the magnetosphere. Three types of radial transport driven by solar wind dynamic pressure fluctuations that have been identified are: (1) radial diffusion [Falthammer, 1965], (2) significant changes in the phase space density radial profile due to a single or few ULF drift-resonant interactions [Ukhorskiy et al., 2006; Degeling et al., 2008], and (3) shock associated injections of radiation belt electrons occurring in less than a drift period [Li et al., 1993]. A progress report will be given on work to fully characterize different forms of radial transport and their effect on the Earth's radiation belts. The work is being carried out by computing test-particle trajectories in electric and magnetic fields from a simple analytic ULF field model and from global MHD simulations of the magnetosphere. Degeling, A. W., L. G. Ozeke, R. Rankin, I. R. Mann, and K. Kabin (2008), Drift resonant generation of peaked relativistic electron distributions by Pc 5 ULF waves, textit{J. Geophys. Res., 113}, A02208, doi:10.1029/2007JA012411. Fälthammar, C.-G. (1965), Effects of Time-Dependent Electric Fields on Geomagnetically Trapped Radiation, J. Geophys. Res., 70(11), 2503-2516, doi:10.1029/JZ070i011p02503. Li, X., I. Roth, M. Temerin, J. R. Wygant, M. K. Hudson, and J. B. Blake (1993), Simulation of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC, textit{Geophys. Res. Lett., 20}(22), 2423-2426, doi:10.1029/93GL02701. Ukhorskiy, A. Y., B. J. Anderson, K. Takahashi, and N. A. Tsyganenko (2006), Impact of ULF oscillations in solar wind dynamic pressure on the outer radiation belt electrons, textit{Geophys. Res. Lett., 33}(6), L06111, doi:10.1029/2005GL024380. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvB..92e4201G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvB..92e4201G">Microscopic origin of resistance drift in the amorphous state of the phase-change compound GeTe</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gabardi, S.; Caravati, S.; Sosso, G. C.; Behler, J.; Bernasconi, M. 2015-08-01 Aging is a common feature of the glassy state. In the case of phase-change chalcogenide alloys the aging of the amorphous state is responsible for an increase of the electrical resistance with time. This phenomenon called drift is detrimental in the application of these materials in phase-change nonvolatile memories, which are emerging as promising candidates for storage class memories. By means of combined molecular dynamics and electronic structure calculations based on density functional theory, we have unraveled the atomistic origin of the resistance drift in the prototypical phase-change compound GeTe. The drift results from a widening of the band gap and a reduction of Urbach tails due to structural relaxations leading to the removal of chains of Ge-Ge homopolar bonds. The same structural features are actually responsible for the high mobility above the glass transition which boosts the crystallization speed exploited in the device. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22614131-analytical-numerical-treatment-resistive-drift-instability-plasma-slab','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22614131-analytical-numerical-treatment-resistive-drift-instability-plasma-slab">Analytical and numerical treatment of resistive drift instability in a plasma slab</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Mirnov, V. V., E-mail: vvmirnov@wisc.edu; Sauppe, J. P.; Hegna, C. C. An analytic approach combining the effect of equilibrium diamagnetic flows and the finite ionsound gyroradius associated with electron−ion decoupling and kinetic Alfvén wave dispersion is derived to study resistive drift instabilities in a plasma slab. Linear numerical computations using the NIMROD code are performed with cold ions and hot electrons in a plasma slab with a doubly periodic box bounded by two perfectly conducting walls. A linearly unstable resistive drift mode is observed in computations with a growth rate that is consistent with the analytic dispersion relation. The resistive drift mode is expected to be suppressed by magnetic shear inmore » unbounded domains, but the mode is observed in numerical computations with and without magnetic shear. In the slab model, the finite slab thickness and the perfectly conducting boundary conditions are likely to account for the lack of suppression.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22494537-hough-transform-method-track-finding-center-drift-chamber','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22494537-hough-transform-method-track-finding-center-drift-chamber">Hough transform method for track finding in center drift chamber</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Azmi, K. A. Mohammad Kamal, E-mail: khasmidatul@siswa.um.edu.my; Wan Abdullah, W. A. T., E-mail: wat@um.edu.my; Ibrahim, Zainol Abidin Hough transform is a global tracking method used which had been expected to be faster approach for tracking the circular pattern of electron moving in Center Drift Chamber (CDC), by transforming the point of hit into a circular curve. This paper present the implementation of hough transform method for the reconstruction of tracks in Center Drift Chamber (CDC) which have been generated by random number in C language programming. Result from implementation of this method shows higher peak of circle parameter value (xc,yc,rc) that indicate the similarity value of the parameter needed for circular track in CDC for charged particlesmore » in the region of CDC.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45..556L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45..556L">Electron Jet Detected by MMS at Dipolarization Front</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Liu, C. M.; Fu, H. S.; Vaivads, A.; Khotyaintsev, Y. V.; Gershman, D. J.; Hwang, K.-J.; Chen, Z. Z.; Cao, D.; Xu, Y.; Yang, J.; Peng, F. Z.; Huang, S. Y.; Burch, J. L.; Giles, B. L.; Ergun, R. E.; Russell, C. T.; Lindqvist, P.-A.; Le Contel, O. 2018-01-01 Using MMS high-resolution measurements, we present the first observation of fast electron jet (<fi>V</fi><fi>e</fi> 2,000 km/s) at a dipolarization front (DF) in the magnetotail plasma sheet. This jet, with scale comparable to the DF thickness ( 0.9 <fi>d</fi><fi>i</fi>), is primarily in the tangential plane to the DF current sheet and mainly undergoes the E × B drift motion; it contributes significantly to the current system at the DF, including a localized ring-current that can modify the DF topology. Associated with this fast jet, we observed a persistent normal electric field, strong lower hybrid drift waves, and strong energy conversion at the DF. Such strong energy conversion is primarily attributed to the electron-jet-driven current (E ṡ j<fi>e</fi> ≈ 2 E ṡ j<fi>i</fi>), rather than the ion current suggested in previous studies. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvD..97i2007A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvD..97i2007A">Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Grandi, L.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Howlett, J.; Itay, R.; Kaminsky, B.; Kazama, S.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Lin, Q.; Lindemann, S.; Lindner, M.; Lombardi, F.; Lopes, J. A. M.; Mahlstedt, J.; Manfredini, A.; Maris, I.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Messina, M.; Micheneau, K.; Molinario, A.; Morâ, K.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Pizzella, V.; Piro, M.-C.; Plante, G.; Priel, N.; Ramírez García, D.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rupp, N.; Saldanha, R.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Shockley, E.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Vargas, M.; Wang, H.; Wang, Z.; Wei, Y.; Weinheimer, C.; Wittweg, C.; Wulf, J.; Ye, J.; Zhang, Y.; Zhu, T.; Xenon Collaboration 2018-05-01 We report on the response of liquid xenon to low energy electronic recoils below 15 keV from beta decays of tritium at drift fields of 92 V /cm , 154 V /cm and 366 V /cm using the XENON100 detector. A data-to-simulation fitting method based on Markov Chain Monte Carlo is used to extract the photon yields and recombination fluctuations from the experimental data. The photon yields measured at the two lower fields are in agreement with those from literature; additional measurements at a higher field of 366 V /cm are presented. The electronic and nuclear recoil discrimination as well as its dependence on the drift field and photon detection efficiency are investigated at these low energies. The results provide new measurements in the energy region of interest for dark matter searches using liquid xenon. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110013459','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110013459">Saturn Neutron Exosphere as Source for Inner and Innermost Radiation Belts</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cooper, John; Lipatov, Alexander; Sittler, Edward; Sturner, Steven 2011-01-01 Energetic proton and electron measurements by the ongoing Cassini orbiter mission are expanding our knowledge of the highest energy components of the Saturn magnetosphere in the inner radiation belt region after the initial discoveries of these belts by the Pioneer 11 and Voyager 2 missions. Saturn has a neutron exosphere that extends throughout the magnetosphere from the cosmic ray albedo neutron source at the planetary main rings and atmosphere. The neutrons emitted from these sources at energies respectively above 4 and 8 eV escape the Saturn system, while those at lower energies are gravitationally bound. The neutrons undergo beta decay in average times of about 1000 seconds to provide distributed sources of protons and electrons throughout Saturn's magnetosphere with highest injection rates close to the Saturn and ring sources. The competing radiation belt source for energetic electrons is rapid inward diffusion and acceleration of electrons from the middle magnetosphere and beyond. Minimal losses during diffusive transport across the moon orbits, e.g. of Mimas and Enceladus, and local time asymmetries in electron intensity, suggest that drift resonance effects preferentially boost the diffusion rates of electrons from both sources. Energy dependences of longitudinal gradient-curvature drift speeds relative to the icy moons are likely responsible for hemispheric differences (e.g., Mimas, Tethys) in composition and thermal properties as at least partly produced by radiolytic processes. A continuing mystery is the similar radial profiles of lower energy (<10 MeV) protons in the inner belt region. Either the source of these lower energy protons is also neutron decay, but perhaps alternatively from atmospheric albedo, or else all protons from diverse distributed sources are similarly affected by losses at the moon' orbits, e.g. because the proton diffusion rates are extremely low. Enceladus cryovolcanism, and radiolytic processing elsewhere on the icy moon and ring surfaces, are additional sources of protons via ionization and charge exchange from breakup of water molecules. But one must then account somehow for local acceleration to the observed keV-MeV energies, since moon sweeping and E-ring absorption would remove protons diffusing inward from the middle magnetosphere. Although the main rings block further inward diffusion from the inner radiation belts, the exospheric neutron-decay source, combined with much slower diffusion of protons relative to electrons, may produce an innermost radiation belt in the gap between the upper atmosphere and the D-ring. This innermost belt will first be explored in-situ during the final proximal orbits of the Cassini mission. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25f1202L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25f1202L">Anomalous electron transport in Hall-effect thrusters: Comparison between quasi-linear kinetic theory and particle-in-cell simulations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lafleur, T.; Martorelli, R.; Chabert, P.; Bourdon, A. 2018-06-01 Kinetic drift instabilities have been implicated as a possible mechanism leading to anomalous electron cross-field transport in E × B discharges, such as Hall-effect thrusters. Such instabilities, which are driven by the large disparity in electron and ion drift velocities, present a significant challenge to modelling efforts without resorting to time-consuming particle-in-cell (PIC) simulations. Here, we test aspects of quasi-linear kinetic theory with 2D PIC simulations with the aim of developing a self-consistent treatment of these instabilities. The specific quantities of interest are the instability growth rate (which determines the spatial and temporal evolution of the instability amplitude), and the instability-enhanced electron-ion friction force (which leads to "anomalous" electron transport). By using the self-consistently obtained electron distribution functions from the PIC simulations (which are in general non-Maxwellian), we find that the predictions of the quasi-linear kinetic theory are in good agreement with the simulation results. By contrast, the use of Maxwellian distributions leads to a growth rate and electron-ion friction force that is around 2-4 times higher, and consequently significantly overestimates the electron transport. A possible method for self-consistently modelling the distribution functions without requiring PIC simulations is discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170006129&hterms=plasma&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dplasma','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170006129&hterms=plasma&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dplasma">Heating and Acceleration of Solar Wind Ions by Turbulent Wave Spectrum in Inhomogeneous Expanding Plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ofman, Leon; Ozak, Nataly; Vinas, Adolfo F. 2016-01-01 Near the Sun (< 10Rs) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super- Alfvenic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22525690-solar-micro-type-iii-burst-storms-long-dipolar-magnetic-field-outer-corona','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22525690-solar-micro-type-iii-burst-storms-long-dipolar-magnetic-field-outer-corona"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Morioka, A.; Misawa, H.; Obara, T. Solar micro-type III radio bursts are elements of the so-called type III storms and are characterized by short-lived, continuous, and weak emissions. Their frequency of occurrence with respect to radiation power is quite different from that of ordinary type III bursts, suggesting that the generation process is not flare-related, but due to some recurrent acceleration processes around the active region. We examine the relationship of micro-type III radio bursts with coronal streamers. We also explore the propagation channel of bursts in the outer corona, the acceleration process, and the escape route of electron beams. It is observationally confirmed that micro-typemore » III bursts occur near the edge of coronal streamers. The magnetic field line of the escaping electron beams is tracked on the basis of the frequency drift rate of micro-type III bursts and the electron density distribution model. The results demonstrate that electron beams are trapped along closed dipolar field lines in the outer coronal region, which arise from the interface region between the active region and the coronal hole. A 22 year statistical study reveals that the apex altitude of the magnetic loop ranges from 15 to 50 R{sub S}. The distribution of the apex altitude has a sharp upper limit around 50 R{sub S} suggesting that an unknown but universal condition regulates the upper boundary of the streamer dipolar field.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM52A..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM52A..05C">Neoclassical diffusion at low L-shel</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cunningham, G.; Ripoll, J. F.; Loridan, V.; Schulz, M. 2017-12-01 At very low L-shell, the lifetime of MeV electrons is dominated by pitch-angle scattering due to Coulomb collisions with background neutrals and ions. Walt's evaluation of this lifetime explained Van Allen's observations of the decay of the radiation belts in the early 1960's, for L<1.25 but Imhof et al showed that the apparent lifetime of >500 keV electrons for L=[1.15,1.21] was much greater than predicted by Walt's model when the decay was observed over 3 years rather than just a few months. Imhof et al argued that inward radial diffusion from larger L would be a source of electrons at low L, thus increasing the apparent lifetimes that were observed, but did not speculate on the cause of such diffusion across L. Newkirk and Walt estimated the radial diffusion coefficient that would be needed to explain the apparent lifetimes observed by Imhof et al. The radial diffusion coefficients they inferred dropped sharply as L increased, contrasting with the radial diffusion coefficients that had been recently developed by Falthammar [1965], which increase as a power law in L. Newkirk and Walt noted Falthammar's speculation that pitch-angle diffusion caused by Coulomb scattering, when coupled to drift-shell splitting associated with non-dipolar terms in the near-Earth geomagnetic field, might be the physical basis for the radial diffusion, but they did not attempt to quantify this effect. Roederer et al demonstrated that Coulomb scattering plus drift-shell splitting could explain the Newkirk and Walt results but they did not perform an exhaustive study. In the field of magnetically confined fusion, the movement of charged particles to different drift-shells caused by the combination of collisions and drift-shell splitting is labeled `neoclassical' diffusion. By contrast, `anomalous' diffusion results from pitch-angle diffusion caused by wave turbulence combined with drift-shell splitting, an effect recently studied by O'Brien in the outer radiation belt. We have constructed a comprehensive model of neoclassical diffusion at low L as a function of pitch-angle, energy and L-shell, and find that we quantitatively reproduce the results in Newkirk and Walt and Imhof et al, conclusively demonstrating that neoclassical diffusion is an important effect for energetic electrons in the deep inner belt. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MAR.Q2003M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MAR.Q2003M">Using magnons to probe spintronic materials properties</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> McMichael, Robert 2012-02-01 For many spin-based electronic devices, from the read sensors in modern hard disk drives to future spintronic logic concepts, the device physics originates in spin polarized currents in ferromagnetic metals. In this talk, I will describe a novel ``Spin Wave Doppler'' method that uses the interaction of spin waves with spin-polarized currents to determine the spin drift velocity and the spin current polarization [1]. Owing to differences between the band structures of majority-spin and minority-spin electrons, the electrical current also carries an angular momentum current and magnetic moment current. Passing these coupled currents though a magnetic wire changes the linear excitations of the magnetization, i.e spin waves. Interestingly, the excitations can be described as drifting ``downstream'' with the electron flow. We measure this drift velocity by monitoring the spin-wave-mediated transmission between pairs of periodically patterned antennas on magnetic wires as a function of current density in the wire. The transmission frequency resonance shifts by 2πδf = vk where the drift velocity v is proportional to both the current density and the current polarization P. I will discuss measurements of the spin polarization of the current in Ni80Fe20 [2], and novel alloys (CoFe)1-xGax [3] and (Ni80Fe20)1-xGdx [4]. [4pt] [1] V. Vlaminck and M. Bailleul, Science, 322, 410 (2008) [0pt] [2] M. Zhu, C. L. Dennis, and R. D. McMichael, Phys. Rev. B, 81, 140407 (2010). [0pt] [3] M. Zhu, B. D. Soe, R. D. McMichael, M. J. Carey, S. Maat, and J. R. Childress, Appl. Phys. Lett., 98, 072510 (2011). [0pt] [4] R. L. Thomas, M. Zhu, C. L. Dennis, V. Misra and R. D. McMichael, J. Appl. Phys., 110, 033902 (2011). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.789H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.789H">Summary of types of radiation belt electron precipitation observed by BARREL</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Halford, Alexa 2016-07-01 The Balloon Array for Relativistic Radiation belt Electron Loss (BARREL) was able to infer precipitation of radiation belt electrons on multiple time scales and due to multiple loss mechanisms. One storm will be specifically highlighted which occurred on 26 January 2013 when a solar wind shock hit the Earth. Although MeV electrons were observed to be lost due to an EMIC wave event [Zhang et al in prep], and multiple periods of electron loss during substorms were observed [Rae et al submitted JGR, Mann et al in prep], we will consider an event period where loss associated with multiple time scales, and thus possibly different loss mechanisms was observed from 1000 - 1200 UT on 26 January 2013. At about 1005 UT on 26 January 2013 an injection of radiation belt electrons followed by drift echoes for energies of ˜80 - 400 keV. BARREL observed X-rays with energies less than 180 keV associated with multiple temporal structures during the drift echo event period. The Van Allen Probes were at similar L-values but upwards of 2 hours away in MLT. Upper band chorus and ULF waves were observed during the event period. Throughout the beginning of the event period, microbursts were clearly observed. During this time lower band chorus waves as well as time domain structures were observed at Van Allen Probe A located upwards of 2 hours away in MLT. This large difference in MLT meant that neither potential loss mechanism was able to be clearly associated with the microbursts. As the lower band chorus and time domain structures were observed to recede, the microbursts were also observed to subside. ULF time scale modulation of the X-rays was also observed throughout most of the event period. We will examine if the ULF waves are the cause of the precipitation themselves, or are modulating the loss of particles from a secondary loss mechanism [Brito et al 2015 JGR, Rae et al Submitted JGR]. Although the 100s ms and ULF time scales are clearly observed, there is an ˜20 minute overarching structure observed in the X-rays at BARREL. This longer time scale appears to match the drift period of the ˜300 keV electrons observed by the Van Allen probes. However the inferred energy of the precipitating electrons is ˜150 keV. It is unclear what may be causing the ˜20 minute structure in the X-rays. At the time of writing this abstract, it is unclear if the drifting of the 300 keV electrons is related to the precipitation of the lower energy electrons (< 180 keV) or if it is just coincidence that they have the same temporal structure. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/616411-electroluminescence-xe-ne-gas-mixtures-monte-carol-simulation-study','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/616411-electroluminescence-xe-ne-gas-mixtures-monte-carol-simulation-study">The electroluminescence of Xe-Ne gas mixtures: A Monte Carol simulation study</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Santos, F.P.; Dias, T.H.V.T.; Rachinhas, P.J.B.M. 1998-04-01 The authors have performed a Monte Carlo simulation of the drift of electrons through a mixture of gaseous xenon with the lighter noble gas neon at a total pressure of 1 atm. The electroluminescence characteristics and other transport parameters are investigated as a function of the reduced electric field and composition of the mixture. For Xe-Ne mixtures with 5, 10, 20, 40, 70, 90, and 100% of Xe, they present results for electroluminescence yield and excitation efficiency, average electron energy, electron drift velocity, reduced mobility, reduced diffusion coefficients, and characteristic energies over a range of reduced electric fields which excludemore » electron multiplication. For the 5% Xe mixture, they also assess the influence of electron multiplication on the electroluminescence yield. The present study of Xe-Ne mixtures was motivated by an interest in using them as a filling for gas proportional scintillation counters in low-energy X-ray applications. In this energy range, the X rays will penetrate further into the detector due to the presence of Ne, and this will lead to an improvement in the collection of primary electrons originating near the detector window and may represent an advantage over the use of pure Xe.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPTP8049L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPTP8049L">Kinetic stability analysis on electromagnetic filamentary structure</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lee, Wonjae; Krasheninnikov, Sergei 2014-10-01 A coherent radial transport of filamentary structures in SOL region is important for its characteristics that can increase unwanted high fluxes to plasma facing components. In the course of propagation in radial direction, the coherency of the filaments is significantly limited by electrostatic resistive drift instability (Angus et al., 2012). Considering higher plasma pressure, which would have more large impact in heat fluxes, electromagnetic effects will reduce the growth rate of the drift wave instability and increase the instabilities from electron inertial effects. According to a linear stability analysis on equations with fluid approximation, the maximum growth rate of the instability from the electron inertia is higher than that of drift-Alfvén wave instability in high beta filaments such as ELMs. However, the analysis on the high beta filaments requires kinetic approach, since the decreased collisionality will make the fluid approximation broken. Therefore, the kinetic analysis will be presented for the electromagnetic effects on the dynamics of filamentary structures. This work was supported by the USDOE Grants DE-FG02-04ER54739 and DE-SC0010413 at UCSD and also by the Kwanjeong Educational Foundation. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active">18</li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active">19</li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/919410','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/919410">Detection of Instrumental Drifts in the PEP II LER BPM System</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Wittmer, W.; Fisher, A.S.; Martin, D.J. 2007-11-07 During the last PEP-II run a major goal was to bring the Low-Energy Ring optics as close as possible to the design. A large number of BPMs exhibited sudden artificial jumps that interfered with this effort. The source of the majority of these jumps had been traced to the filter-isolator boxes (FIBs) near the BPM buttons. A systematic approach to find and repair the failing units had been developed and implemented. Despite this effort, the instrumental orbit jumps never completely disappeared. To trace the source of this behavior a test setup, using a spare Bergoz MX-BPM processor (kindly provided bymore » SPEAR III at SSRL), was connected in parallel to various PEP-II BPM processors. In the course of these measurements a slow instrumental orbit drift was found which was clearly not induced by a moving positron beam. Based on the size of the system and the limited time before PEP-II closes in Oct.2008, an accelerator improvement project was initiated to install BERGOZ BPM-MX processors close to all sextupoles.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA435788','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA435788">Imaging and Forecasting of Ionospheric Structures and Their System Impacts</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2005-01-27 Radiation Belt Remediation (RBR) studies were done and many of them remain active. The results of two HAARP heating experiments with the digisonde at...LORERS, Plasmasphere, HAARP , Cal/Val, Drift Software, ARTIST 4.5 16. SECURITY CLASSIFICATION OF: 17. UMITATION OF 1. NUMBER 19a. NAME OF RESPONSIBLE...STATION OBSERVATIONS 1 1.3 VLF INDUCED ELECTRON PITCH ANGLE SCATTERING (IEPAS) 2 1.4 HAARP CAMPAIGN 2 1.5 DRIFT SOFTWARE DEVELOPMENT 2 1.6 DISS SUPPORT </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6527008-resonance-localization-poloidal-electric-field-due-cyclo-tron-wave-heating-tokamak-plasmas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6527008-resonance-localization-poloidal-electric-field-due-cyclo-tron-wave-heating-tokamak-plasmas">Resonance localization and poloidal electric field due to cyclo- tron wave heating in tokamak plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hsu, J.Y.; Chan, V.S.; Harvey, R.W. 1984-08-06 The perpendicular heating in cyclotron waves tends to pile up the resonant particles toward the low magnetic field side with their banana tips localized to the resonant surface. A poloidal electric field with an E x B drift comparable to the ion vertical drift in a toroidal magnetic field may result. With the assumption of anomalous electron and neoclassical ion transport, density variations due to wave heating are discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/197162','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/197162">DOE Project 353: TAMS Prototype and production coupling alignment units</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Field, K.V. 1996-02-01 TAMS is an electronic measurement system used to determine the alignment of turbine-generator shafts at the coupling interface. The displacement transducer is a strain gage based sensor mounted in a portable probe. The measurement system was experiencing zero input drift and temperature induced drift. This project endeavored to determine the source of these problems and to revise a unit to be returned to a customer, Baltimore Gas and Electric (BGE), within a period of five weeks. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25856883','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25856883">[Further study on possibility of diffusion of Oncomelania hupensis with water in river channels of the east route of South-to-North Water Diversion Project].</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Huang, Yi-Xin; Hang, De-Rong; Tang, Hong-Ping; Sun, Dao-Kuan; Zhou, Can-Hua; Gao, Jin-Bin; Zheng, Bo; Hu, Gui-Quan; Li, Qian; Huang, Yong-Jun; She, Guang-Song; Ren, Zhi-Yuan 2014-12-01 To study the drifting law of floats and potential risks of Oncomelania hupensis diffusion in the water diversion rivers of the east route of South-to-North Water Diversion Project. The O. hupensis snails in the river channels were monitored by the salvage method and snail luring method with rice straw curtains, and the diffusion possibility of snails along with water was assessed through the drift test of floats with GPS. In the flood seasons from 2006 to 2013, totally 8 338.0 kg of floats were salvaged, and 2 100 rice straw curtains were put into water in the Li Canal and Jinbao shipping channel, but no Oncomelania snails were found. The drift test of floats with GPS before water diversion showed that the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.56 - 0.60 m/s, and the average drift distances each time were 999.70 - 1 995.50 m in the Gaoshui River section, while there were no obvious drift in Jinbao shipping channel section. During the water diversion period, the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.35 - 0.41m/s, and the average drift distances each time were 1 248.06 -1 289.44 m in the Gaoshui River, while in Jinbao shipping channel section, the flow velocity on water surface was 0.28 m/s, the average drift velocity of the floats was 0.25 - 0.27 m/s, and the average drift distances each time were 477.76 - 496.38 m. The drift test showed that the floats gradually closed to the river bank as affected by water flow, wind direction and ship waves, when blocked by the reeds, water plants or other obstacles, and they would stopped and could not continue to drift without outside help. There are no Oncomelania snails found in the river channels of the east route of South-to-North Water Diversion Project. The drifting distance of the floating debris along with the water is restricted by the flow rate and shore environment. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/20797940-electromagnetic-model-lightning-dart-leader-earth-atmosphere','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/20797940-electromagnetic-model-lightning-dart-leader-earth-atmosphere">Electromagnetic Model Of A Lightning Dart Leader In The Earth Atmosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Gordeev, A. V.; Losseva, T. V. 2006-01-15 The fundamentally new approach to the lightning step and dart leaders structure model is suggested, which shows a possibility of the drift propagation for the electrons in a plasma channel. Appearance of the strong Hall electric field in the current channel by the account of the magnetic field can result in the generation of the relativistic drifting electrons to be held in the channel due to the magnetic self-insulation effect. The range of the measured x-ray emission from the lightning channel 30-250 keV, which corresponds to the measured current value 4-11 kA, is in a reasonably good agreement with themore » estimates made in the framework of presented model.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JAP....92.3410T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JAP....92.3410T">Electron emission from deep level defects EL2 and EL6 in semi-insulating GaAs observed by positron drift velocity transient measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tsia, J. M.; Ling, C. C.; Beling, C. D.; Fung, S. 2002-09-01 A plus-or-minus100 V square wave applied to a Au/semi-insulating SI-GaAs interface was used to bring about electron emission from and capture into deep level defects in the region adjacent to the interface. The electric field transient resulting from deep level emission was studied by monitoring the positron drift velocity in the region. A deep level transient spectrum was obtained by computing the trap emission rate as a function of temperature and two peaks corresponding to EL2 (Ea=0.81plus-or-minus0.15 eV) and EL6 (Ea=0.30plus-or-minus0.12 eV) have been identified. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...829...87A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...829...87A">Extended MHD Turbulence and Its Applications to the Solar Wind</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Abdelhamid, Hamdi M.; Lingam, Manasvi; Mahajan, Swadesh M. 2016-10-01 Extended MHD is a one-fluid model that incorporates two-fluid effects such as electron inertia and the Hall drift. This model is used to construct fully nonlinear Alfvénic wave solutions, and thereby derive the kinetic and magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the constant cascading rates of the energy and generalized helicities of this model. The magnetic and kinetic spectra are derived in the ideal (k\\lt 1/{λ }I), Hall (1/{λ }I\\lt k\\lt 1/{λ }e), and electron inertia (k\\gt 1/{λ }e) regimes; k is the wavenumber and {λ }s=c/{ω }{ps} is the skin depth of species “s.” In the Hall regime, it is shown that the emergent results are fully consistent with previous numerical and analytical studies, especially in the context of the solar wind. The focus is primarily on the electron inertia regime, where magnetic energy spectra with power-law indexes of -11/3 and -13/3 are always recovered. The latter, in particular, is quite close to recent observational evidence from the solar wind with a potential slope of approximately -4 in this regime. It is thus plausible that these spectra may constitute a part of the (extended) inertial range, as opposed to the standard “dissipation” range paradigm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/922705','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/922705">Germanium: From Its Discovery to SiGe Devices</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Haller, E.E. 2006-06-14 Germanium, element No.32, was discovered in 1886 by Clemens Winkler. Its first broad application was in the form of point contact Schottky diodes for radar reception during WWII. The addition of a closely spaced second contact led to the first all-solid-state electronic amplifier device, the transistor. The relatively low bandgap, the lack of a stable oxide and large surface state densities relegated germanium to the number 2 position behind silicon. The discovery of the lithium drift process, which made possible the formation of p-i-n diodes with fully depletable i-regions several centimeters thick, led germanium to new prominence as the premiermore » gamma-ray detector. The development of ultra-pure germanium yielded highly stable detectors which have remained unsurpassed in their performance. New acceptors and donors were discovered and the electrically active role of hydrogen was clearly established several years before similar findings in silicon. Lightly doped germanium has found applications as far infrared detectors and heavily Neutron Transmutation Doped (NTD) germanium is used in thermistor devices operating at a few milliKelvin. Recently germanium has been rediscovered by the silicon device community because of its superior electron and hole mobility and its ability to induce strains when alloyed with silicon. Germanium is again a mainstream electronic material.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...119b3304B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...119b3304B">Magnetically insulated coaxial vacuum diode with partial space-charge-limited explosive emission from edge-type cathode</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Belomyttsev, S. Ya.; Rostov, V. V.; Romanchenko, I. V.; Shunailov, S. A.; Kolomiets, M. D.; Mesyats, G. A.; Sharypov, K. A.; Shpak, V. G.; Ulmaskulov, M. R.; Yalandin, M. I. 2016-01-01 The vacuum current associated with any type of electron emission for arbitrary configuration of the diode depends on the combination of the applied electric field and vacuum space charge (VSC) field created by the current. Such fundamental statement should give very close links between the diode current and the normalized cathode field θ which has been introduced by Forbes in 2008 for planar diodes as a reduction in the cathode surface field: θ = field-with/field-without VSC. This article reports the universal approximation of the type of cos(πθ/2) that is the ratio of the actual current and the fully space-charge-limited current. Also, the theoretical treatment and the experimental method of determination of the dynamic emissive characteristics of the macroscopic explosive emission from edge-type cathodes in the coaxial diode are developed. The experimental results obtained with a picosecond time reference between the cathode voltage and the onset of the high-current electron beam exhibit a good coincidence with the theoretical predictions. The presented methods enable the analysis of a real-time-resolved dynamics associated with the dense, magnetized electron beam formation, acceleration and drift motion, including kinematic effects and the phase-stable excitation of high-power microwave oscillators. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22494884-magnetically-insulated-coaxial-vacuum-diode-partial-space-charge-limited-explosive-emission-from-edge-type-cathode','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22494884-magnetically-insulated-coaxial-vacuum-diode-partial-space-charge-limited-explosive-emission-from-edge-type-cathode">Magnetically insulated coaxial vacuum diode with partial space-charge-limited explosive emission from edge-type cathode</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Belomyttsev, S. Ya.; Rostov, V. V.; Romanchenko, I. V. 2016-01-14 The vacuum current associated with any type of electron emission for arbitrary configuration of the diode depends on the combination of the applied electric field and vacuum space charge (VSC) field created by the current. Such fundamental statement should give very close links between the diode current and the normalized cathode field θ which has been introduced by Forbes in 2008 for planar diodes as a reduction in the cathode surface field: θ = field-with/field-without VSC. This article reports the universal approximation of the type of cos(πθ/2) that is the ratio of the actual current and the fully space-charge-limited current. Also, themore » theoretical treatment and the experimental method of determination of the dynamic emissive characteristics of the macroscopic explosive emission from edge-type cathodes in the coaxial diode are developed. The experimental results obtained with a picosecond time reference between the cathode voltage and the onset of the high-current electron beam exhibit a good coincidence with the theoretical predictions. The presented methods enable the analysis of a real-time-resolved dynamics associated with the dense, magnetized electron beam formation, acceleration and drift motion, including kinematic effects and the phase-stable excitation of high-power microwave oscillators.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.4031G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.4031G">Triggered emissions close to the proton gyrofrequency seen by Cluster</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Grison, Benjamin; Pickett, Jolene; Omura, Yoshiharu; Santolik, Ondrej; Decreau, Pierrette; Masson, Arnaud; Engebretson, Mark; Cornilleau-Wehrlin, Nicole; Robert, Patrick; Dandouras, Iannis Electromagnetic ion cyclotron (EMIC) triggered emissions have been recently observed onboard the Cluster spacecraft close to the plasmapause in the equatorial region of the magnetosphere. These waves appear as "risers": electromagnetic structures that have a positive frequency drift with time, i.e., the EMIC analogue of rising frequency whistler mode triggered emissions and chorus waves. In our first results concerning the emission process based on a single event, these risers have the following properties: they propagate away from the direction of the magnetic equator, they have elliptical left-handed polarization corresponding to the transverse Alfven mode, and frequency drifts of about 30 mHz/s. These risers are not common in the Cluster data set. Nevertheless a few other events were found with similar properties. Another interesting preliminary result is the existence of risers with a polarization opposite that of the EMIC triggered emissions and which correspond to the fast magnetosonic mode. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910062756&hterms=Open+Field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DOpen%2BField','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910062756&hterms=Open+Field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DOpen%2BField">Sondrestrom radar measurements of the reconnection electric field</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> De La Beaujardiere, O.; Lyons, L. R.; Friis-Christensen, E. 1991-01-01 The possibility of using Sondrestrom incoherent radar scatter to estimate the rate of solar-wind energy transfer is examined by using plasma-velocity measurements in the separatrix reference frame. The separatrix is the boundary between open and closed field lines, and its orientation is deduced from all-sky images. The radar observations are used to determine the separatrix location and the ionospheric plasma drift. Measurements of the reconnection electric field in the midnight sector for one night are taken, revealing that the field is less than 15 mV/m during the time of local polar-cap extension. During polar-cap contraction the field range is 30-40 mV/m, and these periods correspond to substorm expansive phases. The limitations associated with measuring ionospheric plasma drift, the boundary orientation, and boundary location are enumerated. The measurements in the experimental case demonstrate the possibility of plasma transfer from closed to open field lines. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JTePh..63..467D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JTePh..63..467D">Extension of the Mott-Gurney Law for a Bilayer Gap</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dubinov, A. E.; Kitayev, I. N. 2018-04-01 Steady drift states of an electron flow in a planar gap filled with a bilayer dielectric have been considered. Exact mathematical formulas have been derived that describe the distributions of the electrostatic potential and space charge limited electron flow current (extended Mott-Gurney law for a bilayer diode). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150008358','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150008358">Plasma in Saturn's Nightside Magnetosphere and the Implications for Global Circulation</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> McAndrews, H.J.; Thomsen, M.F.; Arridge, C.S.; Jackman, C.M.; Wilson, R.J.; Henderson, M.G.; Tokar, R.L.; Khurana, K.K.; Sittler, E. C.; Coates, A.J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150008358'); toggleEditAbsImage('author_20150008358_show'); toggleEditAbsImage('author_20150008358_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150008358_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150008358_hide"> 2009-01-01 We present a bulk ion flow map from the nightside, equatorial region of Saturn's magnetosphere derived from the Cassini CAPS ion mass spectrometer data. The map clearly demonstrates the dominance of corotation flow over radial flow and suggests that the flux tubes sampled are still closed and attached to the planet up to distances of 50RS. The plasma characteristics in the near-midnight region are described and indicate a transition between the region of the magnetosphere containing plasma on closed drift paths and that containing flux tubes which may not complete a full rotation around the planet. Data from the electron spectrometer reveal two plasma states of high and low density. These are attributed either to the sampling of mass-loaded and depleted flux tubes, respectively, or to the latitudinal structure of the plasma sheet. Depleted, returning flux tubes are not, in general, directly observed in the ions, although the electron observations suggest that such a process must take place in order to produce the low-density population. Flux-tube content is conserved below a limit defined by the mass-loading and magnetic field strength and indicates that the flux tubes sampled may survive their passage through the tail. The conditions for mass-release are evaluated using measured densities, angular velocities and magnetic field strength. The results suggest that for the relatively dense ion populations detectable by the ion mass spectrometer (IMS), the condition for flux-tube breakage has not yet been exceeded. However, the low-density regimes observed in the electron data suggest that loaded flux tubes at greater distances do exceed the threshold for mass-loss and subsequently return to the inner magnetosphere significantly depleted of plasma. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714730F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714730F">DREAM-3D and the importance of model inputs and boundary conditions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Friedel, Reiner; Tu, Weichao; Cunningham, Gregory; Jorgensen, Anders; Chen, Yue 2015-04-01 Recent work on radiation belt 3D diffusion codes such as the Los Alamos "DREAM-3D" code have demonstrated the ability of such codes to reproduce realistic magnetospheric storm events in the relativistic electron dynamics - as long as sufficient "event-oriented" boundary conditions and code inputs such as wave powers, low energy boundary conditions, background plasma densities, and last closed drift shell (outer boundary) are available. In this talk we will argue that the main limiting factor in our modeling ability is no longer our inability to represent key physical processes that govern the dynamics of the radiation belts (radial, pitch angle and energy diffusion) but rather our limitations in specifying accurate boundary conditions and code inputs. We use here DREAM-3D runs to show the sensitivity of the modeled outcomes to these boundary conditions and inputs, and also discuss alternate "proxy" approaches to obtain the required inputs from other (ground-based) sources. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12210287P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12210287P">Quantifying the Precipitation Loss of Radiation Belt Electrons During a Rapid Dropout Event</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pham, K. H.; Tu, W.; Xiang, Z. 2017-10-01 Relativistic electron flux in the radiation belt can drop by orders of magnitude within the timespan of hours. In this study, we used the drift-diffusion model that includes azimuthal drift and pitch angle diffusion of electrons to simulate low-altitude electron distribution observed by POES/MetOp satellites for rapid radiation belt electron dropout event occurring on 1 May 2013. The event shows fast dropout of MeV energy electrons at L > 4 over a few hours, observed by the Van Allen Probes mission. By simulating the electron distributions observed by multiple POES satellites, we resolve the precipitation loss with both high spatial and temporal resolutions and a range of energies. We estimate the pitch angle diffusion coefficients as a function of energy, pitch angle, and L-shell and calculate corresponding electron lifetimes during the event. The simulation results show fast electron precipitation loss at L > 4 during the electron dropout, with estimated electron lifetimes on the order of half an hour for MeV energies. The electron loss rate shows strong energy dependence with faster loss at higher energies, which suggest that this dropout event is dominated by quick and localized scattering process that prefers higher energy electrons. The improved temporal and spatial resolutions of electron precipitation rates provided by multiple low-altitude observations can resolve fast-varying electron loss during rapid electron dropouts (over a few hours), which occur too fast for a single low-altitude satellite. The capability of estimating the fast-varying electron lifetimes during rapid dropout events is an important step in improving radiation belt model accuracy. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22078287-recirculating-planar-magnetrons-simulations-experiment','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22078287-recirculating-planar-magnetrons-simulations-experiment">Recirculating planar magnetrons: simulations and experiment</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Franzi, Matthew; Gilgenbach, Ronald; French, David 2011-07-01 The Recirculating Planar Magnetron (RPM) is a novel crossed-field device whose geometry is expected to reduce thermal load, enhance current yield as well as ease the geometric limitations in scaling to high RF frequencies as compared to the conventional cylindrical magnetrons. The RPM has two different adaptations: A. Axial B field and radial E field; B. Radial B field and axial E field. The preliminary configuration (A) to be used in experiments at the University of Michigan consists of two parallel planar sections which join on either end by cylindrical regions to form a concentric extruded ellipse. Similar to conventionalmore » magnetrons, a voltage across the AK gap in conjunction with an axial magnetic field provides the electrons with an ExB drift. The device is named RPM because the drifting electrons recirculate from one planar region to the other. The drifting electrons interact with the resonantly tuned slow wave structure on the anode causing spoke formation. These electron spokes drive a RF electric field in the cavities from which RF power may be extracted to Waveguides. The RPM may be designed in either a conventional configuration with the anode on the outside, for simplified extraction, or as an inverted magnetron with the anode at the inner conductor, for fast start-up. Currently, experiments at the Pulsed Power and Microwave Laboratory at the University of Michigan are in the setup and design phase. A conventional RPM with planar cavities is to be installed on the Michigan Electron Long Beam Accelerator (MELBA) and is anticipated to operate at -200kV, 0.2T with a beam current of 1-10 kA at 1GHz. The conventional RPM consists of 12 identical planar cavities, 6 on each planar side, with simulated quality factor of 20.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..MARV32009B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..MARV32009B">Electron Drift Speed And Current-Induced Drive Torques On A Domain Wall</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Berger, Luc 2009-03-01 It has become fashionable to describe [1] current-induced torques on a DW in terms of an electron drift speed u = - P*j*muB/e*M where muB is the Bohr magneton and M the saturation magnetization. While appropriate for adiabatic torques, this quantity u is misleading and not the best choice in the case of non-adiabatic torques. For example, it leads [2] to beta not equal to alpha, where beta represents the intensity of the non-adiabatic torque, and alpha is the damping parameter. By writing equations of motion for conduction- electron spins in a moving frame where the electron gas is at rest, we find [3] a direct relation between damping and non- adiabatic torques. The correct electron drift speed turns out to be the speed of the frame, and is v = P*j/(n*q) where n and q are the carrier density and charge. It is related to the ordinary Hall constant R0 by v P*R0*j. After substituting v for u in the expression of the non-adiabatic torque, we find that beta = alpha holds now. Because v is larger than u in Permalloy, it can explain better the large current-induced DW speeds found [4] experimentally. In materials where R0> 0 and the carriers are dominantly hole-like, v and u have opposite signs, leading to different predictions for the sense of DW motion. We discuss examples of such materials. 1. G. Tatara and H. Kohno, Phys. Rev. Lett. 92, 086601 (2004). 2. H. Kohno et al., J. Phys. Soc. Japan, 75, 113706 (2006). 3. L. Berger, Phys. Rev. B 75, 174401 (2007). 4. M. Hayashi et al., Phys. Rev. Lett. 98, 037204 (2007). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002PhPl....9..177R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PhPl....9..177R">Comparing simulation of plasma turbulence with experiment</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ross, David W.; Bravenec, Ronald V.; Dorland, William; Beer, Michael A.; Hammett, G. W.; McKee, George R.; Fonck, Raymond J.; Murakami, Masanori; Burrell, Keith H.; Jackson, Gary L.; Staebler, Gary M. 2002-01-01 The direct quantitative correspondence between theoretical predictions and the measured plasma fluctuations and transport is tested by performing nonlinear gyro-Landau-fluid simulations with the GRYFFIN (or ITG) code [W. Dorland and G. W. Hammett, Phys. Fluids B 5, 812 (1993); M. A. Beer and G. W. Hammett, Phys. Plasmas 3, 4046 (1996)]. In an L-mode reference discharge in the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)], which has relatively large fluctuations and transport, the turbulence is dominated by ion temperature gradient (ITG) modes. Trapped electron modes and impurity drift waves also play a role. Density fluctuations are measured by beam emission spectroscopy [R. J. Fonck, P. A. Duperrex, and S. F. Paul, Rev. Sci. Instrum. 61, 3487 (1990)]. Experimental fluxes and corresponding diffusivities are analyzed by the TRANSP code [R. J. Hawryluk, in Physics of Plasmas Close to Thermonuclear Conditions, edited by B. Coppi, G. G. Leotta, D. Pfirsch, R. Pozzoli, and E. Sindoni (Pergamon, Oxford, 1980), Vol. 1, p. 19]. The shape of the simulated wave number spectrum is close to the measured one. The simulated ion thermal transport, corrected for E×B low shear, exceeds the experimental value by a factor of 1.5 to 2.0. The simulation overestimates the density fluctuation level by an even larger factor. On the other hand, the simulation underestimates the electron thermal transport, which may be accounted for by modes that are not accessible to the simulation or to the BES measurement. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active">19</li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active">20</li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6696628-lion-roars-nonoscillatory-drift-mirror-waves-magnetosheath','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6696628-lion-roars-nonoscillatory-drift-mirror-waves-magnetosheath">Lion roars and nonoscillatory drift mirror waves in the magnetosheath</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Tsurutani, B.T.; Smith, E.J.; Anderson, R.R. 1982-08-01 A complete set of ISEE plasma wave, plasma, and field data are used to identify the plasma instability responsible for the generation of extremely low frequency (ELF) electromagnetic lion roars. Lion roars detected close to the magnetopause are generated by the cyclotron instability of anisotropic (T/sup -//sub perpendicular//T/sup -//sub parallel/approx. =1.2) thermal electrons when the local plasma critical energy, E/sub M/ = B/sup 2//8..pi..N, falls to values (E/sub M/ approx.10--30 eV) close to or below the electron thermal energy, 25 eV, as a result of decreases in B. The lion roars are terminated by increases in the ambient magnetic fieldmore » magnitude and consequential increases in E/sub M/ to values greater than 100 eV. Because there are few resonant particles at these high energies, the growth rate decreases by 3 orders of magnitude and measurable growth ceases. The value of the absolute upper limit of the frequency of unstable waves predicted by theory, ..omega../sub max/ = A/sup -/..cap omega../sup -//(A/sup -/+1), is compared with observations. The predictions and observations are found to be in general, but not exact, agreement. Several possible explanations are explored. The quasi-periodic, approx.20-s magnetic and plasma oscillations which cause the variations in E/sub M/ and hence alternately drive the cyclotron waves unstable and then stable are also investigated.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..APR.C9001N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..APR.C9001N">A Micromegas-based Directional Dark Matter Detector for Use with Negative Ion Gases</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nicoloff, Catherine; Battat, James 2017-01-01 Directional dark matter detectors seek to measure the direction of WIMP-induced nuclear recoils. The angular distribution of these recoils provides a unique signature that is not mimicked by any known background population. Low-pressure gas time projection chambers (TPCs) have a long and successful history in directional dark matter searches. The benefit of the low-pressure gas target is that nuclear recoils from dark matter extend long enough to be reliably reconstructed. For the last decade, the DRIFT collaboration has employed a MWPC-based negative-ion TPC for directional dark matter detection. DRIFT recently published the leading limit from a directional detector on the spin-dependent WIMP-proton interaction (1.1 pb at a WIMP mass of 100 GeV/c2) . Although the effective spatial granularity along the drift direction is 60 um, the MWPC wire spacing of 2 mm limits DRIFT's track reconstruction. DRIFT is now exploring TPC readouts that offer higher spatial resolution. Here, we report on one such effort that uses a Micromegas for gas amplification with orthogonal strips for charge signal readout. The detector can be used with both electron drift and negative ion gases. We will describe the detector design and present preliminary commissioning data taken in a surface laboratory. Research Corporation, NSF, and MA Space Grant. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1342004','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1342004">Attenuation Drift in the Micro-Computed Tomography System at LLNL</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Dooraghi, Alex A.; Brown, William; Seetho, Isaac 2016-01-12 The maximum allowable level of drift in the linear attenuation coefficients (μ) for a Lawrence Livermore National Laboratory (LLNL) micro-computed tomography (MCT) system was determined to be 0.1%. After ~100 scans were acquired during the period of November 2014 to March 2015, the drift in μ for a set of six reference materials reached or exceeded 0.1%. Two strategies have been identified to account for or correct the drift. First, normalizing the 160 kV and 100 kV μ data by the μ of water at the corresponding energy, in contrast to conducting normalization at the 160 kV energy only, significantlymore » compensates for measurement drift. Even after the modified normalization, μ of polytetrafluoroethylene (PTFE) increases linearly with scan number at an average rate of 0.00147% per scan. This is consistent with PTFE radiation damage documented in the literature. The second strategy suggested is the replacement of the PTFE reference with fluorinated ethylene propylene (FEP), which has the same effective atomic number (Ze) and electron density (ρe) as PTFE, but is 10 times more radiation resistant. This is important as effective atomic number and electron density are key parameters in analysis. The presence of a material with properties such as PTFE, when taken together with the remaining references, allows for a broad range of the (Ze, ρe) feature space to be used in analysis. While FEP is documented as 10 times more radiation resistant, testing will be necessary to assess how often, if necessary, FEP will need to be replaced. As radiation damage to references has been observed, it will be necessary to monitor all reference materials for radiation damage to ensure consistent x-ray characteristics of the references.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP51E1175B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP51E1175B">Cenozoic Circulation History of the North Atlantic Ocean From Seismic Stratigraphy of the Newfoundland Ridge Drift Complex</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Boyle, P. R.; Romans, B.; Norris, R. D.; Tucholke, B. E.; Swift, S. A.; Sexton, P. F. 2014-12-01 In the North Atlantic Ocean, contour-following bottom currents have eroded regional unconformities and deposited contourite drifts that exceed two km in thickness and extend for 100s of km. The character of deep-water masses that are conveyed through ocean basins by such currents influence global heat transfer and ocean-atmosphere partitioning of CO2. The Newfoundland Ridge Drift Complex lies directly under the modern Deep Western Boundary Current southeast of Newfoundland, close to the site of overturning in the northwest Atlantic Ocean and at the intersection of the warm Gulf Stream and cool Labrador surface currents. To the south are regions of the western North Atlantic basin that are influenced by southern- as well as northern-sourced bottom waters. Here, we document the evolution of North Atlantic deep-water circulation by seismic-stratigraphic analysis of the long-lived and areally extensive Newfoundland Ridge Drift Complex. IODP Expedition 342 boreholes provide age control on seismic units, allowing sedimentation patterns to be placed in a temporal framework. We find three major phases of sedimentation: pre-contourite drift (~115-50 Ma), active contourite drift (~50-2.6 Ma), and late-contourite drift (~2.6-0 Ma). Bottom-current-controlled deposition of terrigenous-rich sediment began at ~50 Ma, which correlates to the onset of a long-term global cooling trend. A further change in deep circulation near the Eocene-Oligocene transition (~30 Ma) is indicated by more focused drift sedimentation with greatly increased accumulation rates and stratal architecture dominated by mud waves. At ~2.6 Ma to present the axis of drift accumulation shifted markedly towards shallower water depths, corresponding with the onset of Northern Hemisphere ice sheets. We discuss how these reorganizations of deep circulation correlate with results of other North Atlantic seismic stratigraphic studies to the north and south. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160010367&hterms=1089&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2526%25231089','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160010367&hterms=1089&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2526%25231089">Suppression of Collisionless Magnetic Reconnection in Asymmetric Current Sheets</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Liu, Yi-Hsin; Hesse, Michael 2016-01-01 Using fully kinetic simulations, we study the suppression of asymmetric reconnection in the limit where the diamagnetic drift speed >> Alfven speed and the magnetic shear angle is moderate. We demonstrate that the slippage between electrons and the magnetic flux mitigates the suppression and can even result in fast reconnection that lacks one of the outflow jets. Through comparing a case where the diamagnetic drift is supported by the temperature gradient with a companion case that has a density gradient instead, we identify a robust suppression mechanism. The drift of the x-line is slowed down locally by the asymmetric nature of the x-line, and then the x-line is run over and swallowed by the faster-moving following flux. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850014205','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850014205">A simple model of electron beam initiated dielectric breakdown</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Beers, B. L.; Daniell, R. E.; Delmer, T. N. 1985-01-01 A steady state model that describes the internal charge distribution of a planar dielectric sample exposed to a uniform electron beam was developed. The model includes the effects of charge deposition and ionization of the beam, separate trap-modulated mobilities for electrons and holes, electron-hole recombination, and pair production by drifting thermal electrons. If the incident beam current is greater than a certain critical value (which depends on sample thickness as well as other sample properties), the steady state solution is non-physical. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA561944','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA561944">A Smart Microwave Vacuum Electron Device (MVED) Using Field Emitters</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2012-01-31 operation of the device. By using a larger retardation value, the slow wave phase velocity is decreased allowing a lower E/B drift velocity. By reducing...the drift velocity the device is able to run at a lower cathode potential reducing the risk of high voltage arcing. This new slow wave circuit will...sole electrode above the cathode by using a thin dielectric layer ( mylar ) on top of the cathode and placing the sole electrode on the dielectric </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25424866','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25424866">Illusory body-ownership entails automatic compensative movement: for the unified representation between body and action.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Asai, Tomohisa 2015-03-01 The sense of body-ownership involves the integration of vision and somatosensation. In the rubber hand illusion (RHI), watching a rubber hand being stroked for a short time synchronously as one's own unseen hand is also stroked causes the observers to attribute the rubber hand to their own body. The RHI may elicit proprioceptive drift: The observers' sense of their own hand's location drifts toward the external proxy hand. The current experiments examined the possibility of observing, not the proprioceptive drift, but the actual drift "movement" during RHI induction. The participants' hand, located on horizontally movable board, tended to move toward the rubber hand only while they observed synchronous visuo-tactile stimulation. Furthermore, even when the participants' hand was located on a fixed, unmovable board (that is, the conventional RHI paradigm), participants automatically administered the force toward the rubber hand. These findings suggest that since awareness of our own body and action are fundamental to self-consciousness, these components of "minimal self" are closely related and integrated into "one agent" with a unified awareness of the body and action. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JGR...101.2321B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JGR...101.2321B">The character of drift spreading of artificial plasma clouds in the middle-latitude ionosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Blaunstein, N. 1996-02-01 Nonlinear equations describing the evolution of plasma clouds with real initial sizes, along and across the geomagnetic field B, which drift in the ionosphere in the presence of an ambient electric field and a neutral wind have been solved and analysed. An ionospheric model close to the real conditions of the middle-latitude ionosphere is introduced, taking into account the altitude dependence of the transport coefficients and background ionospheric plasma. The striation of the initial plasma cloud into a cluster of plasmoids, stretched along the field B, is obtained. The process of dispersive splitting of the initial plasma cloud can be understood in terms of gradient drift instability (GDI) as a most probable striation mechanism. The dependence of the characteristic time of dispersive splitting on the value of the ambient electric field, the initial plasma disturbance in the cloud and its initial sizes was investigated. The stretching criterion, necessary for the plasma cloud's striation is obtained. The possibility of the drift stabilization effect arising from azimuthal drift velocity shear, obtained by Drake et al. [1988], is examined for various parameters of the barium cloud and the background ionospheric conditions. A comparison with experimental data on the evolution of barium clouds in rocket experiments at the height of the lower ionosphere is made. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SuMi...75..796Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SuMi...75..796Q">Design of a 1200-V ultra-thin partial SOI LDMOS with n-type buried layer</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Qiao, Ming; Wang, Yuru; Li, Yanfei; Zhang, Bo; Li, Zhaoji 2014-11-01 A novel 1200-V ultra-thin partial silicon-on-insulator (PSOI) lateral double-diffusion metal oxide semiconductor (LDMOS) with n-type buried (n-buried) layer (NBL PSOI LDMOS) is proposed in this paper. The new PSOI LDMOS features an n-buried layer underneath the n-type drift (n-drift) region close to the source side, providing a large conduction region for majority carriers and a silicon window to improve self-heating effect (SHE). A combination of uniform and linear variable doping (ULVD) profile is utilized in the n-drift region, which alleviates the inherent tradeoff between specific on-resistance (Ron,sp) and breakdown voltage (BV). With the n-drift region length of 80 μm, the NBL PSOI LDMOS obtains a high BV of 1243 V which is improved by around 105 V in comparison to the conventional SOI LDMOS with linear variable doping (LVD) profile for the n-drift region (LVD SOI LDMOS). Besides, the 1200-V NBL PSOI LDMOS has a lower maximum temperature (Tmax) of 333 K at a power (P) of 1 mW/μm which is reduced by around 61 K. Meanwhile, Ron,sp and Tmax of the NBL PSOI LDMOS are lower than those of the conventional LVD SOI LDMOS for a wide range of BV. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26651633','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26651633">Recurrent noise-induced phase singularities in drifting patterns.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Clerc, M G; Coulibaly, S; del Campo, F; Garcia-Nustes, M A; Louvergneaux, E; Wilson, M 2015-11-01 We show that the key ingredients for creating recurrent traveling spatial phase defects in drifting patterns are a noise-sustained structure regime together with the vicinity of a phase transition, that is, a spatial region where the control parameter lies close to the threshold for pattern formation. They both generate specific favorable initial conditions for local spatial gradients, phase, and/or amplitude. Predictions from the stochastic convective Ginzburg-Landau equation with real coefficients agree quite well with experiments carried out on a Kerr medium submitted to shifted optical feedback that evidence noise-induced traveling phase slips and vortex phase-singularities. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT.......242K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT.......242K">Microdefects and self-interstitial diffusion in crystalline silicon</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Knowlton, William Barthelemy In this thesis, a study is presented of D-defects and self-interstitial diffusion in silicon using Li ion (Lisp+) drifting in an electric field and transmission electron microscopy (TEM). Obstruction of Lisp+ drifting has been found in wafers from certain but not all FZ p-type Si. Incomplete Lisp+ drifting always occurs in the central region of the wafers. This work established that interstitial oxygen is not responsible for hindering Lisp+ drifting. The Osb i concentration was measured ({˜}2× 10sp{15}\\ cmsp{-3}) by local vibrational mode Fourier transform infrared spectroscopy and did not vary radially across the wafer. TEM was performed on a samples from the partially Lisp+ drifted area and compared to regions without D-defects. Precipitates were found only in the region containing D-defects that had partially Lisp+ drifted. This result indicates D-defects are responsible for the precipitation that halts the Lisp+ drift process. The precipitates were characterized using selected area diffraction (SAD) and image contrast analysis. The results suggested that the precipitates may cause stacking faults and their identity may be lithium silicides such as Lisb{21}Sisb5\\ and\\ Lisb{13}Sisb4. TEM revealed a decreasing distribution of Li precipitates as a function of Lisp+ drift depth along the growth direction. A preliminary model is presented that simulates Lisp+ drifting. The objective of the model is to incorporate the Li precipitate density distribution and Lisp+ drift depth to extract the size and capture cross-section of the D-defects. Nitrogen (N) doping has been shown to eliminate D-defects as measured by conventional techniques. However, Lisp+ drifting has shown that D-defects are indeed still present. Lisp+ drifting is able to detect D-defects at concentrations lower than conventional techniques. Lisp+ drifting and D-defects provide a useful means to study Si self-interstitial diffusion. The process modeling program SUPREM-IV was used to simulate the results of Si self-interstitial diffusion obtained from Lisp+ drifting experiments. Anomalous results from the Si self-interstitial diffusion experiments forced a re-examination of the possibility of thermal dissociation of D-defects. Thermal annealing experiments that were performed support this possibility. A review of the current literature illustrates the need for more research on the effects of thermal processing on FZ Si to understand the dissolution kinetics of D-defects. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28038834','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28038834">Robust image alignment for cryogenic transmission electron microscopy.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> McLeod, Robert A; Kowal, Julia; Ringler, Philippe; Stahlberg, Henning 2017-03-01 Cryo-electron microscopy recently experienced great improvements in structure resolution due to direct electron detectors with improved contrast and fast read-out leading to single electron counting. High frames rates enabled dose fractionation, where a long exposure is broken into a movie, permitting specimen drift to be registered and corrected. The typical approach for image registration, with high shot noise and low contrast, is multi-reference (MR) cross-correlation. Here we present the software package Zorro, which provides robust drift correction for dose fractionation by use of an intensity-normalized cross-correlation and logistic noise model to weight each cross-correlation in the MR model and filter each cross-correlation optimally. Frames are reliably registered by Zorro with low dose and defocus. Methods to evaluate performance are presented, by use of independently-evaluated even- and odd-frame stacks by trajectory comparison and Fourier ring correlation. Alignment of tiled sub-frames is also introduced, and demonstrated on an example dataset. Zorro source code is available at github.com/CINA/zorro. Copyright © 2016 Elsevier Inc. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22046907-suppression-multipactor-discharge-dielectric-surface-external-magnetic-field','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22046907-suppression-multipactor-discharge-dielectric-surface-external-magnetic-field">Suppression of multipactor discharge on a dielectric surface by an external magnetic field</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Cai Libing; Zhu Xiangqin; Wang Yue 2011-07-15 The multipactor discharge on a dielectric surface in an external magnetic field is simulated by using the particle-in-cell method, and the electron number, energy, the velocity of the yield of secondary electrons, and the power deposited on dielectric surface in the process of multipactor discharge are investigated. The effects of the strength of the external magnetic field on multipactor are studied. The results show that when the external magnetic field reaches a certain value, the multipactor is weaker than that in the case of no external magnetic field and becomes much lighter versus the strength of the external magnetic fieldmore » in the half microwave period in which the ExB drift pulls the electrons back to dielectric surface. And in the other half microwave period in which the ExB drift pushes the electrons away from the dielectric surface, the multipactor is cut off. So the power capability can be increased to the fourfold by the suppression of multipactor by applying an external magnetic field.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22314421-accurate-measurement-relative-tilt-azimuth-angles-electron-tomography-comparison-fiducial-marker-method-electron-diffraction','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22314421-accurate-measurement-relative-tilt-azimuth-angles-electron-tomography-comparison-fiducial-marker-method-electron-diffraction"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hayashida, Misa; Malac, Marek; Egerton, Ray F. Electron tomography is a method whereby a three-dimensional reconstruction of a nanoscale object is obtained from a series of projected images measured in a transmission electron microscope. We developed an electron-diffraction method to measure the tilt and azimuth angles, with Kikuchi lines used to align a series of diffraction patterns obtained with each image of the tilt series. Since it is based on electron diffraction, the method is not affected by sample drift and is not sensitive to sample thickness, whereas tilt angle measurement and alignment using fiducial-marker methods are affected by both sample drift and thickness. The accuracy ofmore » the diffraction method benefits reconstructions with a large number of voxels, where both high spatial resolution and a large field of view are desired. The diffraction method allows both the tilt and azimuth angle to be measured, while fiducial marker methods typically treat the tilt and azimuth angle as an unknown parameter. The diffraction method can be also used to estimate the accuracy of the fiducial marker method, and the sample-stage accuracy. A nano-dot fiducial marker measurement differs from a diffraction measurement by no more than ±1°.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030095965','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030095965">Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bloser, P. F.; Hunter, S. D.; Ryan, J. M.; McConnell, M. L.; Miller, R. S.; Jackson, T. N.; Bai, B.; Jung, S. 2003-01-01 We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21824845','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21824845">Incremental learning of concept drift in nonstationary environments.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Elwell, Ryan; Polikar, Robi 2011-10-01 We introduce an ensemble of classifiers-based approach for incremental learning of concept drift, characterized by nonstationary environments (NSEs), where the underlying data distributions change over time. The proposed algorithm, named Learn(++). NSE, learns from consecutive batches of data without making any assumptions on the nature or rate of drift; it can learn from such environments that experience constant or variable rate of drift, addition or deletion of concept classes, as well as cyclical drift. The algorithm learns incrementally, as other members of the Learn(++) family of algorithms, that is, without requiring access to previously seen data. Learn(++). NSE trains one new classifier for each batch of data it receives, and combines these classifiers using a dynamically weighted majority voting. The novelty of the approach is in determining the voting weights, based on each classifier's time-adjusted accuracy on current and past environments. This approach allows the algorithm to recognize, and act accordingly, to the changes in underlying data distributions, as well as to a possible reoccurrence of an earlier distribution. We evaluate the algorithm on several synthetic datasets designed to simulate a variety of nonstationary environments, as well as a real-world weather prediction dataset. Comparisons with several other approaches are also included. Results indicate that Learn(++). NSE can track the changing environments very closely, regardless of the type of concept drift. To allow future use, comparison and benchmarking by interested researchers, we also release our data used in this paper. © 2011 IEEE </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/4330388-final-report-development-geographic-position-locator-gpl-volume-data-reduction-a3fix-subroutine','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4330388-final-report-development-geographic-position-locator-gpl-volume-data-reduction-a3fix-subroutine">Final report on the development of the geographic position locator (GPL). Volume 12. Data reduction A3FIX: subroutine</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Niven, W.A. The long-term position accuracy of an inertial navigation system depends primarily on the ability of the gyroscopes to maintain a near-perfect reference orientation. Small imperfections in the gyroscopes cause them to drift slowly away from their initial orientation, thereby producing errors in the system's calculations of position. The A3FIX is a computer program subroutine developed to estimate inertial navigation system gyro drift rates with the navigator stopped or moving slowly. It processes data of the navigation system's position error to arrive at estimates of the north- south and vertical gyro drift rates. It also computes changes in the east--west gyromore » drift rate if the navigator is stopped and if data on the system's azimuth error changes are also available. The report describes the subroutine, its capabilities, and gives examples of gyro drift rate estimates that were computed during the testing of a high quality inertial system under the PASSPORT program at the Lawrence Livermore Laboratory. The appendices provide mathematical derivations of the estimation equations that are used in the subroutine, a discussion of the estimation errors, and a program listing and flow diagram. The appendices also contain a derivation of closed form solutions to the navigation equations to clarify the effects that motion and time-varying drift rates induce in the phase-plane relationships between the Schulerfiltered errors in latitude and azimuth snd between the Schulerfiltered errors in latitude and longitude. (auth)« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22493929-comparative-study-transport-properties-monolayer-graphene-algan-gan-heterostructure','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22493929-comparative-study-transport-properties-monolayer-graphene-algan-gan-heterostructure">A comparative study of transport properties of monolayer graphene and AlGaN-GaN heterostructure</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ozdemir, M. D.; Atasever, O.; Ozdemir, B. 2015-07-15 The electronic transport properties of monolayer graphene are presented with an Ensemble Monte Carlo method where a rejection technique is used to account for the occupancy of the final states after scattering. Acoustic and optic phonon scatterings are considered for intrinsic graphene and in addition, ionized impurity and surface roughness scatterings are considered for the case of dirty graphene. The effect of screening is considered in the ionized impurity scattering of electrons. The time dependence of drift velocity of carriers is obtained where overshoot and undershoot effects are observed for certain values of applied field and material parameters for intrinsicmore » graphene. The field dependence of drift velocity of carriers showed negative differential resistance and disappeared as acoustic scattering becomes dominant for intrinsic graphene. The variation of electron mobility with temperature is calculated for intrinsic (suspended) and dirty monolayer graphene sheets separately and they are compared. These are also compared with the mobility of two dimensional electrons at an AlGaN/GaN heterostructure. It is observed that interface roughness may become very effective in limiting the mobility of electrons in graphene.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ApPhL..91y2104K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ApPhL..91y2104K">Hot phonon effect on electron velocity saturation in GaN: A second look</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Khurgin, Jacob; Ding, Yujie J.; Jena, Debdeep 2007-12-01 A theoretical model is developed for electron velocity saturation in high power GaN transistors. It is shown that electron velocity at high electric fields is reduced due to heating of electron gas since the high density of nonequilibrium LO phonons cannot efficiently transfer heat to the lattice. However, the resulting degradation of electron velocity is found to be weaker than previously reported. The results are compared with experimental data, and the ways to improve the efficiency of cooling the electron gas to increase the drift velocity are discussed. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active">20</li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active">21</li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830059278&hterms=value+creation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dvalue%2Bcreation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830059278&hterms=value+creation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dvalue%2Bcreation">Creation of high-energy electron tails by means of the modified two-stream instability</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Tanaka, M.; Papadopoulos, K. 1983-01-01 Particle simulations of the modified two-stream instability demonstrate strong electron acceleration rather than bulk heating when the relative drift speed is below a critical speed Vc. A very interesting nonlinear mode transition and autoresonance acceleration process is observed which accelerates the electrons much above the phase speed of the linearly unstable modes. Simple criteria are presented that predict the value of Vc and the number density of the accelerated electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667173-constraining-solar-coronal-magnetic-field-strength-using-split-band-type-ii-radio-burst-observations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667173-constraining-solar-coronal-magnetic-field-strength-using-split-band-type-ii-radio-burst-observations">CONSTRAINING THE SOLAR CORONAL MAGNETIC FIELD STRENGTH USING SPLIT-BAND TYPE II RADIO BURST OBSERVATIONS</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kishore, P.; Ramesh, R.; Hariharan, K. 2016-11-20 We report on low-frequency radio (85–35 MHz) spectral observations of four different type II radio bursts, which exhibited fundamental-harmonic emission and split-band structure. Each of the bursts was found to be closely associated with a whitelight coronal mass ejection (CME) close to the Sun. We estimated the coronal magnetic field strength from the split-band characteristics of the bursts, by assuming a model for the coronal electron density distribution. The choice of the model was constrained, based on the following criteria: (1) when the radio burst is observed simultaneously in the upper and lower bands of the fundamental component, the locationmore » of the plasma level corresponding to the frequency of the burst in the lower band should be consistent with the deprojected location of the leading edge (LE) of the associated CME; (2) the drift speed of the type II bursts derived from such a model should agree closely with the deprojected speed of the LE of the corresponding CMEs. With the above conditions, we find that: (1) the estimated field strengths are unique to each type II burst, and (2) the radial variation of the field strength in the different events indicate a pattern. It is steepest for the case where the heliocentric distance range over which the associated burst is observed is closest to the Sun, and vice versa.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..APR.R1045C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..APR.R1045C">Detecting special nuclear material using a neutron time projection chamber</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Carosi, G.; Bernstein, A.; Bowden, N.; Burke, J.; Carter, D.; Foxe, M.; Heffner, M.; Jovanovic, I.; Mintz, J.; O'Malley, P. 2010-02-01 Time projection chambers are 3-dimensional charged particle cameras based on drifting ionization tracks at a known velocity onto an electronic readout plane. These instruments are capable of detecting fast neutrons which are unique signatures of special nuclear material with low natural background rates. Here we describe a neutron Time Projection Chamber (nTPC) developed at Lawrence Livermore National Laboratory (LLNL) which has demonstrated directional sensitivity to fission neutrons along with high rejection of background gamma-ray and electron events. Using a combination hydrogen/methane drift gas at several atmospheres we've demonstrated the ability to point to a Cf-252 source simulating 6kg of weapons grade plutonium at 10's of meters with one hour integration time. Plans for future field deployable devices will also be outlined. ) </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1176218','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1176218">Three-dimensional, position-sensitive radiation detection</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> He, Zhong; Zhang, Feng 2010-04-06 Disclosed herein is a method of determining a characteristic of radiation detected by a radiation detector via a multiple-pixel event having a plurality of radiation interactions. The method includes determining a cathode-to-anode signal ratio for a selected interaction of the plurality of radiation interactions based on electron drift time data for the selected interaction, and determining the radiation characteristic for the multiple-pixel event based on both the cathode-to-anode signal ratio and the electron drift time data. In some embodiments, the method further includes determining a correction factor for the radiation characteristic based on an interaction depth of the plurality of radiation interactions, a lateral distance between the selected interaction and a further interaction of the plurality of radiation interactions, and the lateral positioning of the plurality of radiation interactions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018TCry...12..935R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018TCry...12..935R">Impact of rheology on probabilistic forecasts of sea ice trajectories: application for search and rescue operations in the Arctic</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Rabatel, Matthias; Rampal, Pierre; Carrassi, Alberto; Bertino, Laurent; Jones, Christopher K. R. T. 2018-03-01 We present a sensitivity analysis and discuss the probabilistic forecast capabilities of the novel sea ice model neXtSIM used in hindcast mode. The study pertains to the response of the model to the uncertainty on winds using probabilistic forecasts of ice trajectories. neXtSIM is a continuous Lagrangian numerical model that uses an elasto-brittle rheology to simulate the ice response to external forces. The sensitivity analysis is based on a Monte Carlo sampling of 12 members. The response of the model to the uncertainties is evaluated in terms of simulated ice drift distances from their initial positions, and from the mean position of the ensemble, over the mid-term forecast horizon of 10 days. The simulated ice drift is decomposed into advective and diffusive parts that are characterised separately both spatially and temporally and compared to what is obtained with a free-drift model, that is, when the ice rheology does not play any role in the modelled physics of the ice. The seasonal variability of the model sensitivity is presented and shows the role of the ice compactness and rheology in the ice drift response at both local and regional scales in the Arctic. Indeed, the ice drift simulated by neXtSIM in summer is close to the one obtained with the free-drift model, while the more compact and solid ice pack shows a significantly different mechanical and drift behaviour in winter. For the winter period analysed in this study, we also show that, in contrast to the free-drift model, neXtSIM reproduces the sea ice Lagrangian diffusion regimes as found from observed trajectories. The forecast capability of neXtSIM is also evaluated using a large set of real buoy's trajectories and compared to the capability of the free-drift model. We found that neXtSIM performs significantly better in simulating sea ice drift, both in terms of forecast error and as a tool to assist search and rescue operations, although the sources of uncertainties assumed for the present experiment are not sufficient for complete coverage of the observed IABP positions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JKPS...72..669X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JKPS...72..669X">Fishbone Oscillations in the Experimental Advanced Superconductivity Tokamak</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Xu, Li-Qing; Hu, Li-Qun; Yuan, Yi; Li, Ying-Ying; Zhong, Guo-Qiang; Liu, Hai-Qing; Chen, Kai-Yun; Shi, Tong-Hui; Duan, Yan-Min 2018-03-01 A fishbone oscillation was observed in the neutral beam injection plasma at Experimental Advanced Superconductivity Tokamak (EAST). This m = 1/n = 1 ( m, n: poloidal, toroidal mode numbers, respectively) typical internal kink mode travels in the ion-diamagnetism direction in the poloidal section with a rotation speed close to the ion diamagnetic drift frequency. A high thermal plasma beta and high amounts of energetic ions are necessary for the mode to develop. Fishbone oscillations can expel heavy impurities in the core, which favors sustaining a high-performance plasma. The born frequency of the fishbone oscillation is the ion diamagnetic drift frequency and the chirping down of the frequency during the initial growth phase is the result of a drop in iondiamagnetic drift frequency. The excitation energy is thought to be due to the thermal plasma pressure gradient; however, the development of a fishbone oscillation is related to energetic ions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14683056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14683056">Drift-wave turbulence and zonal flow generation.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Balescu, R 2003-10-01 Drift-wave turbulence in a plasma is analyzed on the basis of the wave Liouville equation, describing the evolution of the distribution function of wave packets (quasiparticles) characterized by position x and wave vector k. A closed kinetic equation is derived for the ensemble-averaged part of this function by the methods of nonequilibrium statistical mechanics. It has the form of a non-Markovian advection-diffusion equation describing coupled diffusion processes in x and k spaces. General forms of the diffusion coefficients are obtained in terms of Lagrangian velocity correlations. The latter are calculated in the decorrelation trajectory approximation, a method recently developed for an accurate measure of the important trapping phenomena of particles in the rugged electrostatic potential. The analysis of individual decorrelation trajectories provides an illustration of the fragmentation of drift-wave structures in the radial direction and the generation of long-wavelength structures in the poloidal direction that are identified as zonal flows. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFMSM51A0797C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFMSM51A0797C">Simulations of Plasmasheet Electrons in a Model Magnetosphere with AMIE Potentials: Implications for Diffuse Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chen, M. W.; Schulz, M.; Lu, G. 2001-12-01 We obtain distributions of precipitating electrons by tracing drift shells of plasmasheet electrons in the limit of strong pitch angle diffusion in Dungey's model magnetosphere, which consists of a dipolar magnetic field plus a uniform southward field. Under strong pitch-angle diffusion particles drift so as to conserve an adiabatic invariant Λ equal to the enclosed phase-space volume (i.e., the cube of the particle momentum p times the occupied flux-tube volume per unit magnetic flux). In the past we applied a quiescent Stern-Volland electric-field model with a cross-tail potential drop of 25 kV and added to it a storm-associated Brice-Nishida cross-magnetospheric electric field with impulses to represent substorm effects. For the present study we use the more realistic Assimilative Model of Ionospheric Electrodynamics (AMIE). We use an analytical expansion to express the AMIE ionospheric potential as a function of latitude and magnetic local time. We map this AMIE potential to latitudes >= 50^o to magnetospheric field lines with (L \\ge 2.5) in Dungey's magnetic field model. We trace the bounce-averaged drift motion of representative plasmasheet electrons for values of \\Lambda corresponding to energies of 0.25-64 keV on field lines of equatorial radial distance r = 6 R_E (L = 5.7), which maps to \\approx 65^o$ latitude in the ionosphere. We use the simulation results to map stormtime phase space distributions taking into account loss due to precipitation. We consider 2 models of electron scattering: (1) the limit of strong scattering everywhere, and (2) an MLT-dependent scattering that is less than everywhere strong in the plasma sheet. From the phase space distributions we calculate the total precipitating electron energy flux into the ionosphere. For this study we focus on the October 19, 1998, storm. We compare qualitatively the simulated energy flux with X-ray intensity from Polar/PIXIE images during this storm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.8300Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.8300Z">Physical mechanism causing rapid changes in ultrarelativistic electron pitch angle distributions right after a shock arrival: Evaluation of an electron dropout event</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhang, X.-J.; Li, W.; Thorne, R. M.; Angelopoulos, V.; Ma, Q.; Li, J.; Bortnik, J.; Nishimura, Y.; Chen, L.; Baker, D. N.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Blake, J. B.; Fennell, J. F. 2016-09-01 Three mechanisms have been proposed to explain relativistic electron flux depletions (dropouts) in the Earth's outer radiation belt during storm times: adiabatic expansion of electron drift shells due to a decrease in magnetic field strength, magnetopause shadowing and subsequent outward radial diffusion, and precipitation into the atmosphere (driven by EMIC wave scattering). Which mechanism predominates in causing electron dropouts commonly observed in the outer radiation belt is still debatable. In the present study, we evaluate the physical mechanism that may be primarily responsible for causing the sudden change in relativistic electron pitch angle distributions during a dropout event observed by Van Allen Probes during the main phase of the 27 February 2014 storm. During this event, the phase space density of ultrarelativistic (>1 MeV) electrons was depleted by more than 1 order of magnitude over the entire radial extent of the outer radiation belt (3 < L* < 5) in less than 6 h after the passage of an interplanetary shock. We model the electron pitch angle distribution under a compressed magnetic field topology based on actual solar wind conditions. Although these ultrarelativistic electrons exhibit highly anisotropic (peaked in 90°), energy-dependent pitch angle distributions, which appear to be associated with the typical EMIC wave scattering, comparison of the modeled electron distribution to electron measurements indicates that drift shell splitting is responsible for this rapid change in electron pitch angle distributions. This further indicates that magnetopause loss is the predominant cause of the electron dropout right after the shock arrival. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22482790-tandem-ion-mobility-spectrometry-coupled-laser-excitation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22482790-tandem-ion-mobility-spectrometry-coupled-laser-excitation"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Simon, Anne-Laure; Choi, Chang Min; Clavier, Christian This manuscript describes a new experimental setup that allows to perform tandem ion mobility spectrometry (IMS) measurements and which is coupled to a high resolution time-of-flight mass spectrometer. It consists of two 79 cm long drift tubes connected by a dual ion funnel assembly. The setup was built to permit laser irradiation of the ions in the transfer region between the two drift tubes. This geometry allows selecting ions according to their ion mobility in the first drift tube, to irradiate selected ions, and examine the ion mobility of the product ions in the second drift tube. Activation by collisionmore » is possible in the same region (between the two tubes) and between the second tube and the time-of-flight. IMS-IMS experiments on Ubiquitin are reported. We selected a given isomer of charge state +7 and explored its structural rearrangement following collisional activation between the two drift tubes. An example of IMS-laser-IMS experiment is reported on eosin Y, where laser irradiation was used to produce radical ions by electron photodetachment starting from doubly deprotonated species. This allowed measuring the collision cross section of the radical photo-product, which cannot be directly produced with an electrospray source.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015RScI...86i4101S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015RScI...86i4101S">Tandem ion mobility spectrometry coupled to laser excitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Simon, Anne-Laure; Chirot, Fabien; Choi, Chang Min; Clavier, Christian; Barbaire, Marc; Maurelli, Jacques; Dagany, Xavier; MacAleese, Luke; Dugourd, Philippe 2015-09-01 This manuscript describes a new experimental setup that allows to perform tandem ion mobility spectrometry (IMS) measurements and which is coupled to a high resolution time-of-flight mass spectrometer. It consists of two 79 cm long drift tubes connected by a dual ion funnel assembly. The setup was built to permit laser irradiation of the ions in the transfer region between the two drift tubes. This geometry allows selecting ions according to their ion mobility in the first drift tube, to irradiate selected ions, and examine the ion mobility of the product ions in the second drift tube. Activation by collision is possible in the same region (between the two tubes) and between the second tube and the time-of-flight. IMS-IMS experiments on Ubiquitin are reported. We selected a given isomer of charge state +7 and explored its structural rearrangement following collisional activation between the two drift tubes. An example of IMS-laser-IMS experiment is reported on eosin Y, where laser irradiation was used to produce radical ions by electron photodetachment starting from doubly deprotonated species. This allowed measuring the collision cross section of the radical photo-product, which cannot be directly produced with an electrospray source. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA515992','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA515992">Stimulated Electron Desorption Studies from Microwave Vacuum Electronics / High Power Microwave Materials</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2010-02-11 purchase a new gun. Mr. Mike Ackeret ( Transfer Engineering Inc.) Transfer Engineering’s expertise in specialty UHV work and machining propelled...modifications they helped design for the test stand. With UNLV guidance, Transfer Engineering designed and built the original UNLV SEE Test Stand...Staib electron gun, an isolated beam drift tube, a hexanode delay line with a chevron microchannel plate (MCP) stack, an isolated grid, an isolated </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PMB....59.5953M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PMB....59.5953M">Determination of relative ion chamber calibration coefficients from depth-ionization measurements in clinical electron beams</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Muir, B. R.; McEwen, M. R.; Rogers, D. W. O. 2014-10-01 A method is presented to obtain ion chamber calibration coefficients relative to secondary standard reference chambers in electron beams using depth-ionization measurements. Results are obtained as a function of depth and average electron energy at depth in 4, 8, 12 and 18 MeV electron beams from the NRC Elekta Precise linac. The PTW Roos, Scanditronix NACP-02, PTW Advanced Markus and NE 2571 ion chambers are investigated. The challenges and limitations of the method are discussed. The proposed method produces useful data at shallow depths. At depths past the reference depth, small shifts in positioning or drifts in the incident beam energy affect the results, thereby providing a built-in test of incident electron energy drifts and/or chamber set-up. Polarity corrections for ion chambers as a function of average electron energy at depth agree with literature data. The proposed method produces results consistent with those obtained using the conventional calibration procedure while gaining much more information about the behavior of the ion chamber with similar data acquisition time. Measurement uncertainties in calibration coefficients obtained with this method are estimated to be less than 0.5%. These results open up the possibility of using depth-ionization measurements to yield chamber ratios which may be suitable for primary standards-level dissemination. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811274S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811274S">Wind slab formation in snow: experimental setup and first results</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sommer, Christian; Lehning, Michael; Fierz, Charles 2016-04-01 The formation of wind-hardened surface layers, also known as wind slabs or wind crusts, is studied. Better knowledge about which processes and parameters are important will lead to an improved understanding of the mass balances in polar and alpine areas. It will also improve snow-cover models (i.e. SNOWPACK) as well as the forecast of avalanche danger. A ring-shaped wind tunnel has been built and instrumented. The facility is ring-shaped to simulate an infinitely long snow surface (infinite fetch). A SnowMicroPen (SMP) is used to measure the snow hardness. Other sensors measure environmental conditions such as wind velocity, air temperature, air humidity, the temperature of the snow and of the snow surface. A camera is used to detect drifting particles and to measure the Specific Surface Area (SSA) at the snow surface via near-infrared photography. First experiments indicate that mechanical fragmentation followed by sintering is the most efficient process to harden the surface. The hardness increased rapidly during drifting snow events, but only slowly or not at all when the wind speed was kept below the threshold for drifting snow. With drifting, the penetration resistance increased from the original 0.07 N to around 0.3 N in about an hour. Without drifting, a slow, further increase in resistance was observed. In about six hours, the hardness of the top 1-2 cm increased to 0.5 N. During this eight-hour experiment consisting of about two hours with intermittent drifting and six hours without drifting, the density at the surface increased from 66 kg/m3 to around 170 kg/m3. In the unaffected region close to the ground, the density increased from 100 kg/m3 to 110 kg/m3. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740026753','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740026753">Design and calibration of a rocket-borne electron spectrometer for investigation of particle ionization in the nighttime midlatitude E region</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Voss, H. D.; Smith, L. G. 1974-01-01 An explanation was developed for the formation, near midnight at midlatitudes, of a broad electron density layer extending approximately from 120 to 180 km and usually referred to as the intermediate E layer. The responsible mechanism is believed to be the converging vertical ion drifts resulting from winds of the solar semidiurnal tide. Numerical solutions of the continuity equation appropriate to the intermediate layer is described for particular models of ion drift, diffusion coefficents, and ionization production. Analysis of rocket observations of the layer show that the ionization rate is highly correlated with the planetary geomagnetic index, K sub p. Particle flux measurements support the idea that energetic electrons are the principal source of this ionization. A semiconductor spectrometer experiment for investigation of the particle flux, spectrum, and angular properties was designed and successfully flown on a Nike Apache rocket. A detailed description of the theory, design, and calibration of the experiment and some preliminary results presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003500&hterms=huang&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D30%26Ntt%3Dhuang','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003500&hterms=huang&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D30%26Ntt%3Dhuang">MMS Observations of Ion-Scale Magnetic Island in the Magnetosheath Turbulent Plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Huang, S. Y.; Sahraoui, F.; Retino, A.; Contel, O. Le; Yuan, Z. G.; Chasapis, A.; Aunai, N.; Breuillard, H.; Deng, X. H.; Zhou, M.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170003500'); toggleEditAbsImage('author_20170003500_show'); toggleEditAbsImage('author_20170003500_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170003500_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170003500_hide"> 2016-01-01 In this letter, first observations of ion-scale magnetic island from the Magnetospheric Multiscale mission in the magnetosheath turbulent plasma are presented. The magnetic island is characterized by bipolar variation of magnetic fields with magnetic field compression, strong core field, density depletion, and strong currents dominated by the parallel component to the local magnetic field. The estimated size of magnetic island is about 8 di, where di is the ion inertial length. Distinct particle behaviors and wave activities inside and at the edges of the magnetic island are observed: parallel electron beam accompanied with electrostatic solitary waves and strong electromagnetic lower hybrid drift waves inside the magnetic island and bidirectional electron beams, whistler waves, weak electromagnetic lower hybrid drift waves, and strong broadband electrostatic noise at the edges of the magnetic island. Our observations demonstrate that highly dynamical, strong wave activities and electron-scale physics occur within ion-scale magnetic islands in the magnetosheath turbulent plasma.. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhPl...21i2119A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhPl...21i2119A">Coupled ion acoustic and drift waves in magnetized superthermal electron-positron-ion plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Adnan, Muhammad; Mahmood, S.; Qamar, Anisa 2014-09-01 Linear and nonlinear coupled drift-ion acoustic waves are investigated in a nonuniform magnetoplasma having kappa distributed electrons and positrons. In the linear regime, the role of kappa distribution and positron content on the dispersion relation has been highlighted; it is found that strong superthermality (low value of κ) and addition of positrons lowers the phase velocity via decreasing the fundamental scalelengths of the plasmas. In the nonlinear regime, first, coherent nonlinear structure in the form of dipoles and monopoles are obtained and the boundary conditions (boundedness) in the context of superthermality and positron concentrations are discussed. Second, in case of scalar nonlinearity, a Korteweg-de Vries-type equation is obtained, which admit solitary wave solution. It is found that both compressive and rarefactive solitons are formed in the present model. The present work may be useful to understand the low frequency electrostatic modes in inhomogeneous electron positron ion plasmas, which exist in astrophysical plasma situations such as those found in the pulsar magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003188&hterms=particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dparticle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003188&hterms=particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dparticle">Observations of Energetic Particle Escape at the Magnetopause: Early Results from the MMS Energetic Ion Spectrometer (EIS)</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cohen, I. J.; Mauk, B. H.; Anderson, B. J.; Westlake, J. H.; Sibeck, David Gary; Giles, Barbara L.; Pollock, C. J.; Turner, D. L.; Fennell, J. F.; Blake, J. B.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170003188'); toggleEditAbsImage('author_20170003188_show'); toggleEditAbsImage('author_20170003188_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170003188_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170003188_hide"> 2016-01-01 Energetic (greater than tens of keV) magnetospheric particle escape into the magnetosheath occurs commonly, irrespective of conditions that engender reconnection and boundary-normal magnetic fields. A signature observed by the Magnetospheric Multiscale (MMS) mission, simultaneous monohemispheric streaming of multiple species (electrons, H+, Hen+), is reported here as unexpectedly common in the dayside, dusk quadrant of the magnetosheath even though that region is thought to be drift-shadowed from energetic electrons. This signature is sometimes part of a pitch angle distribution evolving from symmetric in the magnetosphere, to asymmetric approaching the magnetopause, to monohemispheric streaming in the magnetosheath. While monohemispheric streaming in the magnetosheath may be possible without a boundary-normal magnetic field, the additional pitch angle depletion, particularly of electrons, on the magnetospheric side requires one. Observations of this signature in the dayside dusk sector imply that the static picture of magnetospheric drift-shadowing is inappropriate for energetic particle dynamics in the outer magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/21535145-wave-propagation-noncollisional-heating-neutral-loop-helicon-discharges','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21535145-wave-propagation-noncollisional-heating-neutral-loop-helicon-discharges">Wave propagation and noncollisional heating in neutral loop and helicon discharges</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Celik, Y.; Crintea, D. L.; Luggenhoelscher, D. 2011-02-15 Heating mechanisms in two types of magnetized low pressure rf (13.56 MHz) discharges are investigated: a helicon discharge and a neutral loop discharge. Radial B-dot probe measurements demonstrate that the neutral loop discharge is sustained by helicon waves as well. Axial B-dot probe measurements reveal standing wave and beat patterns depending on the dc magnetic field strength and plasma density. In modes showing a strong wave damping, the plasma refractive index attains values around 100, leading to electron-wave interactions. In strongly damped modes, the radial plasma density profiles are mainly determined by power absorption of the propagating helicon wave, whereasmore » in weakly damped modes, inductive coupling dominates. Furthermore, an azimuthal diamagnetic drift is identified. Measurements of the helicon wave phase demonstrate that initial plane wave fronts are bent during their axial propagation due to the inhomogeneous density profile. A developed analytical standing wave model including Landau damping reproduces very well the damping of the axial helicon wave field. This comparison underlines the theory whereupon Landau damping of electrons traveling along the field lines at speeds close to the helicon phase velocity is the main damping mechanism in both discharges.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPT10066J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPT10066J">What sets the minimum tokamak scrape-off layer width?</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Joseph, Ilon 2016-10-01 The heat flux width of the tokamak scrape-off layer is on the order of the poloidal ion gyroradius, but the ``heuristic drift'' physics model is still not completely understood. In the absence of anomalous transport, neoclassical transport sets the minimum width. For plateau collisionality, the ion temperature width is set by qρi , while the electron temperature width scales as the geometric mean q(ρeρi) 1 / 2 and is close to qρi in magnitude. The width is enhanced because electrons are confined by the sheath potential and have a much longer time to radially diffuse before escaping to the wall. In the Pfirsch-Schluter regime, collisional diffusion increases the width by the factor (qR / λ) 1 / 2 where qR is the connection length and λ is the mean free path. This qualitatively agrees with the observed transition in the scaling law for detached plasmas. The radial width of the SOL electric field is determined by Spitzer parallel and ``neoclassical'' radial electric conductivity and has a similar scaling to that for thermal transport. Prepared under US DOE contract DE-AC52-07NA27344. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active">21</li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active">22</li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27313000','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27313000">Implementation of a cryo-electron tomography tilt-scheme optimized for high resolution subtomogram averaging.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Hagen, Wim J H; Wan, William; Briggs, John A G 2017-02-01 Cryo-electron tomography (cryoET) allows 3D structural information to be obtained from cells and other biological samples in their close-to-native state. In combination with subtomogram averaging, detailed structures of repeating features can be resolved. CryoET data is collected as a series of images of the sample from different tilt angles; this is performed by physically rotating the sample in the microscope between each image. The angles at which the images are collected, and the order in which they are collected, together are called the tilt-scheme. Here we describe a "dose-symmetric tilt-scheme" that begins at low tilt and then alternates between increasingly positive and negative tilts. This tilt-scheme maximizes the amount of high-resolution information maintained in the tomogram for subsequent subtomogram averaging, and may also be advantageous for other applications. We describe implementation of the tilt-scheme in combination with further data-collection refinements including setting thresholds on acceptable drift and improving focus accuracy. Requirements for microscope set-up are introduced, and a macro is provided which automates the application of the tilt-scheme within SerialEM. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhPl...15l2103G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhPl...15l2103G">Gyrokinetic-water-bag modeling of low-frequency instabilities in a laboratory magnetized plasma column</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gravier, E.; Klein, R.; Morel, P.; Besse, N.; Bertrand, P. 2008-12-01 A new model is presented, named collisional-gyro-water-bag (CGWB), which describes the collisional drift waves and ion-temperature-gradient (ITG) instabilities in a plasma column. This model is based on the kinetic gyro-water-bag approach recently developed [P. Morel et al., Phys. Plasmas 14, 112109 (2007)] to investigate ion-temperature-gradient modes. In CGWB electron-neutral collisions have been introduced and are now taken into account. The model has been validated by comparing CGWB linear analysis with other models previously proposed and experimental results as well. Kinetic effects on collisional drift waves are investigated, resulting in a less effective growth rate, and the transition from collisional drift waves to ITG instability depending on the ion temperature gradient is studied. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NuPhS.248..134D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NuPhS.248..134D">Analysis and Characterization of the Mechanical Structure for the I-Tracker of the Mu2e Experiment</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> De Lorenzis, L.; Grancagnolo, F.; L'Erario, A.; Maffezzoli, A.; Miccoli, A.; Rella, S.; Spedicato, M.; Zavarise, G. 2014-03-01 The design of a tracking detector for electrons in a magnetic field consisting of a drift chamber is discussed. The chosen materials for its construction must be light to minimize the effects of the subatomic particles interactions with the chamber walls. Low-density materials and very thin wall thicknesses are therefore needed. From a mechanical engineering point of view, it is important to analyse the drift chamber structure and define the conditions to which it is subject in terms of both mechanical loads and geometric constraints. The analysis of the structural response of the drift chamber has been performed through the Finite Element Method (FEM) as implemented in the commercial software ANSYS and its interface for the analysis for composite structures ACP (Ansys Composite Pre/Post). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25430378','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25430378">Simultaneous use of camera and probe diagnostics to unambiguously identify and study the dynamics of multiple underlying instabilities during the route to plasma turbulence.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Thakur, S C; Brandt, C; Light, A; Cui, L; Gosselin, J J; Tynan, G R 2014-11-01 We use multiple-tip Langmuir probes and fast imaging to unambiguously identify and study the dynamics of underlying instabilities during the controlled route to fully-developed plasma turbulence in a linear magnetized helicon plasma device. Langmuir probes measure radial profiles of electron temperature, plasma density and potential; from which we compute linear growth rates of instabilities, cross-phase between density and potential fluctuations, Reynold's stress, particle flux, vorticity, time-delay estimated velocity, etc. Fast imaging complements the 1D probe measurements by providing temporally and spatially resolved 2D details of plasma structures associated with the instabilities. We find that three radially separated plasma instabilities exist simultaneously. Density gradient driven resistive drift waves propagating in the electron diamagnetic drift direction separate the plasma into an edge region dominated by strong, velocity shear driven Kelvin-Helmholtz instabilities and a central core region which shows coherent Rayleigh-Taylor modes propagating in the ion diamagnetic drift direction. The simultaneous, complementary use of both probes and camera was crucial to identify the instabilities and understand the details of the very rich plasma dynamics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/1361823-understanding-impact-insulating-conducting-endplate-boundary-conditions-turbulence-csdx-through-nonlocal-simulations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1361823-understanding-impact-insulating-conducting-endplate-boundary-conditions-turbulence-csdx-through-nonlocal-simulations"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Vaezi, P.; Holland, C.; Thakur, S. C. The Controlled Shear Decorrelation Experiment (CSDX) linear plasma device provides a unique platform for investigating the underlying physics of self-regulating drift-wave turbulence/zonal flow dynamics. A minimal model of 3D drift-reduced nonlocal cold ion fluid equations which evolves density, vorticity, and electron temperature fluctuations, with proper sheath boundary conditions, is used to simulate dynamics of the turbulence in CSDX and its response to changes in parallel boundary conditions. These simulations are then carried out using the BOUndary Turbulence (BOUT++) framework and use equilibrium electron density and temperature profiles taken from experimental measurements. The results show that density gradient-driven drift-waves are themore » dominant instability in CSDX. However, the choice of insulating or conducting endplate boundary conditions affects the linear growth rates and energy balance of the system due to the absence or addition of Kelvin-Helmholtz modes generated by the sheath-driven equilibrium E × B shear and sheath-driven temperature gradient instability. Moreover, nonlinear simulation results show that the boundary conditions impact the turbulence structure and zonal flow formation, resulting in less broadband (more quasi-coherent) turbulence and weaker zonal flow in conducting boundary condition case. These results are qualitatively consistent with earlier experimental observations.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMSM12A..03N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMSM12A..03N">Equatorial measurement of SAID electric fields and relation with the plasmapause location</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nishimura, Y.; Wygant, J.; Ono, T.; Iizima, M.; Kumamoto, A.; Brautigam, D.; Rich, F. 2007-12-01 In order to investigate the equatorial source of subauroral ion drifts (SAID) and its association with the plasmapause position, multi-spacecraft measurements of SAID are presented using the CRRES, Akebono, and DMSP. Direct measurement of the convection electric field and plasmapause density close to the equator is measured by the electric field instrument onboard the CRRES satellite, and the plasmasheet electrons and low energy part of the ring current ions are measured by the low energy plasma instrument. The CRRES satellite is on the dusk inner magnetosphere, and the DMSP-F8 and Akebono satellites are approximately on the same field line. Associated with a substorm onset at 16:40 UT on February 20, 1991, the DMSP-F8 satellite at 19 MLT measures SAID with a maximum westward velocity of 1,500 m/s. The CRRES satellite is on outbound in the inner magnetosphere at ~21 MLT and ~5 RE at the onset of the substorm. It measures increase of DC electric field with 0.4 mV/m in the plasmasphere just after the substorm onset. Thirty minutes later, injection of ring current ions are observed in the plasmasphere with Bz decrease. After the crossing of the plasmapause, the electric field increases to 0.8 mV/m. At the same time, the spacecraft enters the plasmasheet, and the DC electric field disappears. The same time sequence is also identified in other SAID events detected on the dusk inner magnetosphere. The above CRRES measurement indicates that DC electric field is intensified in a narrow region between the ring current and electron plasmasheet after the onset of the substorm. Although the E*B drift points sunward in this region, this region with enhanced electric field is filled with plasmaspheric plasma without abrupt density change. The position where the convection electric field is equal to the corotation electric field locates inside the plasmapause. The plasmapause coincides with inner edge of the plasmasheet. This association suggests that the plasmaspheric plasma is depleted by the plasmasheet electrons, possibly by the enhanced E*B drift earthward of the plasmasheet. During the SAID event on 16:40 UT on February 20, 1991, the Akebono satellite was approximately on the same field line of the CRRES satellite (21 MLT and 5 RE) 40 minutes later the substorm onset. It measures enhancement of electric field with 2 mV/m between L=5 and 6. The inner edge of the electric field corresponds to the inner edge of ring current ions, and the outer edge coincides with the plasmasheet electrons. This signature of the electric field intensification in the charge-separated region is in accordance with the CRRES measurement. This study has clarified that the equatorial source of SAID electric fields is charge separation of ring current ions and plasmasheet electrons by electric field associated with substorms. This is consistent with the theoretical study by Southwood and Wolf [1978] and low-altitude measurements by Anderson et al. [2001] by that the charge separation provides current and voltage sources and the electric field is increased by the low conductance of the subauroral ionosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM43A2697P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM43A2697P">Quantifying the Precipitation Loss of Radiation Belt Electrons during a Rapid Dropout Event</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pham, K. H.; Tu, W.; Xiang, Z. 2017-12-01 Relativistic electron flux in the radiation belt can drop by orders of magnitude within the timespan of hours. In this study, we used the drift-diffusion model that includes azimuthal drift and pitch angle diffusion of electrons to simulate low-altitude electron distribution observed by POES/MetOp satellites for rapid radiation belt electron dropout event occurring on May 1, 2013. The event shows fast dropout of MeV energy electrons at L>4 over a few hours, observed by the Van Allen Probes mission. By simulating the electron distributions observed by multiple POES satellites, we resolve the precipitation loss with both high spatial and temporal resolution and a range of energies. We estimate the pitch angle diffusion coefficients as a function of energy, pitch angle, and L-shell, and calculate corresponding electron lifetimes during the event. The simulation results show fast electron precipitation loss at L>4 during the electron dropout, with estimated electron lifetimes on the order of half an hour for MeV energies. The electron loss rate show strong energy dependence with faster loss at higher energies, which suggest that this dropout event is dominated by quick and localized scattering process that prefers higher energy electrons. The estimated pitch angle diffusion rates from the model are then compared with in situ wave measurements from Van Allen Probes to uncover the underlying wave-particle-interaction mechanisms that are responsible for the fast electron precipitation. Comparing the resolved precipitation loss with the observed electron dropouts at high altitudes, our results will suggest the relative role of electron precipitation loss and outward radial diffusion to the radiation belt dropouts during storm and non-storm times, in addition to its energy and L dependence. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28429589','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28429589">Inhibition of Zero Drift in Perovskite-Based Photodetector Devices via [6,6]-Phenyl-C61-butyric Acid Methyl Ester Doping.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Liu, Yintao; Jia, Renxu; Wang, Yucheng; Hu, Ziyang; Zhang, Yuming; Pang, Tiqiang; Zhu, Yuejin; Luan, Suzhen 2017-05-10 Zero drift can severely deteriorate the stability of the light-dark current ratio, detectivity, and responsivity of photodetectors. In this paper, the effects of a [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-doped perovskite-based photodetector device on the inhibition of zero drift under dark state are discussed. Two kinds of photodetectors (Au/CH 3 NH 3 PbI x Cl 3-x /Au and Au/CH 3 NH 3 PbI x Cl 3-x :PCBM/Au) were prepared, and the materials and photodetector devices were measured by scanning electron microscopy, X-ray diffraction, photoluminescence, ultraviolet absorption spectra, and current-voltage and current-time measurements. It was found that similar merit parameters, including light-dark current ratio (∼10 2 ), detectivity (∼10 11 Jones), and responsivity were obtained for these two kinds of photodetectors. However, the drift of Au/CH 3 NH 3 PbI x Cl 3-x :PCBM/Au devices is negligible, while a drift of ∼0.2 V exists in Au/CH 3 NH 3 PbI x Cl 3-x /Au devices. A new model is proposed based on the hindering theory of ion (vacancy) migration, and it is believed that the dopant PCBM can hinder the ion (vacancy) migration of perovskite materials to suppress the phenomenon of zero drift in perovskite-based photodetectors. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA606338','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA606338">Electron Transport in Graphene From a Diffusion-Drift Perspective</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2010-02-24 Tung, M.E. Schwartz, M. Takita, Y.-J. Wang, P. Kim, and H.L. Stormer , “Cyclotron resonance in bilayer graphene,” Phys. Rev. Lett. 100, 087403 (2008...Dec. 2004. [3] K. I. Bolotin, K. J. Sikes, Z. Jiang, M. Klima, G. Fudenberg, J. Hone, P. Kim, and H. L. Stormer , “Ultrahigh electron mobility in </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM21A2549H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM21A2549H">Rapid acceleration of outer radiation belt electrons associated with solar wind pressure pulse: Simulation study with Arase and Van Allen Probe observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hayashi, M.; Yoshizumi, M.; Saito, S.; Matsumoto, Y.; Kurita, S.; Teramoto, M.; Hori, T.; Matsuda, S.; Shoji, M.; Machida, S.; Amano, T.; Seki, K.; Higashio, N.; Mitani, T.; Takashima, T.; Kasahara, Y.; Kasaba, Y.; Yagitani, S.; Ishisaka, K.; Tsuchiya, F.; Kumamoto, A.; Matsuoka, A.; Shinohara, I.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G. 2017-12-01 Relativistic electron fluxes of the outer radiation belt rapidly change in response to solar wind variations. One of the shortest acceleration processes of electrons in the outer radiation belt is wave-particle interactions between drifting electrons and fast-mode waves induced by compression of the dayside magnetopause caused by interplanetary shocks. In order to investigate this process by a solar wind pressure pulse, we perform a code-coupling simulation using the GEMSIS-RB test particle simulation (Saito et al., 2010) and the GEMSIS-GM global MHD magnetosphere simulation (Matsumoto et al., 2010). As a case study, an interplanetary pressure pulse with the enhancement of 5 nPa is used as the up-stream condition. In the magnetosphere, the fast mode waves with the azimuthal electric field ( negative 𝐸𝜙 : |𝐸&;#120601;| 10 mV/m, azimuthal mode number : m ≤ 2) propagates from the dayside to nightside, interacting with electrons. From the simulation results, we derived effective acceleration model and condition : The electrons whose drift velocities vd ≥ (π/2)Vfast are accelerated efficiently. On December 20, 2016, the Arase (ERG) satellite was launched , allowing more accurate multi-point simultaneous observation with other satellites. We will compare our simulation results with observations from Arase and Van Allen Probes, and investigate the acceleration condition of relativistic electrons associated with storm sudden commencement (SSC). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18723207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18723207">Field experiment on spray drift: deposition and airborne drift during application to a winter wheat crop.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Wolters, André; Linnemann, Volker; van de Zande, Jan C; Vereecken, Harry 2008-11-01 A field experiment was performed to evaluate various techniques for measuring spray deposition and airborne drift during spray application to a winter wheat crop. The application of a spraying agent containing the fluorescent dye Brilliant Sulfo Flavine by a conventional boom sprayer was done according to good agricultural practice. Deposition was measured by horizontal collectors in various arrangements in and outside the treated area. Airborne spray drift was measured both with a passive and an active air collecting system. Spray deposits on top of the treated canopy ranged between 68 and 71% of the applied dose and showed only small differences for various arrangements of the collectors. Furthermore, only small variations were measured within the various groups of collectors used for these arrangements. Generally, the highest spray deposition outside the treated area was measured close to the sprayed plot and was accompanied by a high variability of values, while a rapid decline of deposits was detected in more remote areas. Estimations of spray deposits with the IMAG Drift Calculator were in accordance with experimental findings only for areas located at a distance of 0.5-4.5 m from the last nozzle, while there was an overestimation of a factor of 4 at a distance of 2.0-3.0 m, thus revealing a high level of uncertainty of the estimation of deposition for short distances. Airborne spray drift measured by passive and active air collecting systems was approximately at the same level, when taking into consideration the collector efficiency of the woven nylon wire used as sampling material for the passive collecting system. The maximum value of total airborne spray drift for both spray applications (0.79% of the applied dose) was determined by the active collecting system. However, the comparatively high variability of measurements at various heights above the soil by active and passive collecting systems revealed need for further studies to elucidate the spatial pattern of airborne spray drift. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590910-heating-acceleration-solar-wind-ions-turbulent-wave-spectrum-inhomogeneous-expanding-plasma','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590910-heating-acceleration-solar-wind-ions-turbulent-wave-spectrum-inhomogeneous-expanding-plasma">Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ofman, Leon, E-mail: Leon.Ofman@nasa.gov; NASA Goddard Space Flight Center, Greenbelt, MD; Visiting, Department of Geosciences, Tel Aviv University, Tel Aviv Near the Sun (< 10R{sub s}) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects ofmore » background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22591769-cdznte-position-sensitive-drift-detectors-thicknesses-up','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22591769-cdznte-position-sensitive-drift-detectors-thicknesses-up"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Bolotnikov, A. E., E-mail: bolotnik@bnl.gov; Camarda, G. S.; Cui, Y. We investigated the feasibility of long-drift-time CdZnTe (CZT) gamma-ray detectors, fabricated from CZT material produced by Redlen Technologies. CZT crystals with cross-section areas of 5 × 5 mm{sup 2} and 6 × 6 mm{sup 2} and thicknesses of 20-, 30-, 40-, and 50-mm were configured as 3D position-sensitive drift detectors and were read out using a front-end ASIC. By correcting the electron charge losses caused by defects in the crystals, we demonstrated high performance for relatively thick detectors fabricated from unselected CZT material. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950036420&hterms=rosenberg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drosenberg','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950036420&hterms=rosenberg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drosenberg">High frequency drift instabilities in a dusty plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rosenberg, M.; Krall, N. A. 1994-01-01 High frequency drift instabilities with omega(sub ce) much greater than omega which is greater than omega(sub ci) are investigated in a dusty magnetized plasma in which locally there is an electron density gradient which is opposite in sign to a dust density gradient. Two different equilibria are considered, characterized by rho(sub d) greater than L(sub d) and less than L(sub d), where rho(sub d) is the dust gyroradius and L(sub nd) is the dust density scale length. Possible application to Saturn's F-ring is discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/1008172-gluex-central-drift-chamber-design-performance','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1008172-gluex-central-drift-chamber-design-performance">The GlueX central drift chamber: Design and performance</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Van Haarlem, Y; Barbosa, F; Dey, B 2010-10-01 Tests and studies concerning the design and performance of the GlueX Central Drift Chamber (CDC) are presented. A full-scale prototype was built to test and steer the mechanical and electronic design. Small scale prototypes were constructed to test for sagging and to do timing and resolution studies of the detector. These studies were used to choose the gas mixture and to program a Monte Carlo simulation that can predict the detector response in an external magnetic field. Particle identification and charge division possibilities were also investigated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.474..115H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.474..115H">Kinetic Theory and Fast Wind Observations of the Electron Strahl</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Horaites, Konstantinos; Boldyrev, Stanislav; Wilson, Lynn B., III; Viñas, Adolfo F.; Merka, Jan 2018-02-01 We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centred on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature and the magnetic field strength decline as power laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with observations of the eVDF made by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 au, in particular by predicting how this width scales with particle energy and background density. We find that the strahl distribution is largely determined by the local temperature Knudsen number γ ∼ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 au; however, it then overestimates the strahl amplitude at larger heliocentric distances. This indicates that our model may be improved through the inclusion of additional physics, possibly through the introduction of 'anomalous diffusion' of the strahl electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......184H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......184H">Physics of the current injection process during localized helicity injection</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hinson, Edward Thomas An impedance model has been developed for the arc-plasma cathode electron current source used in localized helicity injection tokamak startup. According to this model, a potential double layer (DL) is established between the high-density arc plasma (narc ˜ 1021 m-3) in the electron source, and the less-dense external tokamak edge plasma (nedge ˜ 10 18 m-3) into which current is injected. The DL launches an electron beam at the applied voltage with cross-sectional area close to that of the source aperture: Ainj ≈ 2 cm 2. The injected current, Iinj, increases with applied voltage, Vinj, according to the standard DL scaling, Iinj ˜ V(3/2/ inj), until the more restrictive of two limits to beam density nb arises, producing Iinj ˜ V(1/2/inj), a scaling with beam drift velocity. For low external tokamak edge density nedge, space-charge neutralization of the intense electron beam restricts the injected beam density to nb ˜ nedge. At high Jinj and sufficient edge density, the injected current is limited by expansion of the DL sheath, which leads to nb ˜ narc. Measurements of narc, Iinj , nedge, Vinj, support these predicted scalings, and suggest narc as a viable control actuator for the source impedance. Magnetic probe signals ≈ 300 degrees toroidally from the injection location are consistent with expectations for a gyrating, coherent electron beam with a compact areal cross-section. Technological development of the source has allowed an extension of the favorable Iinj ˜ V(1/2/inj) to higher power without electrical breakdown. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1224050-determination-equilibrium-electron-temperature-times-using-electron-swarm-model-bolsig+-calculated-collision-frequencies-rate-coefficients','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1224050-determination-equilibrium-electron-temperature-times-using-electron-swarm-model-bolsig+-calculated-collision-frequencies-rate-coefficients">Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; ... 2015-08-04 Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Importantmore » swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8662584','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8662584">Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Sereno; Dutheil; Iarochene; Larsson; Lyon; Magwene; Sidor; Varricchio; Wilson 1996-05-17 Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15893364','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15893364">Metsulfuron spray drift reduces fruit yield of hawthorn (Crataegus monogyna L.).</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Kjaer, Christian; Strandberg, Morten; Erlandsen, Mogens 2006-03-01 This study was carried out to investigate whether spray drift of metsulfuron has a potential to negatively affect hawthorn (Crataegus monogyna) hedgerows near agricultural fields. For this purpose four doses of metsulfuron ranging from 5% to 40% of the field dose (4 g metsulfuron per hectare) were sprayed on trees in seven different hawthorn hedgerows. The actual deposition on the leaves was measured by means of a tracer (glycine). Spraying was conducted both at the bud stage and at early flowering. Leaves, flowers, green berries and mature berries were harvested and the number and weight of each were measured. The spraying at the bud stage caused a highly significant reduction in number and dry weight of berries, whereas it had no effects on leaf and flower production. The berry reduction was close to 100% at actual depositions relevant for spray drift under normal conditions. Spraying at early flowering also significantly reduced berries although the effect was smaller than for the spraying at bud stage. The early flower stage spraying caused no reduction in number and size of leaves. The possible ecological consequence is that metsulfuron spray drift from agricultural fields has a potential to reduce the amount of berries available for frugivorous birds in nearby hedgerows. A potential need for regulatory measures to reduce herbicide spray drift to hedgerows situated near agricultural fields with herbicide use is also indicated. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active">22</li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active">23</li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19710000089','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19710000089">Polarographic carbon dioxide transducer amplifier</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Stillman, G. 1971-01-01 Electronic amplifier contains matched pair of metal oxide semiconductor field effect transistor devices which have high input impedance and long-term stability. Thermistor in feedback loop provides temperature compensation for large drifts in the sensor. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000APS..DPPHM1003L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000APS..DPPHM1003L">Plasma Instabilities in Hall Thrusters</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Litvak, Andrei A.; Fisch, Nathaniel J. 2000-10-01 We describe theoretically waves in the channel of a Hall thruster, propagating transversely to the accelerated ion flow. In slab geometry, a two-fluid hydrodynamic theory with collisional terms shows that azimuthal lower-hybrid and Alfven waves will be unstable due to electron collisions in the presence of ExB drift. In addition, plasma inhomogeneities can drive other instabilities that can be analyzed through a dispersion relation in the well-known form of the Rayleigh equation. An instability condition is derived for azimuthal electrostatic waves, synchronized with the electron drift flow. Propagation with nonzero wavenumber along the magnetic field is also studied. Thus, several different aspects of wave propagation during thruster operation are explored. These waves may be important to understand and possibly to control in view of the possible influence of thruster electromagnetic effects on communication signal propagation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdSpR..59.2679S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdSpR..59.2679S">Stability of the magnetosonic wave in a cometary multi-ion plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sreekala, G.; Varghese, Anu; Jayakumar, Neethu; Michael, Manesh; Sebastian, Sijo; Venugopal, Chandu 2017-05-01 A generalized dispersion relation of the magnetosonic wave in a four component plasma consisting of electrons and hydrogen ions of solar origin and positively and negatively charged oxygen ions of cometary origin has been derived by using the Vlasov-Maxwell kinetic model. Parallel to the magnetic field, the hydrogen and electron components are modeled by a drifting Maxwellian distribution; perpendicular to the magnetic field, we use a loss cone type distribution obtained by the subtraction of two Maxwellian distributions having different temperatures. The effect of change in the drift velocity of streaming components and number densities and temperatures of each species in driving the instability has been analyzed both analytically and numerically. For typical parameters at comet Halley, we find that both positively and negatively charged oxygen ions can drive the wave unstable. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/674793','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/674793">Studies of beam position monitor stability</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Tenenbaum, P. 1998-05-01 The authors present the results from two studies of the time stability between the mechanical center of a beam position monitor and its electrical/electronic center. In the first study, a group of 93 BPM processors was calibrated via Test Pulse Generator once per hour in order to measure the contribution of the readout electronics to offset drifts. In the second study, a triplet of stripline BPMs in the Final Focus Test Beam, separated only by drift spaces, was read out every 6 minutes during 1 week of beam operation. In both cases offset stability was observed to be on themore » order of microns over time spans ranging from hours to days, although during the beam study much worse performance was also observed. Implications for the beam position monitor system of future linear collider systems are discussed.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.P51F..03R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.P51F..03R">Icy Moon Absorption Signatures: Probes of Saturnian Magnetospheric Dynamics and Moon Activity</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Roussos, E.; Krupp, N.; Jones, G. H.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Motschmann, U.; Dougherty, M. K.; Lagg, A.; Woch, J. 2006-12-01 After the first flybys at the outer planets by the Pioneer and Voyager probes, it became evident that energetic charged particle absorption features in the radiation belts are important tracers of magnetospheric dynamical features and parameters. Absorption signatures are especially important for characterizing the Saturnian magnetosphere. Due to the spin and magnetic axes' near-alignment, losses of particles to the icy moon surfaces and rings are higher compared to the losses at other planetary magnetospheres. The refilling rate of these absorption features (termed "micorsignatures") can be associated with particle diffusion. In addition, as these microsignatures drift with the properties of the pre-depletion electrons, they provide us direct information on the drift shell structure in the radiation belts and the factors that influence their shape. The multiple icy moon L-shell crossings by the Cassini spacecraft during the first 2 years of the mission provided us with almost 100 electron absorption events by eight different moons, at various longitudinal separations from each one and at various electron energies. Their analysis seems to give a consistent picture of the electron diffusion source and puts aside a lot of inconsistencies that resulted from relevant Pioneer and Voyager studies. The presence of non-axisymmetric particle drift shells even down to the orbit of Enceladus (3.98 Rs), also revealed through this analysis, suggests either large ring current disturbances or the action of global or localized electric fields. Finally, despite these absorption signatures being observed far from the originating moons, they can give us hints on the nature of the local interaction between each moon and the magnetospheric plasma. It is, nevertheless, beyond any doubt that energetic charged particle absorption signatures are a very powerful tool that can be used to effectively probe a series of dynamical processes in the Saturnian magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950059022&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DPlasma%2BRing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950059022&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DPlasma%2BRing">Decay of equatorial ring current ions and associated aeronomical consequences</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Fok, M.-C.; Kozyra, J. U.; Nagy, A. F.; Rasmussen, C. E.; Khazanov, G. V. 1993-01-01 The decay of the major ion species which constitute the ring current is studied by solving the time evolution of their distribution functions during the recovery phase of a moderate geomagnetic storm. In this work, only equatorially mirroring particles are considered. Particles are assumed to move subject to E x B and gradient drifts. They also experience loses along their drift paths. Two loss mechanisms are considered: charge exchange with neutral hydrogen atoms and Coulomb collisions with thermal plasma in the plasmasphere. Thermal plasma densities are calculated with a plasmaspheric model employing a time-dependent convection electric field model. The drift-loss model successfully reproduces a number of important and observable features in the distribution function. Charge exchange is found to be the major loss mechanism for the ring current ions; however the important effects of Coulomb collisions on both the ring current and thermal populations are also presented. The model predicts the formation of a low-energy (less than 500 eV) ion population as a result of energy degradation caused by Coulomb collision of the ring current ions with the plasmaspheric electrons; this population may be one source of the low-energy ions observed during active and quiet periods in the inner magnetosphere. The energy transferred to plasmaspheric electrons through Coulomb collisions with ring current ions is believed to be the energy source for the electron temperature enhancement and the associated 6300 A (stable auroral red (SAR) arc) emission in the subauroral region. The calculated energy deposition rate is sufficient to produce a subauroral electron temperature enhancement and SAR arc emissions that are consistent with observations of these quantities during moderate magnetic activity levels. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05573&hterms=fine+dust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dfine%2Bdust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05573&hterms=fine+dust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dfine%2Bdust">Drifts of Dust or Something Else?</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 2004-01-01 While the interior and far walls of the crater dubbed 'Bonneville' can be seen in the background, the dominant foreground features in this 180-degree navigation camera mosaic are the wind-deposited drifts of dust or sand. NASA's Mars Exploration Rover Spirit completed this mosaic on sol 71, March 15, 2004, from its newest location at the rim of 'Bonneville' crater. Scientists are interested in these formations in part because they might give insight into the processes that formed some of the material within the crater. Thermal emission measurements by the rover indicate that the dark material just below the far rim of this crater is spectrally similar to rocks that scientists have analyzed along their journey to this location. They want to know why this soil-like material has a spectrum that more closely resembles rocks rather than other soils examined so far. The drifts seen in the foreground of this mosaic might have the answer. Scientists hypothesize that these drifts might consist of wind-deposited particles that are the same as the dark material found against the back wall of the crater. If so, Spirit may spend time studying the material and help scientists understand why it is different from other fine-grained material seen at Gusev. The drifts appear to be lighter in color than the dark material deposited on the back wall of the crater. They might be covered by a thin deposit of martian dust, or perhaps the drift is like other drifts seen during Spirit's journey and is just a collection of martian dust. To find out, Spirit will spend some of sol 72 digging its wheels into the drift to uncover its interior. After backing up a bit, Spirit will use the panoramic camera and miniature thermal emission spectrometer to analyze the scuffed area. If the interior material has a similar spectrum to the dark deposit in the crater, then Spirit will most likely stay here a little longer to study the drift with the instruments on its robotic arm. If the material is uniform - that is, dusty all the way down, Spirit will most likely move off to another target. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19953149','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19953149">Closed-loop carrier-envelope phase stabilization with an acousto-optic programmable dispersive filter.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Forget, N; Canova, L; Chen, X; Jullien, A; Lopez-Martens, R 2009-12-01 We demonstrate arbitrary carrier-envelope (CE) phase control of femtosecond laser pulses by an acousto-optic programmable dispersive filter (AOPDF), with an accuracy better than pi/100 at a repetition rate of 1 kHz. We also demonstrate, for the first time to the best of our knowledge, 15 Hz closed-loop CE phase stabilization using an AOPDF inside a 1 kHz chirped pulse amplifier to correct for slow CE phase drifts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://pubs.usgs.gov/wsp/2333/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/wsp/2333/report.pdf">Tritium migration from a low-level radioactive-waste disposal site near Chicago, Illinois</a> <a target="_blank" rel="noopener noreferrer" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a> Nicholas, J.R.; Healy, R.W. 1988-01-01 This paper describes the results of a study to determine the geologic and hydrologic factors that control migration of tritium from a closed, low-level radioactive-waste disposal site. The disposal site, which operated from 1943 to mid1949, contains waste generated by research activities at the world's first nuclear reactors. Tritium has migrated horizontally at least 1,300 feet northward in glacial drift and more than 650 feet in the underlying dolomite. Thin, gently sloping sand layers in an otherwise clayey glacial drift are major conduits for ground-water flow and tritium migration in a perched zone beneath the disposal site. Tritium concentrations in the drift beneath the disposal site exceed 100,000 nanocuries per liter. Regional horizontal joints in the dolomite are enlarged by solution and are the major conduits for ground-water flow and tritium migration in the dolomite. A weathered zone at the top of the dolomite also is a pathway for tritium migration. The maximum measured tritium concentration in the dolomite is 29.4 nanocuries per liter. Fluctuations of tritium concentration in the dolomite are the result of dilution by seasonal recharge from the drift. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM43A2289L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM43A2289L">Magnetopause Losses of Radiation Belt Electrons During a Recent Magnetic Storm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lemon, C. L.; Chen, M.; Roeder, J. L.; Fennell, J. F.; Mulligan, T. L.; Claudepierre, S. G. 2013-12-01 We present results from Van Allen Probes observations during the magnetic storm of June 1, 2013, and compare them with simulations of the same event using the RCM-E model. The RCM-E calculates ion and electron transport in self-consistently computed electric and magnetic fields. We examine the effect of the perturbed ring current magnetic field on the transport of energetic electrons, and the significance of this transport for explaining the observed evolution of radiation belt fluxes during this event. The event is notable because it is a relatively simple storm in which strong convection persists for approximately 7 hours, injecting a moderately strong ring current (minimum Dst of -120 nT); convection then quickly shuts off, leading to a long and smooth recovery phase. We use RCM-E simulations, constrained by Van Allen Probes data, to asses the rate of magnetopause losses of electrons (magnetopause shadowing), and to calculate electron drift times and the evolution of electron phase space densities during the storm event. We recently modified the RCM-E plasma drift calculations to include relativistic treatment of electrons and a more realistic electron loss model. The new electron loss model, although still somewhat simplistic, gives much more accurate loss rates in the inner magnetosphere (including the radiation belts), which significantly affects the resulting electron fluxes compared to previous simulations. This, in turn, modifies the transport of ions and electrons via feedback with both the electric and magnetic fields. Our results highlight the effect of the ring current on the evolution of the radiation belt electrons, with particular emphasis on the role that magnetopause losses play in the observed variation of radiation belt electron fluxes during the storm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33A2765H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33A2765H">Kinetic Theory and Fast Wind Observations of the Electron Strahl</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Horaites, K.; Boldyrev, S.; Wilson, L. B., III; Figueroa-Vinas, A.; Merka, J. 2017-12-01 We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centered on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature, and the strength of the magnetic field decline as power-laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with the observations. To this end, we compare our model with the eVDF measured by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 AU, in particular by predicting how this width scales with particle energy and background density. We find the shape of the strahl distribution is largely determined by the local temperature Knudsen number γ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 AU; however, it then overestimates the strahl amplitude compared to the amplitude of the electron core at larger heliocentric distances. This indicates that our model may need to be improved through the inclusion of additional physics, possibly through the introduction of "anomalous diffusion" of the strahl electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25f1204B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25f1204B">E × B electron drift instability in Hall thrusters: Particle-in-cell simulations vs. theory</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Boeuf, J. P.; Garrigues, L. 2018-06-01 The E × B Electron Drift Instability (E × B EDI), also called Electron Cyclotron Drift Instability, has been observed in recent particle simulations of Hall thrusters and is a possible candidate to explain anomalous electron transport across the magnetic field in these devices. This instability is characterized by the development of an azimuthal wave with wavelength in the mm range and velocity on the order of the ion acoustic velocity, which enhances electron transport across the magnetic field. In this paper, we study the development and convection of the E × B EDI in the acceleration and near plume regions of a Hall thruster using a simplified 2D axial-azimuthal Particle-In-Cell simulation. The simulation is collisionless and the ionization profile is not-self-consistent but rather is given as an input parameter of the model. The aim is to study the development and properties of the instability for different values of the ionization rate (i.e., of the total ion production rate or current) and to compare the results with the theory. An important result is that the wavelength of the simulated azimuthal wave scales as the electron Debye length and that its frequency is on the order of the ion plasma frequency. This is consistent with the theory predicting destruction of electron cyclotron resonance of the E × B EDI in the non-linear regime resulting in the transition to an ion acoustic instability. The simulations also show that for plasma densities smaller than under nominal conditions of Hall thrusters the field fluctuations induced by the E × B EDI are no longer sufficient to significantly enhance electron transport across the magnetic field, and transit time instabilities develop in the axial direction. The conditions and results of the simulations are described in detail in this paper and they can serve as benchmarks for comparisons between different simulation codes. Such benchmarks would be very useful to study the role of numerical noise (numerical noise can also be responsible to the destruction of electron cyclotron resonance) or the influence of the period of the azimuthal domain, as well as to reach a better and consensual understanding of the physics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhRvS...9i0401S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhRvS...9i0401S">Analytic model of a magnetically insulated transmission line with collisional flow electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stygar, W. A.; Wagoner, T. C.; Ives, H. C.; Corcoran, P. A.; Cuneo, M. E.; Douglas, J. W.; Gilliland, T. L.; Mazarakis, M. G.; Ramirez, J. J.; Seamen, J. F.; Seidel, D. B.; Spielman, R. B. 2006-09-01 We have developed a relativistic-fluid model of the flow-electron plasma in a steady-state one-dimensional magnetically insulated transmission line (MITL). The model assumes that the electrons are collisional and, as a result, drift toward the anode. The model predicts that in the limit of fully developed collisional flow, the relation between the voltage Va, anode current Ia, cathode current Ik, and geometric impedance Z0 of a 1D planar MITL can be expressed as Va=IaZ0h(χ), where h(χ)≡[(χ+1)/4(χ-1)]1/2-ln⁡⌊χ+(χ2-1)1/2⌋/2χ(χ-1) and χ≡Ia/Ik. The relation is valid when Va≳1MV. In the minimally insulated limit, the anode current Ia,min⁡=1.78Va/Z0, the electron-flow current If,min⁡=1.25Va/Z0, and the flow impedance Zf,min⁡=0.588Z0. {The electron-flow current If≡Ia-Ik. Following Mendel and Rosenthal [Phys. Plasmas 2, 1332 (1995)PHPAEN1070-664X10.1063/1.871345], we define the flow impedance Zf as Va/(Ia2-Ik2)1/2.} In the well-insulated limit (i.e., when Ia≫Ia,min⁡), the electron-flow current If=9Va2/8IaZ02 and the flow impedance Zf=2Z0/3. Similar results are obtained for a 1D collisional MITL with coaxial cylindrical electrodes, when the inner conductor is at a negative potential with respect to the outer, and Z0≲40Ω. We compare the predictions of the collisional model to those of several MITL models that assume the flow electrons are collisionless. We find that at given values of Va and Z0, collisions can significantly increase both Ia,min⁡ and If,min⁡ above the values predicted by the collisionless models, and decrease Zf,min⁡. When Ia≫Ia,min⁡, we find that, at given values of Va, Z0, and Ia, collisions can significantly increase If and decrease Zf. Since the steady-state collisional model is valid only when the drift of electrons toward the anode has had sufficient time to establish fully developed collisional flow, and collisionless models assume there is no net electron drift toward the anode, we expect these two types of models to provide theoretical bounds on Ia, If, and Zf. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApPhL.105c3512L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApPhL.105c3512L">Role of the dielectric for the charging dynamics of the dielectric/barrier interface in AlGaN/GaN based metal-insulator-semiconductor structures under forward gate bias stress</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lagger, P.; Steinschifter, P.; Reiner, M.; Stadtmüller, M.; Denifl, G.; Naumann, A.; Müller, J.; Wilde, L.; Sundqvist, J.; Pogany, D.; Ostermaier, C. 2014-07-01 The high density of defect states at the dielectric/III-N interface in GaN based metal-insulator-semiconductor structures causes tremendous threshold voltage drifts, ΔVth, under forward gate bias conditions. A comprehensive study on different dielectric materials, as well as varying dielectric thickness tD and barrier thickness tB, is performed using capacitance-voltage analysis. It is revealed that the density of trapped electrons, ΔNit, scales with the dielectric capacitance under spill-over conditions, i.e., the accumulation of a second electron channel at the dielectric/AlGaN barrier interface. Hence, the density of trapped electrons is defined by the charging of the dielectric capacitance. The scaling behavior of ΔNit is explained universally by the density of accumulated electrons at the dielectric/III-N interface under spill-over conditions. We conclude that the overall density of interface defects is higher than what can be electrically measured, due to limits set by dielectric breakdown. These findings have a significant impact on the correct interpretation of threshold voltage drift data and are of relevance for the development of normally off and normally on III-N/GaN high electron mobility transistors with gate insulation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPCP8046D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPCP8046D">Investigations of Turbulent Transport Channels in Gyrokinetic Simulations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dimits, A. M.; Candy, J.; Guttenfelder, W.; Holland, C.; Howard, N.; Nevins, W. M.; Wang, E. 2014-10-01 Magnetic-field stochasticity arises due to microtearing perturbations, which can be driven linearly or nonlinearly (in cases where they are linearly stable), even at very modest values of the plasma beta. The resulting magnetic-flutter contribution may or may not be a significant component of the overall electron (particle and thermal) transport. Investigations of the effect of ExB flow shear on electron-drift magnetic-flutter diffusion coefficient Dedr (r ,v||) using perturbed magnetic fields from simulations, using the GYRO code, of ITG turbulence show a significant effect for electrons with parallel velocities v|| surprisingly far from the resonant velocity. We further examine changes in the radial dependence of this diffusion coefficient vs. v|| and which resonant magnetic-field perturbations are important to the values and radial structure of Dedr. The resulting electron transport fluxes are compared with the simulation results. Improvements over in treating the ambipolar field in the relationship between the magnetic (or drift) diffusion coefficients and the transport have been made in these comparisons. Prepared for US DOE by LLNL under Contract DE-AC52-07NA27344, by GA under Contract DE-FG03-95ER54309, and by PPPL under Contract DE-AC02-09CH11466. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599024-benchmark-studies-gyro-landau-fluid-code-gyro-kinetic-codes-kinetic-ballooning-modes','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599024-benchmark-studies-gyro-landau-fluid-code-gyro-kinetic-codes-kinetic-ballooning-modes">Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Tang, T. F.; Lawrence Livermore National Laboratory, Livermore, California 94550; Xu, X. Q. 2016-03-15 A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan basedmore » on “Cyclone base case parameter set.” We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........73S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........73S">Kilometer-Spaced GNSS Array for Ionospheric Irregularity Monitoring</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Su, Yang This dissertation presents automated, systematic data collection, processing, and analysis methods for studying the spatial-temporal properties of Global Navigation Satellite Systems (GNSS) scintillations produced by ionospheric irregularities at high latitudes using a closely spaced multi-receiver array deployed in the northern auroral zone. The main contributions include 1) automated scintillation monitoring, 2) estimation of drift and anisotropy of the irregularities, 3) error analysis of the drift estimates, and 4) multi-instrument study of the ionosphere. A radio wave propagating through the ionosphere, consisting of ionized plasma, may suffer from rapid signal amplitude and/or phase fluctuations known as scintillation. Caused by non-uniform structures in the ionosphere, intense scintillation can lead to GNSS navigation and high-frequency (HF) communication failures. With specialized GNSS receivers, scintillation can be studied to better understand the structure and dynamics of the ionospheric irregularities, which can be parameterized by altitude, drift motion, anisotropy of the shape, horizontal spatial extent and their time evolution. To study the structuring and motion of ionospheric irregularities at the sub-kilometer scale sizes that produce L-band scintillations, a closely-spaced GNSS array has been established in the auroral zone at Poker Flat Research Range, Alaska to investigate high latitude scintillation and irregularities. Routinely collecting low-rate scintillation statistics, the array database also provides 100 Hz power and phase data for each channel at L1/L2C frequency. In this work, a survey of seasonal and hourly dependence of L1 scintillation events over the course of a year is discussed. To efficiently and systematically study scintillation events, an automated low-rate scintillation detection routine is established and performed for each day by screening the phase scintillation index. The spaced-receiver technique is applied to cross-correlated phase and power measurements from GNSS receivers. Results of horizontal drift velocities and anisotropy ellipses derived from the parameters are shown for several detected events. Results show the possibility of routinely quantifying ionospheric irregularities by drifts and anisotropy. Error analysis on estimated properties is performed to further evaluate the estimation quality. Uncertainties are quantified by ensemble simulation of noise on the phase signals carried through to the observations of the spaced-receiver linear system. These covariances are then propagated through to uncertainties on drifts. A case study of a single scintillating satellite observed by the array is used to demonstrate the uncertainty estimation process. The distributed array is used in coordination with other measuring techniques such as incoherent scatter radar and optical all-sky imagers. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30-minute period are made and compared to a collocated incoherent scatter radar, and show good agreement in horizontal drift speed and direction during periods of scintillation for cases when the characteristic velocity is less than the drift velocity. The methods demonstrated are extensible to other zones and other GNSS arrays of varying size, number, ground distribution, and transmitter frequency. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ITNS...64.1611B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ITNS...64.1611B">New Position Algorithms for the 3-D CZT Drift Detector</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Budtz-Jørgensen, C.; Kuvvetli, I. 2017-06-01 The 3-D position sensitive CZT detector for high-energy astrophysics developed at DTU has been investigated with a digitizer readout system. The 3-D CZT detector is based on the CZT drift-strip detector principle and was fabricated using a REDLEN CZT crystal (20 mm × 20 mm × 5 mm). The detector contains 12 drift cells, each comprising one collecting anode strip with four drift strips, biased such that the electrons are focused and collected by the anode strips. Three-dimensional position determination is achieved using the anode strip signals, the drift-strip signals, and the signals from ten cathode strips. For the characterization work, we used a DAQ system with a 16 channels 250-MHz 14-b digitizer, SIS3316. It allowed us to analyze the pulse shapes of the signals from four detector cells at a time. The 3-D CZT setup was characterized with a finely collimated radioactive source of 137Cs at 662 keV. The analysis required development of novel position determination algorithms which are the subject of this paper. Using the digitizer readout, we demonstrate improved position determination compared to the previous read out system based on analog electronics. Position resolutions of 0.4-mm full width at half maximum (FWHM) in the x-, y-, and z-directions were achieved and the energy resolution was 7.2-keV FWHM at 662 keV. The timing information allows identification of multiple interaction events within one detector cell, e.g., Compton scattering followed by photoelectric absorption. These characteristics are very important for a high-energy spectral-imager suitable for use in advanced Compton telescopes, or as focal detector for new hard X-ray and soft γ-ray focusing telescopes or in polarimeter instrumentation. CZT detectors are attractive for these applications since they offer relatively high-quantum efficiency. From a technical point of view it is advantageous that their cooling requirements are modest. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/146006-two-different-types-enhanced-ion-acoustic-fluctuations-observed-upper-ionosphere','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/146006-two-different-types-enhanced-ion-acoustic-fluctuations-observed-upper-ionosphere"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Forme, F.R.E.; Fontaine, D.; Wahlund, J.E. UHF and VHF data for the EISCAT incoherent scatter radar facility in northern Scandinavia is presented. Electron and ion temperatures, electron density, and ion drift velocity were measured from heights of 280 to 1500 km. Enhanced ion acoustic fluctuations are more observable with VHF than UHF radar due to wavelength effects. The fluctuations are usually associated with a large flux of precipitating electrons with energies from 100 ev to 10 kev. The spatial extent of the turbulent regions are determined. 23 refs., 6 figs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..DNP.CG012G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..DNP.CG012G">Status of the DRIFT-II Directional Dark Matter Detector</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ghag, Chamkaur 2006-10-01 DRIFT is a directional dark matter detection programme that utilises the fact that as the Earth rotates and revolves around the Sun, an annual and diurnal signal modulation could be detected as a result of relative motion between the Earth and the non-rotating WIMP halo. This would provide very strong evidience of WIMPs since such a signal could not be mimicked by background sources. DRIFT II is an array of gas filled time projection chambers (TPCs) with Multi Wire Proportional Counter (MWPC) readout. Signals from different types of events differ greatly, between nuclear and electron recoils for example, due to the amount of ionisation initially produced and recombination times. This provides phenomenal discrimination capabilities. The first module of the DRIFT-II detector was successfully installed underground at Boulby Mine, N. Yorkshire early last year and has proven very stable, collecting high quality calibration and WIMP data. Since then a second module has been installed and is also currently operational. This presentation will describe the status of the detector and will focus on the determination of neutron efficiency and gamma rejection factors. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active">23</li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active">24</li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SoPh..292...94K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SoPh..292...94K">Oscillations in the 45 - 5000 MHz Radio Spectrum of the 18 April 2014 Flare</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Karlický, Marian; Rybák, Ján; Monstein, Christian 2017-07-01 Using a new type of oscillation map, made from the radio spectra by the wavelet technique, we study the 18 April 2014 M7.3 flare (SOL2014-04-18T13:03:00L245C017). We find a quasi-periodic character of this flare with periods in the range 65 - 115 seconds. At the very beginning of this flare, in connection with the drifting pulsation structure (plasmoid ejection), we find that the 65 - 115 s oscillation phase slowly drifts towards lower frequencies, which indicates an upward propagating wave initiated at the start of the magnetic reconnection. Many periods (1 - 200 seconds) are found in the drifting pulsation structure, which documents multi-scale and multi-periodic processes. On this drifting structure, fiber bursts with a characteristic period of about one second are superimposed, whose frequency drift is similar to that of the drifting 65 - 115 s oscillation phase. We also checked periods found in this flare by the EUV Imaging Spectrometer (EIS)/ Hinode and Interface Region Imaging Spectrograph (IRIS) observations. We recognize the type III bursts (electron beams) as proposed, but their time coincidence with the EIS and IRIS peaks is not very good. The reason probably is that the radio spectrum is a whole-disk record consisting of all bursts from any location, while the EIS and IRIS peaks are emitted only from locations of slits in the EIS and IRIS observations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1041095','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1041095">ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2017-06-30 17394 4 / 13 HALL EFFECT THRUSTERS Hall Effect Thrusters (HET): Traditionally Modeled in R-Z Named for Hall Current in θ Uses Quasi -1D Electron Fluid...HET): Traditionally Modeled in R-Z Named for Hall Current in θ Uses Quasi -1D Electron Fluid Solve Ohm’s Law→ No e−-momentum Zθ Unrolled to YZ...Current in θ Uses Quasi -1D Electron Fluid Solve Ohm’s Law→ No e−-momentum Zθ Unrolled to YZ Electron ExB Drift Unmagnetized Ions Results in Hall Current </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM41E..08R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM41E..08R">The role of localised Ultra-Low Frequency waves in energetic electron precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Rae, J.; Murphy, K. R.; Watt, C.; Mann, I. R.; Ozeke, L.; Halford, A. J.; Sibeck, D. G.; Clilverd, M. A.; Rodger, C. J.; Degeling, A. W.; Singer, H. J. 2016-12-01 Electromagnetic waves play pivotal roles in radiation belt dynamics through a variety of different means. Typically, Ultra-Low Frequency (ULF) waves have historically been invoked for radial diffusive transport leading to both acceleration and loss of outer radiation belt electrons. Very-Low Frequency (VLF) and Extremely-Low Frequency (ELF) waves are generally thought to provide a mechanism for localized acceleration and loss through precipitation into the ionosphere. In this study we present a new mechanism for electron loss through precipitation into the ionosphere due to direct modulation of the loss cone via localized compressional ULF waves. Observational evidence is presented demonstrating that modulation of the equatorial loss cone can occur via localized compressional wave activity. We then perform statistical computations of the probability distribution to determine how likely a given magnetic perturbation would produce a given percentage change in the bounce loss-cone (BLC). We discuss the ramifications of the action of coherent, localized compressional ULF waves on drifting electron populations; their precipitation response can be a complex interplay between electron energy, the shape of the phase space density profile at pitch angles close to the loss cone, ionospheric decay timescales, and the time-dependence of the electron source. We present a case study of compressional wave activity in tandem with riometer and balloon-borne electron precipitation across keV-MeV energies to demonstrate that the experimental measurements can be explained by our new enhanced loss cone mechanism. We determine that the two pivotal components not usually considered are localized ULF wave fields and ionospheric decay timescales. We conclude that ULF wave modulation of the loss cone is a viable candidate for direct precipitation of radiation belt electrons without any additional requirement for gyroresonant wave-particle interaction. Additional mechanisms would be complementary and additive in providing means to precipitate electrons from the radiation belts during storm-times. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750000095','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750000095">Simple and effective method to lock buoy position to ocean currents</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Vachon, W. A.; Dahlen, J. M. 1975-01-01 Window-shade drogue, used with drifting buoys to keep them moving with current at speed as close to that of current as possible, has drag coefficient of 1.93 compared to maximum of 1.52 for previous drogues. It is remarkably simple to construct, use, and store. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989NIMPA.283..477B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989NIMPA.283..477B">Development of the ZEUS central tracking detector</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Brooks, C. B.; Bullock, F. W.; Cashmore, R. J.; Devenish, R. C.; Foster, B.; Fraser, T. J.; Gibson, M. D.; Gilmore, R. S.; Gingrich, D.; Harnew, N.; Hart, J. C.; Heath, G. P.; Hiddleston, J.; Holmes, A. R.; Jamdagni, A. K.; Jones, T. W.; Llewellyn, T. J.; Long, K. R.; Lush, G. J.; Malos, J.; Martin, N. C.; McArthur, I.; McCubbin, N. A.; McQuillan, D.; Miller, D. B.; Mobayyen, M. M.; Morgado, C.; Nash, J.; Nixon, G.; Parham, A. G.; Payne, B. T.; Roberts, J. H. C.; Salmon, G.; Saxon, D. H.; Sephton, A. J.; Shaw, D.; Shaw, T. B.; Shield, P. D.; Shulman, J.; Silvester, I.; Smith, S.; Strachan, D. E.; Tapper, R. J.; Tkaczyk, S. M.; Toudup, L. W.; Wallis, E. W.; Wastie, R.; Wells, J.; White, D. J.; Wilson, F. F.; Yeo, K. L.; ZEUS-UK Collaboration 1989-11-01 The design concept and development of the ZEUS central tracking detector is described. This is a cylindrical drift chamber designed for track reconstruction, electron identification and event triggering in a high-crossing-rate, high-magnetic-field environment. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27018779','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27018779">Non-rigid alignment in electron tomography in materials science.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Printemps, Tony; Bernier, Nicolas; Bleuet, Pierre; Mula, Guido; Hervé, Lionel 2016-09-01 Electron tomography is a key technique that enables the visualization of an object in three dimensions with a resolution of about a nanometre. High-quality 3D reconstruction is possible thanks to the latest compressed sensing algorithms and/or better alignment and preprocessing of the 2D projections. Rigid alignment of 2D projections is routine in electron tomography. However, it cannot correct misalignments induced by (i) deformations of the sample due to radiation damage or (ii) drifting of the sample during the acquisition of an image in scanning transmission electron microscope mode. In both cases, those misalignments can give rise to artefacts in the reconstruction. We propose a simple-to-implement non-rigid alignment technique to correct those artefacts. This technique is particularly suited for needle-shaped samples in materials science. It is initiated by a rigid alignment of the projections and it is then followed by several rigid alignments of different parts of the projections. Piecewise linear deformations are applied to each projection to force them to simultaneously satisfy the rigid alignments of the different parts. The efficiency of this technique is demonstrated on three samples, an intermetallic sample with deformation misalignments due to a high electron dose typical to spectroscopic electron tomography, a porous silicon sample with an extremely thin end particularly sensitive to electron beam and another porous silicon sample that was drifting during image acquisitions. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014HyInt.225..193M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014HyInt.225..193M">The MTV experiment: a test of time reversal symmetry using polarized 8Li</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Murata, J.; Baba, H.; Behr, J. A.; Hirayama, Y.; Iguri, T.; Ikeda, M.; Kato, T.; Kawamura, H.; Kishi, R.; Levy, C. D. P.; Nakaya, Y.; Ninomiya, K.; Ogawa, N.; Onishi, J.; Openshaw, R.; Pearson, M.; Seitaibashi, E.; Tanaka, S.; Tanuma, R.; Totsuka, Y.; Toyoda, T. 2014-01-01 The MTV ( Mott Polarimetry for T- Violation Experiment) experiment at TRIUMF-ISAC ( Isotope Separator and ACcelerator), which aims to achieve the highest precision test of time reversal symmetry in polarized nuclear beta decay by measuring a triple correlation ( R-correlation), is motivated by the search for a new physics beyond the Standard Model. In this experiment, the existence of non-zero transverse electron polarization is examined utilizing the analyzing power of Mott scattering from a thin metal foil. Backward scattering electron tracks are measured using a multi-wire drift chamber for the first time. The MTV experiment was commissioned at ISAC in 2009 using an 80 % polarized 8Li beam at 107 pps, resulting in 0.1 % statistical precision on the R-parameter in the first physics run performed in 2010. Next generation cylindrical drift chamber (CDC) is now being installed for the future run. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1953i0084K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1953i0084K">Technique for measurement of energy loss of proton in target medium</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Khadke, U. V. 2018-05-01 Energy loss (EL) of charged particles in target medium needs special attention, when measurements are required to be done repeatedly over periods of couple of days. It is imperative to ensure that the measurements are not affected by the long term drifts of the accelerator beam energy and the associated electronic modules. For one such situation in measurement of EL of proton beam in thick target, we optimised and standardized the technique of measuring most probable energy loss of 24.774 MeV proton in aluminium target of thickness 330 mg/cm2. The paper described the method that we developed to ensure that our EL measurements were free from effects of drifts due to any associated electronic modules. The details of the energy spectrometer, basic principle and technique for energy loss measurements in target medium are described in this paper. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SSSci..65...15M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SSSci..65...15M">BiOBr microspheres for photocatalytic degradation of an anionic dye</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mera, Adriana C.; Váldes, Héctor; Jamett, Fabiola J.; Meléndrez, M. F. 2017-03-01 BiOBr microspheres were obtained using a solvothermal synthesis route in the presence of ethylene glycol and KBr at 145 °C, for 18 h. BiOBr microspheres were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption-desorption isotherms analysis, diffuse reflectance spectroscopy (DRS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Additionally, the theoretical and experimental isoelectric points (IEP) of BiOBr nanostructured microspheres were determined, and pH's influence on the degradation of an anionic dye (methyl orange) under simulated solar radiation was analyzed. Results show that 97% of methyl orange is removed at pH 2 after 60 min of photocatalytic reaction. Finally, DRIFTS studies permit the proposal of a surface reaction mechanism of the photocatalytic oxidation of MO using BiOBr microspheres. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25e3509W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25e3509W">Investigation of surface boundary conditions for continuum modeling of RF plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wilson, A.; Shotorban, B. 2018-05-01 This work was motivated by a lacking general consensus in the exact form of the boundary conditions (BCs) required on the solid surfaces for the continuum modeling of Radiofrequency (RF) plasmas. Various kinds of number and energy density BCs on solid surfaces were surveyed, and how they interacted with the electric potential BC to affect the plasma was examined in two fundamental RF plasma reactor configurations. A second-order local mean energy approximation with equations governing the electron and ion number densities and the electron energy density was used to model the plasmas. Zero densities and various combinations of drift, diffusion, and thermal fluxes were considered to set up BCs. It was shown that the choice of BC can have a significant impact on the sheath and bulk plasma. The thermal and diffusion fluxes to the surface were found to be important. A pure drift BC for dielectric walls failed to produce a sheath. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060043604&hterms=ionosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dionosphere','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060043604&hterms=ionosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dionosphere">Assimilative modeling of low latitude ionosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Pi, Xiaoqing; Wang, Chunining; Hajj, George A.; Rosen, I. Gary; Wilson, Brian D.; Mannucci, Anthony J. 2004-01-01 In this paper we present an observation system simulation experiment for modeling low-latitude ionosphere using a 3-dimensional (3-D) global assimilative ionospheric model (GAIM). The experiment is conducted to test the effectiveness of GAIM with a 4-D variational approach (4DVAR) in estimation of the ExB drift and thermospheric wind in the magnetic meridional planes simultaneously for all longitude or local time sectors. The operational Global Positioning System (GPS) satellites and the ground-based global GPS receiver network of the International GPS Service are used in the experiment as the data assimilation source. 'The optimization of the ionospheric state (electron density) modeling is performed through a nonlinear least-squares minimization process that adjusts the dynamical forces to reduce the difference between the modeled and observed slant total electron content in the entire modeled region. The present experiment for multiple force estimations reinforces our previous assessment made through single driver estimations conducted for the ExB drift only. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JSP...171..696B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JSP...171..696B">Quantum Transmission Conditions for Diffusive Transport in Graphene with Steep Potentials</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Barletti, Luigi; Negulescu, Claudia 2018-05-01 We present a formal derivation of a drift-diffusion model for stationary electron transport in graphene, in presence of sharp potential profiles, such as barriers and steps. Assuming the electric potential to have steep variations within a strip of vanishing width on a macroscopic scale, such strip is viewed as a quantum interface that couples the classical regions at its left and right sides. In the two classical regions, where the potential is assumed to be smooth, electron and hole transport is described in terms of semiclassical kinetic equations. The diffusive limit of the kinetic model is derived by means of a Hilbert expansion and a boundary layer analysis, and consists of drift-diffusion equations in the classical regions, coupled by quantum diffusive transmission conditions through the interface. The boundary layer analysis leads to the discussion of a four-fold Milne (half-space, half-range) transport problem. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1376546-energy-reconstruction-type-segmented-inverted-coaxial-point-contact-hpge-detector','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1376546-energy-reconstruction-type-segmented-inverted-coaxial-point-contact-hpge-detector">Energy reconstruction of an n-type segmented inverted coaxial point-contact HPGe detector</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Salathe, M.; Cooper, R. J.; Crawford, H. L.; ... 2017-06-27 We have characterized, for the rst time, an n-type segmented Inverted Coaxial Point-Contact detector. This novel detector technology relys on a large variation in drift time of the majority charge carriers, as well as image and net charges observed on the segments, to achieve a potential -ray interaction position resolution of better than 1 mm. However, the intrinsic energy resolution in such a detector is poor (more than 20 keV at 1332 keV) because of charge (electron) trapping e ects. We propose an algorithm that enables restoration of the resolution to a value of 3.44 0.03 keV at 1332 keVmore » for events with a single interaction. The algorithm is based on a measurement of the azimuthal angle and the electron drift time of a given event; the energy of the event is corrected as a function of these two values.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900047686&hterms=waves+electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dwaves%2Belectromagnetic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900047686&hterms=waves+electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dwaves%2Belectromagnetic">Amplification of a high-frequency electromagnetic wave by a relativistic plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Yoon, Peter H. 1990-01-01 The amplification of a high-frequency transverse electromagnetic wave by a relativistic plasma component, via the synchrotron maser process, is studied. The background plasma that supports the transverse wave is considered to be cold, and the energetic component whose density is much smaller than that of the background component has a loss-cone feature in the perpendicular momentum space and a finite field-aligned drift speed. The ratio of the background plasma frequency squared to the electron gyrofrequency squared is taken to be sufficiently larger than unity. Such a parameter regime is relevant to many space and astrophysical situations. A detailed study of the amplification process is carried out over a wide range of physical parameters including the loss-cone index, the ratio of the electron mass energy to the temperature of the energetic component, the field-aligned drift speed, the normalized density, and the wave propagation angle. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1361823-understanding-impact-insulating-conducting-endplate-boundary-conditions-turbulence-csdx-through-nonlocal-simulations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1361823-understanding-impact-insulating-conducting-endplate-boundary-conditions-turbulence-csdx-through-nonlocal-simulations">Understanding the impact of insulating and conducting endplate boundary conditions on turbulence in CSDX through nonlocal simulations</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Vaezi, P.; Holland, C.; Thakur, S. C.; ... 2017-04-01 The Controlled Shear Decorrelation Experiment (CSDX) linear plasma device provides a unique platform for investigating the underlying physics of self-regulating drift-wave turbulence/zonal flow dynamics. A minimal model of 3D drift-reduced nonlocal cold ion fluid equations which evolves density, vorticity, and electron temperature fluctuations, with proper sheath boundary conditions, is used to simulate dynamics of the turbulence in CSDX and its response to changes in parallel boundary conditions. These simulations are then carried out using the BOUndary Turbulence (BOUT++) framework and use equilibrium electron density and temperature profiles taken from experimental measurements. The results show that density gradient-driven drift-waves are themore » dominant instability in CSDX. However, the choice of insulating or conducting endplate boundary conditions affects the linear growth rates and energy balance of the system due to the absence or addition of Kelvin-Helmholtz modes generated by the sheath-driven equilibrium E × B shear and sheath-driven temperature gradient instability. Moreover, nonlinear simulation results show that the boundary conditions impact the turbulence structure and zonal flow formation, resulting in less broadband (more quasi-coherent) turbulence and weaker zonal flow in conducting boundary condition case. These results are qualitatively consistent with earlier experimental observations.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/840018','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/840018">Doubling The Intensity Of An ERL Based Light Source</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Andrew Hutton 2005-05-01 A light source based on an Energy Recovered Linac (ERL) [1] consists of a superconducting linac and a transfer line that includes wigglers and undulators to produce the synchrotron light. The transfer line brings the electron bunches back to the beginning of the linac so that their energy can be recovered when they traverse the linac a second time, {lambda}/2 out of RF phase. There is another interesting condition when the length of the transfer line is (n {+-} 1/4) {lambda}. In this case, the electrons drift through on the zero RF crossing, and make a further pass around themore » transfer line, effectively doubling the circulating current in the wigglers and undulators. On the third pass through the linac, they will be decelerated and their energy recovered. The longitudinal focusing at the zero crossing is a problem, but it can be canceled if the drifting beam sees a positive energy gradient for the first half of the linac and a negative gradient for the second half (or vice versa). This paper presents a proposal to use a double chicane at the center of the linac to provide this focusing inversion for the drifting beam while leaving the accelerating and decelerating beams on crest. [1] G. R. Neil, et al, Phys. Rev. Let. 84, 662 2000« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..APR.E9005Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..APR.E9005Y">An FPGA-based data acquisition system for directional dark matter detection</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yang, Chen; Nicoloff, Catherine; Sanaullah, Ahmed; Sridhar, Arvind; Herbordt, Martin; Battat, James; Battat Lab at Wellesley College Team; CAAD Lab at Boston University Team 2017-01-01 Directional dark matter detection is a powerful tool in the search for dark matter. Low-pressure gas TPCs are commonly used for directional detection, and dark-matter-induced recoils are mm long. These tracks can be reconstructed by micropatterned readouts. Because large detector volumes are needed, a cost-effective data acquisition system capable of scaling to large channel counts (105 or 106) is required. The Directional Recoil Identification From Tracks (DRIFT) collaboration has pioneered the use of TPCs for directional detection. We employ a negative ion gas with drift speed comparable to the electron drift speed in liquid argon (LAr). We aim to use electronics developed for million-channel readouts in large LAr neutrino detectors. We have built a prototype Micromegas-based directional detector with 103 channels. A FPGA-based back-end system (BE) receives a 12 Gbps data stream from eight ASIC-based front-end boards (FE), each with 128 detector channels. The BE buffers 3 μs of pretrigger data for all channels in DRAM, and streams triggered data to a host PC. We will describe the system architecture and present preliminary measurements from the DAQ. We acknowledge the support of the Research Corporation for Science Advancement, the NSF and the Massachusetts Space Grant Consortium. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.474.3090O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.474.3090O">Diffusion-plus-drift models for the mass leakage from centrifugal magnetospheres of magnetic hot-stars</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Owocki, Stanley P.; Cranmer, Steven R. 2018-03-01 In the subset of luminous, early-type stars with strong, large-scale magnetic fields and moderate to rapid rotation, material from the star's radiatively driven stellar wind outflow becomes trapped by closed magnetic loops, forming a centrifugally supported, corotating magnetosphere. We present here a semi-analytic analysis of how this quasi-steady accumulation of wind mass can be balanced by losses associated with a combination of an outward, centrifugally driven drift in the region beyond the Kepler co-rotation radius, and an inward/outward diffusion near this radius. We thereby derive scaling relations for the equilibrium spatial distribution of mass, and the associated emission measure for observational diagnostics like Balmer line emission. We discuss the potential application of these relations for interpreting surveys of the emission line diagnostics for OB stars with centrifugally supported magnetospheres. For a specific model of turbulent field-line-wandering rooted in surface motions associated with the iron opacity bump, we estimate values for the associated diffusion and drift coefficients. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23i3301K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23i3301K">Smith-Purcell terahertz radiation from laser modulated electron beam over a metallic grating</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kumar, Pawan; Bhasin, Lalita; Tripathi, V. K.; Kumar, Ashok; Kumar, Manoj 2016-09-01 We propose a novel scheme of terahertz (THz) radiation generation from the beat frequency modulation of an electron beam by two co-propagating lasers and the generation of terahertz radiation by the modulated beam passing over a periodic metallic grating. The lasers cause velocity modulation of the beam by exerting a longitudinal ponderomotive force on it. In the drift space between the modulator and metallic grating, the velocity modulation translates into density and current modulation. The modulated beam, propagating over the grating of specific wave number, induces space periodic image current in the conductor that emits beat frequency Smith-Purcell radiation. With 1 μm, 4 × 1016 W/cm2 lasers, beam current modulation of the order of 50% can be achieved at optimum lengths of the modulator and drift space. Employing 10 mA, 0.5 MeV short-period electron beam, propagating at a height of 50 μ m above the grating of period 150 μm, one may obtain THz radiated power of the order of 6 mW at 10 THz. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009SPIE.7312E..0SO','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009SPIE.7312E..0SO">Fast detection of toxic industrial compounds by laser ion mobility spectrometry</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Oberhuettinger, Carola; Langmeier, Andreas; Oberpriller, Helmut; Kessler, Matthias; Goebel, Johann; Mueller, Gerhard 2009-05-01 Trace detection of toxic industrial compounds has been investigated with the help of a laser ion mobility spectrometer (LIMS). The LIMS was equipped with a tuneable UV laser source for enabling two-photon ionization of the analyte gases and an ion drift tube for the measurement of the ion mobility. Different aromatic and aliphatic hydrocarbons as well as amines were investigated. We find that the first class of molecules can be well ionized due to the delocalization of their valence electron shells and the second due to the presence of non-bonding electrons in lone-pair orbitals. Selectivity of detection is attained on the basis of molecule-specific photo-ionization and drift time spectra. Ion currents were found to scale linearly with the substance concentration over several orders of magnitude down to the detection limits in the ppt range. As besides toxic industrial compounds, similar electron configurations also occur in illicit drugs, toxins and pharmaceutical substances, LIMS can be applied in a variety of fields ranging from environmental analysis, air pollution monitoring, drug detection and chemical process monitoring. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active">24</li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active">25</li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ITNS...62.1785K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ITNS...62.1785K">Quantification of the Conditioning Phase in Cooled Pixelated TlBr Detectors</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Koehler, Will; He, Zhong; O'Neal, Sean; Yang, Hao; Kim, Hadong; Cirignano, Leonard; Shah, Kanai 2015-08-01 Thallium-bromide (TlBr) is currently under investigation as an alternative room-temperature semiconductor gamma-ray spectrometer due to its favorable material properties (large bandgap, high atomic numbers, and high density). Previous work has shown that 5 mm thick pixelated TlBr detectors can achieve sub-1% FWHM energy resolution at 662 keV for single-pixel events. These results are limited to - 20° C operation where detector performance is stable. During the first one to five days of applied bias at - 20° C, many TlBr detectors undergo a conditioning phase, where the energy resolution improves and the depth-dependent electron drift velocity stabilizes. In this work, the spectroscopic performance, drift velocity, and freed electron concentrations of multiple 5 mm thick pixelated TlBr detectors are monitored throughout the conditioning phase. Additionally, conditioning is performed twice on the same detector at different times to show that improvement mechanisms relax when the detector is stored without bias. We conclude that the improved spectroscopy results from internal electric field stabilization and uniformity caused by fewer trapped electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730039930&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DButterfly','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730039930&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DButterfly">Electron pitch angle distributions throughout the magnetosphere as observed on Ogo 5.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> West, H. I., Jr.; Buck, R. M.; Walton, J. R. 1973-01-01 A survey of the equatorial pitch angle distributions of energetic electrons is provided for all local times out to radial distances of 20 earth radii on the night side of the earth and to the magnetopause on the day side of the earth. In much of the inner magnetosphere and in the outer magnetosphere on the day side of the earth, the normal loss cone distribution prevails. The effects of drift shell splitting - i.e., the appearance of pitch angle distributions with minimums at 90 deg, called butterfly distributions - become apparent in the early afternoon magnetosphere at extended distances, and the distribution is observed in to 5.5 earth radii in the nighttime magnetosphere. Inside about 9 earth radii the pitch angle effects are quite energy-dependent. Beyond about 9 earth radii in the premidnight magnetosphere during quiet times the butterfly distribution is often observed. It is shown that these electrons cannot survive a drift to dawn without being considerably modified. The role of substorm activity in modifying these distributions is identified. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..DPPGP8030C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..DPPGP8030C">Heating and background plasma modification associated with large amplitude kinetic Alfv'en wave launch in LAPD</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Carter, T. A.; Auerbach, D. W.; Brugman, B. T. 2007-11-01 Large amplitude kinetic Alfv'en waves (δB/B ˜1% > k/k) are generated in the Large Plasma Device (LAPD) at UCLA using loop antennas. Substantial electron heating is observed, localized to the wave current channels. The Poynting flux associated with the Alfv'en waves is substantial and the observed heating may be at least in part due to collisional and Landau damping of these waves. However, heating by antenna near inductive electric fields may also be responsible for the observations. A discussion of both possibilities will be presented, including measurements of near fields of the antenna. The heating structures the background plasma and results in the excitation of drift-Alfv'en waves. These drift waves then interact with the incident Alfv'en wave, causing sideband generation which results in a nearly broadband state at high wave power. This process may represent an alternate mechanism by which unidirectional kinetic Alfv'en waves can nonlinearly generate a turbulent spectrum. In addition to electron heating, evidence for background density modification and electron acceleration is observed and will be presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23g2113C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23g2113C">Flux-driven algebraic damping of m = 1 diocotron mode</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chim, Chi Yung; O'Neil, Thomas M. 2016-07-01 Recent experiments with pure electron plasmas in a Malmberg-Penning trap have observed the algebraic damping of m = 1 diocotron modes. Transport due to small field asymmetries produces a low density halo of electrons moving radially outward from the plasma core, and the mode damping begins when the halo reaches the resonant radius r = Rw at the wall of the trap. The damping rate is proportional to the flux of halo particles through the resonant layer. The damping is related to, but distinct from, spatial Landau damping, in which a linear wave-particle resonance produces exponential damping. This paper explains with analytic theory the new algebraic damping due to particle transport by both mobility and diffusion. As electrons are swept around the "cat's eye" orbits of the resonant wave-particle interaction, they form a dipole (m = 1) density distribution. From this distribution, the electric field component perpendicular to the core displacement produces E × B-drift of the core back to the axis, that is, damps the m = 1 mode. The parallel component produces drift in the azimuthal direction, that is, causes a shift in the mode frequency. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPU10036M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPU10036M">Analytical and numerical treatment of drift-tearing modes in plasma slab</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mirnov, V. V.; Hegna, C. C.; Sovinec, C. R.; Howell, E. C. 2016-10-01 Two-fluid corrections to linear tearing modes includes 1) diamagnetic drifts that reduce the growth rate and 2) electron and ion decoupling on short scales that can lead to fast reconnection. We have recently developed an analytical model that includes effects 1) and 2) and important contribution from finite electron parallel thermal conduction. Both the tendencies 1) and 2) are confirmed by an approximate analytic dispersion relation that is derived using a perturbative approach of small ion-sound gyroradius ρs. This approach is only valid at the beginning of the transition from the collisional to semi-collisional regimes. Further analytical and numerical work is performed to cover the full interval of ρs connecting these two limiting cases. Growth rates are computed from analytic theory with a shooting method. They match the resistive MHD regime with the dispersion relations known at asymptotically large ion-sound gyroradius. A comparison between this analytical treatment and linear numerical simulations using the NIMROD code with cold ions and hot electrons in plasma slab is reported. The material is based on work supported by the U.S. DOE and NSF. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22402680-incorporating-photon-recycling-analytical-drift-diffusion-model-high-efficiency-solar-cells','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22402680-incorporating-photon-recycling-analytical-drift-diffusion-model-high-efficiency-solar-cells">Incorporating photon recycling into the analytical drift-diffusion model of high efficiency solar cells</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Lumb, Matthew P.; Naval Research Laboratory, Washington, DC 20375; Steiner, Myles A. The analytical drift-diffusion formalism is able to accurately simulate a wide range of solar cell architectures and was recently extended to include those with back surface reflectors. However, as solar cells approach the limits of material quality, photon recycling effects become increasingly important in predicting the behavior of these cells. In particular, the minority carrier diffusion length is significantly affected by the photon recycling, with consequences for the solar cell performance. In this paper, we outline an approach to account for photon recycling in the analytical Hovel model and compare analytical model predictions to GaAs-based experimental devices operating close tomore » the fundamental efficiency limit.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..91c3113B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..91c3113B">Drift wave stabilized by an additional streaming ion or plasma population</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bashir, M. F.; Vranjes, J. 2015-03-01 It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vp h-vf 0) exp[-(vph-vf 0) 2] , where vf 0 is the flow speed and vp h is the phase speed parallel to the magnetic field vector. The damping is strong and it is mainly due to this ion exponential term, and this remains so for vf 0<vp h . </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25871230','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25871230">Drift wave stabilized by an additional streaming ion or plasma population.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Bashir, M F; Vranjes, J 2015-03-01 It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vph-vf0)exp[-(vph-vf0)2], where vf0 is the flow speed and vph is the phase speed parallel to the magnetic field vector. The damping is strong and it is mainly due to this ion exponential term, and this remains so for vf0<vph. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920063450&hterms=oxide+heterojunction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Doxide%2Bheterojunction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920063450&hterms=oxide+heterojunction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Doxide%2Bheterojunction">Modeling of planar varactor frequency multiplier devices with blocking barriers</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lieneweg, Udo; Tolmunen, T. J.; Frerking, Margaret A.; Maserjian, Joseph 1992-01-01 Models for optimization of planar frequency triplers with symmetrical C-V curves are presented. Role and limitation of various blocking barriers (oxide, Mott, heterojunction) are discussed. Devices with undoped drift regions (BIN) have moderate efficiency but a broad range of power operation, whereas devices with doped drift regions (BNN) have high efficiency in a narrow power window. In particular, an upper power limit of the BNN is caused by electron velocity saturation. Implementations in SiO2/Si and AlAs/GaAs and means for increasing the power of BNN structures are considered. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992ITMTT..40..839L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992ITMTT..40..839L">Modeling of planar varactor frequency multiplier devices with blocking barriers</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lieneweg, Udo; Tolmunen, T. J.; Frerking, Margaret A.; Maserjian, Joseph 1992-05-01 Models for optimization of planar frequency triplers with symmetrical C-V curves are presented. Role and limitation of various blocking barriers (oxide, Mott, heterojunction) are discussed. Devices with undoped drift regions (BIN) have moderate efficiency but a broad range of power operation, whereas devices with doped drift regions (BNN) have high efficiency in a narrow power window. In particular, an upper power limit of the BNN is caused by electron velocity saturation. Implementations in SiO2/Si and AlAs/GaAs and means for increasing the power of BNN structures are considered. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22469688-dynamic-characteristics-sic-drift-step-recovery-diodes','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22469688-dynamic-characteristics-sic-drift-step-recovery-diodes">Dynamic characteristics of 4H-SiC drift step recovery diodes</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Ivanov, P. A., E-mail: Pavel.Ivanov@mail.ioffe.ru; Kon’kov, O. I.; Samsonova, T. P. The dynamic characteristics of 4H-SiC p{sup +}–p–n{sub 0}–n{sup +} diodes are experimentally studied in the pulsed modes characteristic of the operation of drift step recovery diodes (DSRD-mode). The effect of the subnanosecond termination of the reverse current maintained by electron-hole plasma preliminarily pumped by a forward current pulse is analyzed in detail. The influence exerted on the DSRD effect by the amplitude of reverse-voltage pulses, the amplitude and duration of forward-current pulses, and the time delay between the forward and reverse pulses is demonstrated and accounted for. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994AIPC..301.1283K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994AIPC..301.1283K">Development of 4.5 kW SPT T-160 for Joint Tests with NPP TOPAZ-2</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Koroteev, Anatoly; Petrosov, Valery A.; Vasin, Anatoly L.; Baranov, Vladimir L.; Rebrov, Serdei G.; Wetch, Joseph R.; Wong, See-Pok 1994-07-01 The electric thruster T-160 is related to a low thrust rocket engines group which can be used on spacecrafts for their orbit correction and parameters change. T-160 flight tests are supposed to be conducted together with the TOPAZ-2 Nuclear Power Plant (NPP) as a part of the NEPSTP program. The thruster T-160 is a Hall-type plasma accelerator with the closed electron drift. Plasma is accelerated in crossed magnetic and electric fields in an accelerating channel made of insulating material. Gaseous xenon is used as a propellant for the thruster, electric power supply of 4-4.5 kW is required for its operation. The cathode-neutralizer emission element is made of porous tungsten saturated with barium salts. The thruster T-160 is equipped with a flow control unit ensuring propellant coming to the cathode and gas distributing anode, and a power processing unit and can be delivered with a propellant storage and supply system, thus forming a complete propulsion system set. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPA....7a5008L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPA....7a5008L">Magnetic field deformation due to electron drift in a Hall thruster</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Liang, Han; Yongjie, Ding; Xu, Zhang; Liqiu, Wei; Daren, Yu 2017-01-01 The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC) method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM). The results show that the direct Hall current decreases the magnetic field strength in the acceleration region and also changes the shape of the magnetic field. The maximum reduction in radial magnetic field strength in the exit plane is 10.8 G for an anode flow rate of 15 mg/s and the maximum angle change of the magnetic field line is close to 3° in the acceleration region. The alternating Hall current induces an oscillating magnetic field in the whole discharge channel. The actual magnetic deformation is shown to contain these two parts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5272193','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/5272193">Device and method for electron beam heating of a high density plasma</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Thode, L.E. A device and method for relativistic electron beam heating of a high density plasma in a small localized region are described. A relativistic electron beam generator produces a high voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high density target plasma which typically comprises DT, DD, hydrogen boron or similar thermonuclear gas at a density of 10/sup 17/ to 10/sup 20/. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29426158','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29426158">First attempts to obtain a reference drift curve for traditional olive grove's plantations following ISO 22866.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Gil, Emilio; Llorens, Jordi; Gallart, Montserrat; Gil-Ribes, Jesús A; Miranda-Fuentes, Antonio 2018-06-15 The current standard for the field measurements of spray drift (ISO 22866) is the only official standard for drift measurements in field conditions for all type of crops, including bushes and trees. A series of field trials following all the requirements established in the standard were arranged in a traditional olive grove in Córdoba (south of Spain). The aims of the study were to evaluate the applicability of the current standard procedure to the particular conditions of traditional olive trees plantations, to evaluate the critical requirements for performing the tests and to obtain a specific drift curve for such as important and specific crop as olive trees in traditional plantations, considering the enormous area covered by this type of crop all around the world. Results showed that the field trials incur a very complex process due to the particular conditions of the crop and the very precise environmental requirements. Furthermore, the trials offered a very low level of repeatability as the drift values varied significantly from one spray application to the next, with the obtained results being closely related to the wind speed, even when considering the standard minimum value of 1 m·s -1 . The collector's placement with respect to the position of the isolated trees was determined as being critical since this substantially modifies the ground deposit in the first 5 m. Even though, a new drift curve for olive trees in traditional plantation has been defined, giving an interesting tool for regulatory aspects. Conclusions indicated that a deep review of the official standard is needed to allow its application to the most relevant orchard/fruit crops. Copyright © 2018 Elsevier B.V. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://eric.ed.gov/?q=presentation+AND+Electronics&pg=6&id=EJ825946','ERIC'); return false;" href="https://eric.ed.gov/?q=presentation+AND+Electronics&pg=6&id=EJ825946">The Relation between Relaxation Time, Mean Free Path, Collision Time and Drift Velocity--Pitfalls and a Proposal for an Approach Illustrating the Essentials</a> <a target="_blank" rel="noopener noreferrer" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a> Jakoby, Bernhard 2009-01-01 The collision model is frequently introduced to describe electronic conductivity in solids. Depending on the chosen approach, the introduction of the collision time can lead to erroneous results for the average velocity of the electrons, which enters the expression for the electrical conductivity. In other textbooks, correct results are obtained… </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.......144C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.......144C">Collisional relaxation of an isotopic, strongly magnetized pure ion plasma and topics in resonant wave-particle interaction of plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chim, Chi Yung First in Chapter 2, we discuss the collisional relaxation of a strongly magnetized pure ion plasma that is composed of two species with slightly different masses, but both with singly-ionized atoms. In a limit of high cyclotron frequencies O j, the total cyclotron action Ij for the two species are adiabatic invariants. In a few collisions, maximizing entropy yields a modified Gibbs distribution of the form exp[-H/T ∥-alpha1 I 1-alpha2I2]. Here, H is the total Hamiltonian and alphaj's are related to parallel and perpendicular temperatures through T ⊥j=(1/T∥ +alphaj/Oj) -1. On a longer timescale, the two species share action so that alpha 1 and alpha2 relax to a common value alpha. On an even longer timescale, the total action ceases to be a constant of the motion and alpha relaxes to zero. Next, weak transport produces a low density halo of electrons moving radially outward from the pure electron plasma core, and the m = 1 mode begins to damp algebraically when the halo reaches the wall. The damping rate is proportional to the particle flux through the resonant layer at the wall. Chapter 3 explains analytically the new algebraic damping due to both mobility and diffusion transport. Electrons swept around the resonant "cat's eye" orbits form a dipole (m = 1) density distribution, setting up a field that produces ExB-drift of the core back to the axis, that is, damps the mode. Finally, Chapter 4 provides a simple mechanistic interpretation of the resonant wave-particle interaction of Landau. For the simple case of a Vlasov plasma oscillation, the non-resonant electrons are driven resonantly by the bare electric field from the resonant electrons, and this complex driver field is of a phase to reduce the oscillation amplitude. The wave-particle resonant interaction also occurs in 2D ExB-drift waves, such as a diocotron wave. In this case, the bare electric field from the resonant electrons causes ExB-drift motion back in the core plasma, thus damping the wave. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880026269&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880026269&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam">Electron/ion whistler instabilities and magnetic noise bursts</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Akimoto, K.; Gary, S. Peter; Omidi, N. 1987-01-01 Two whistler instabilities are investigated by means of the linear Vlasov dispersion equation. They are called the electron/ion parallel and oblique whistler instabilities, and are driven by electron/ion relative drifts along the magnetic field. It is demonstrated that the enhanced fluctuations from these instabilities can explain several properties of magnetic noise bursts in and near the plasma sheet in the presence of ion beams and/or field-aligned currents. At sufficiently high plasma beta, these instabilities may affect the current system in the magnetotail. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866210','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866210">Short rise time intense electron beam generator</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Olson, Craig L. 1987-01-01 A generator for producing an intense relativistic electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6115260','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6115260">Short rise time intense electron beam generator</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/doepatents">DOEpatents</a> Olson, C.L. 1984-03-16 A generator for producing an intense relativisitc electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active">25</li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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Sample records for closed electron drift