Multipactor Discharge in High Power Microwave Systems: Analyzing Effects and Mitigation through Simulation in ICEPIC

DTIC Science & Technology

2013-03-01

weapons, 2012. Private Communication. 22. A. Valfells, H.P. Verboncoeur, and Y.Y. Lau. Space - charge effects on multipactor dielectric . Plasma Science...when space charge effects are omitted modeled particles have no associated fields and when emitted from the dielectric do not have leave behind a...Experimental research performed at Texas Tech [16] showed that space charge must be included to properly characterize the multipactor evolution [22

Transverse mode coupling instability threshold with space charge and different wakefields

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

Balbekov, V.

Transverse mode coupling instability of a bunch with space charge and wake field is considered in frameworks of the boxcar model. Eigenfunctions of the bunch without wake are used as the basis for solution of the equations with the wake field included. Dispersion equation for the bunch eigentunes is obtained in the form of an infinite continued fraction. It is shown that influence of space charge on the instability essentially depends on the wake sign. In particular, threshold of the negative wake increases in absolute value until the space charge tune shift is rather small, and goes to zero atmore » higher space charge. The explanation of this behavior is developed by analysis of the bunch spectrum. As a result, a comparison of the results with published articles is represented.« less

Transverse mode coupling instability threshold with space charge and different wakefields

DOE PAGES

Balbekov, V.

2017-03-10

Transverse mode coupling instability of a bunch with space charge and wake field is considered in frameworks of the boxcar model. Eigenfunctions of the bunch without wake are used as the basis for solution of the equations with the wake field included. Dispersion equation for the bunch eigentunes is obtained in the form of an infinite continued fraction. It is shown that influence of space charge on the instability essentially depends on the wake sign. In particular, threshold of the negative wake increases in absolute value until the space charge tune shift is rather small, and goes to zero atmore » higher space charge. The explanation of this behavior is developed by analysis of the bunch spectrum. As a result, a comparison of the results with published articles is represented.« less

Circuital characterisation of space-charge motion with a time-varying applied bias

PubMed Central

Kim, Chul; Moon, Eun-Yi; Hwang, Jungho; Hong, Hiki

2015-01-01

Understanding the behaviour of space-charge between two electrodes is important for a number of applications. The Shockley-Ramo theorem and equivalent circuit models are useful for this; however, fundamental questions of the microscopic nature of the space-charge remain, including the meaning of capacitance and its evolution into a bulk property. Here we show that the microscopic details of the space-charge in terms of resistance and capacitance evolve in a parallel topology to give the macroscopic behaviour via a charge-based circuit or electric-field-based circuit. We describe two approaches to this problem, both of which are based on energy conservation: the energy-to-current transformation rule, and an energy-equivalence-based definition of capacitance. We identify a significant capacitive current due to the rate of change of the capacitance. Further analysis shows that Shockley-Ramo theorem does not apply with a time-varying applied bias, and an additional electric-field-based current is identified to describe the resulting motion of the space-charge. Our results and approach provide a facile platform for a comprehensive understanding of the behaviour of space-charge between electrodes. PMID:26133999

Extreme Spacecraft Charging in Polar Low Earth Orbit

NASA Technical Reports Server (NTRS)

Colson, Andrew D.; Minow, Joseph I.; Parker, L. Neergaard

2012-01-01

Spacecraft in low altitude, high inclination (including sun -synchronous) orbits are widely used for remote sensing of the Earth fs land surface and oceans, monitoring weather and climate, communications, scientific studies of the upper atmosphere and ionosphere, and a variety of other scientific, commercial, and military applications. These systems episodically charge to frame potentials in the kilovolt range when exposed to space weather environments characterized by a high flux of energetic (approx.10 fs kilovolt) electrons in regions of low background plasma density. Auroral charging conditions are similar in some ways to the space weather conditions in geostationary orbit responsible for spacecraft charging to kilovolt levels. We first review the physics of space environment interactions with spacecraft materials that control auroral charging rates and the anticipated maximum potentials that should be observed on spacecraft surfaces during disturbed space weather conditions. We then describe how the theoretical values compare to the observational history of extreme charging in auroral environments. Finally, a set of extreme DMSP charging events are described varying in maximum negative frame potential from approx.0.6 kV to approx.2 kV, focusing on the characteristics of the charging events that are of importance both to the space system designer and to spacecraft operators. The goal of the presentation is to bridge the gap between scientific studies of auroral charging and the need for engineering teams to understand how space weather impacts both spacecraft design and operations for vehicles on orbital trajectories that traverse auroral charging environments.

Simulation of Cascaded Longitudinal-Space-Charge Amplifier at the Fermilab Accelerator Science & Technology (Fast) Facility

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

Halavanau, A.; Piot, P.

2015-12-01

Cascaded Longitudinal Space Charge Amplifiers (LSCA) have been proposed as a mechanism to generate density modulation over a board spectral range. The scheme has been recently demonstrated in the optical regime and has confirmed the production of broadband optical radiation. In this paper we investigate, via numerical simulations, the performance of a cascaded LSCA beamline at the Fermilab Accelerator Science & Technology (FAST) facility to produce broadband ultraviolet radiation. Our studies are carried out using elegant with included tree-based grid-less space charge algorithm.

Extreme Spacecraft Charging in Polar Low Earth Orbit

NASA Technical Reports Server (NTRS)

Colson, Andrew D.; Minow, Joseph I.; NeergaardParker, Linda

2012-01-01

Spacecraft in low altitude, high inclination (including sun-synchronous) orbits are widely used for remote sensing of the Earth's land surface and oceans, monitoring weather and climate, communications, scientific studies of the upper atmosphere and ionosphere, and a variety of other scientific, commercial, and military applications. These systems episodically charge to frame potentials in the kilovolt range when exposed to space weather environments characterized by a high flux of energetic (10 s kilovolt) electrons in regions of low background plasma density which is similar in some ways to the space weather conditions in geostationary orbit responsible for spacecraft charging to kilovolt levels. We first review the physics of space environment interactions with spacecraft materials that control auroral charging rates and the anticipated maximum potentials that should be observed on spacecraft surfaces during disturbed space weather conditions. We then describe how the theoretical values compare to the observational history of extreme charging in auroral environments. Finally, a set of extreme DMSP charging events are described varying in maximum negative frame potential from 0.6 kV to 2 kV, focusing on the characteristics of the charging events that are of importance both to the space system designer and to spacecraft operators. The goal of the presentation is to bridge the gap between scientific studies of auroral charging and the need for engineering teams to understand how space weather impacts both spacecraft design and operations for vehicles on orbital trajectories that traverse auroral charging environments.

Space Weather Impacts on Spacecraft Design and Operations in Auroral Charging Environments

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Parker, Linda N.

2012-01-01

Spacecraft in low altitude, high inclination (including sun-synchronous) orbits are widely used for remote sensing of the Earth s land surface and oceans, monitoring weather and climate, communications, scientific studies of the upper atmosphere and ionosphere, and a variety of other scientific, commercial, and military applications. These systems are episodically exposed to environments characterized by a high flux of energetic (approx.1 to 10 s kilovolt) electrons in regions of very low background plasma density which is similar in some ways to the space weather conditions in geostationary orbit responsible for spacecraft charging to kilovolt levels. While it is well established that charging conditions in geostationary orbit are responsible for many anomalies and even spacecraft failures, to date there have been relatively few such reports due to charging in auroral environments. This presentation first reviews the physics of the space environment and its interactions with spacecraft materials that control auroral charging rates and the anticipated maximum potentials that should be observed on spacecraft surfaces during disturbed space weather conditions. We then describe how the theoretical values compare to the observational history of extreme charging in auroral environments and discuss how space weather impacts both spacecraft design and operations for vehicles on orbital trajectories that traverse auroral charging environments.

Mining CRRES IDM Pulse Data and CRRES Environmental Data to Improve Spacecraft Charging/Discharging Models and Guidelines

NASA Technical Reports Server (NTRS)

Brautigam, D. H.; Frederickson, A. R.

2004-01-01

One can truly predict the charging and pulsing in space over a year's time using only the physics that worked for periods of an hour and less in prior publications. All portions of the task were achieved, including the optional portion of determining a value for conductivity that best .t the data. Fortran statements were developed that are required for the NUMIT runs to work with this kind of data from space. In addition to developing the Fortran for NUMIT, simple correlations between the IDM pulsing history and the space radiation were observed because we now have a better characterization of the space radiation. The study showed that: (1) the new methods for measurement of charge storage and conduction in insulators provide the correct values to use for prediction of charging and pulsing in space; (2) the methods in NUMIT that worked well for time durations less than hours now work well for durations of months; (3) an average spectrum such as AE8 is probably not a good guide for predicting pulsing in space one must take time dependence into account in order to understand insulator pulsing; and (4) the old method for predicting pulse rates in space that was based on the CRRES data could be improved to include dependencies on material parameters.

Improving Charging-Breeding Simulations with Space-Charge Effects

NASA Astrophysics Data System (ADS)

Bilek, Ryan; Kwiatkowski, Ania; Steinbrügge, René

2016-09-01

Rare-isotope-beam facilities use Highly Charged Ions (HCI) for accelerators accelerating heavy ions and to improve measurement precision and resolving power of certain experiments. An Electron Beam Ion Trap (EBIT) is able to create HCI through successive electron impact, charge breeding trapped ions into higher charge states. CBSIM was created to calculate successive charge breeding with an EBIT. It was augmented by transferring it into an object-oriented programming language, including additional elements, improving ion-ion collision factors, and exploring the overlap of the electron beam with the ions. The calculation is enhanced with the effects of residual background gas by computing the space charge due to charge breeding. The program assimilates background species, ionizes and charge breeds them alongside the element being studied, and allows them to interact with the desired species through charge exchange, giving fairer overview of realistic charge breeding. Calculations of charge breeding will be shown for realistic experimental conditions. We reexamined the implementation of ionization energies, cross sections, and ion-ion interactions when charge breeding.

Varactor with integrated micro-discharge source

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

Elizondo-Decanini, Juan M.; Manginell, Ronald P.; Moorman, Matthew W.

2016-10-18

An apparatus that includes a varactor element and an integrated micro-discharge source is disclosed herein. In a general embodiment, the apparatus includes at least one np junction and at least one voltage source that is configured to apply voltage across the np junction. The apparatus further includes an aperture that extends through the np junction. When the voltage is applied across the np junction, gas in the aperture is ionized, forming a plasma, in turn causing a micro-discharge (of light, charge particles, and space charge) to occur. The light (charge particles, and space charge) impinges upon the surface of themore » np junction exposed in the aperture, thereby altering capacitance of the np junction. When used within an oscillator circuit, the effect of the plasma on the np-junction extends the capacitance changes of the np-junction and extends the oscillator frequency range in ways not possible by a conventional voltage controlled oscillator (VCO).« less

Review of Nuclear Physics Experiments for Space Radiation

NASA Technical Reports Server (NTRS)

Norbury, John W.; Miller, Jack; Adamczyk, Anne M.; Heilbronn, Lawrence H.; Townsend, Lawrence W.; Blattnig, Steve R.; Norman, Ryan B.; Guetersloh, Stephen B.; Zeitlin, Cary J.

2011-01-01

Human space flight requires protecting astronauts from the harmful effects of space radiation. The availability of measured nuclear cross section data needed for these studies is reviewed in the present paper. The energy range of interest for radiation protection is approximately 100 MeV/n to 10 GeV/n. The majority of data are for projectile fragmentation partial and total cross sections, including both charge changing and isotopic cross sections. The cross section data are organized into categories which include charge changing, elemental, isotopic for total, single and double differential with respect to momentum, energy and angle. Gaps in the data relevant to space radiation protection are discussed and recommendations for future experiments are made.

Optical Spectroscopy Of Charged Quantum Dot Molecules

NASA Astrophysics Data System (ADS)

Scheibner, M.; Bracker, A. S.; Stinaff, E. A.; Doty, M. F.; Gammon, D.; Ponomarev, I. V.; Reinecke, T. L.; Korenev, V. L.

2007-04-01

Coupling between two closely spaced quantum dots is observed by means of photoluminescence spectroscopy. Hole coupling is realized by rational crystal growth and heterostructure design. We identify molecular resonances of different excitonic charge states, including the important case of a doubly charged quantum dot molecule.

Self-consistent simulation of radio frequency multipactor on micro-grooved dielectric surface

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

Cai, Libing; Wang, Jianguo, E-mail: wanguiuc@mail.xjtu.edu.cn; Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024

2015-02-07

The multipactor plays a key role in the surface breakdown on the feed dielectric window irradiated by high power microwave. To study the suppression of multipactor, a 2D electrostatic PIC-MCC simulation code was developed. The space charge field, including surface deposited charge and multipactor electron charge field, is obtained by solving 2D Poisson's equation in time. Therefore, the simulation is self-consistent and does not require presetting a fixed space charge field. By using this code, the self-consistent simulation of the RF multipactor on the periodic micro-grooved dielectric surface is realized. The 2D space distributions of the multipactor electrons and spacemore » charge field are presented. From the simulation results, it can be found that only half slopes have multipactor discharge when the slope angle exceeds a certain value, and the groove presents a pronounced suppression effect on the multipactor.« less

MSFC/EV44 Natural Environment Capabilities

NASA Technical Reports Server (NTRS)

NeergaardParker, Linda; Willis, Emily M.; Minnow, Joseph I.; Coffey, Vic N.

2014-01-01

The Natural Environments Branch at Marshall Space Flight Center is an integral part of many NASA satellite and launch vehicle programs, providing analyses of the space and terrestrial environments that are used for program development efforts, operational support, and anomaly investigations. These capabilities include model development, instrument build and testing, analysis of space and terrestrial related data, spacecraft charging anomaly investigations, surface and internal charging modeling, space environment definition, and radiation assessments for electronic parts. All aspects of space and terrestrial design are implemented with the goal of devising missions that are successful from launch to operations in the space environment of LEO, polar, GEO, and interplanetary orbits.

Magnetic radiation shielding - An idea whose time has returned?

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

1991-01-01

One solution to the problem of shielding crew from particulate radiation in space is to use active electromagnetic shielding. Practical types of shield include the magnetic shield, in which a strong magnetic field diverts charged particles from the crew region, and the magnetic/electrostatic plasma shield, in which an electrostatic field shields the crew from positively charged particles, while a magnetic field confines electrons from the space plasma to provide charge neutrality. Advances in technology include high-strength composite materials, high-temperature superconductors, numerical computational solutions to particle transport in electromagnetic fields, and a technology base for construction and operation of large superconducting magnets. These advances make electromagnetic shielding a practical alternative for near-term future missions.

Materials Characterization at Utah State University: Facilities and Knowledge-base of Electronic Properties of Materials Applicable to Spacecraft Charging

NASA Technical Reports Server (NTRS)

Dennison, J. R.; Thomson, C. D.; Kite, J.; Zavyalov, V.; Corbridge, Jodie

2004-01-01

In an effort to improve the reliability and versatility of spacecraft charging models designed to assist spacecraft designers in accommodating and mitigating the harmful effects of charging on spacecraft, the NASA Space Environments and Effects (SEE) Program has funded development of facilities at Utah State University for the measurement of the electronic properties of both conducting and insulating spacecraft materials. We present here an overview of our instrumentation and capabilities, which are particularly well suited to study electron emission as related to spacecraft charging. These measurements include electron-induced secondary and backscattered yields, spectra, and angular resolved measurements as a function of incident energy, species and angle, plus investigations of ion-induced electron yields, photoelectron yields, sample charging and dielectric breakdown. Extensive surface science characterization capabilities are also available to fully characterize the samples in situ. Our measurements for a wide array of conducting and insulating spacecraft materials have been incorporated into the SEE Charge Collector Knowledge-base as a Database of Electronic Properties of Materials Applicable to Spacecraft Charging. This Database provides an extensive compilation of electronic properties, together with parameterization of these properties in a format that can be easily used with existing spacecraft charging engineering tools and with next generation plasma, charging, and radiation models. Tabulated properties in the Database include: electron-induced secondary electron yield, backscattered yield and emitted electron spectra; He, Ar and Xe ion-induced electron yields and emitted electron spectra; photoyield and solar emittance spectra; and materials characterization including reflectivity, dielectric constant, resistivity, arcing, optical microscopy images, scanning electron micrographs, scanning tunneling microscopy images, and Auger electron spectra. Further details of the instrumentation used for insulator measurements and representative measurements of insulating spacecraft materials are provided in other Spacecraft Charging Conference presentations. The NASA Space Environments and Effects Program, the Air Force Office of Scientific Research, the Boeing Corporation, NASA Graduate Research Fellowships, and the NASA Rocky Mountain Space Grant Consortium have provided support.

Through-Space Intervalence Charge Transfer as a Mechanism for Charge Delocalisation in Metal-Organic Frameworks.

PubMed

Hua, Carol; Doheny, Patrick William; Ding, Bowen; Chan, Bun; Yu, Michelle; Kepert, Cameron J; D'Alessandro, Deanna M

2018-05-04

Understanding the nature of charge transfer mechanisms in 3-dimensional Metal-Organic Frameworks (MOFs) is an important goal owing to the possibility of harnessing this knowledge to design conductive frameworks. These materials have been implicated as the basis for the next generation of technological devices for applications in energy storage and conversion, including electrochromic devices, electrocatalysts, and battery materials. After nearly two decades of intense research into MOFs, the mechanisms of charge transfer remain relatively poorly understood, and new strategies to achieve charge mobility remain elusive and challenging to experimentally explore, validate and model. We now demonstrate that aromatic stacking interactions in Zn(II) frameworks containing cofacial thiazolo[5,4-d]thiazole units lead to a mixed-valence state upon electrochemical or chemical reduction. This through-space Intervalence Charge Transfer (IVCT) phenomenon represents a new mechanism for charge delocalisation in MOFs. Computational modelling of the optical data combined with application of Marcus-Hush theory to the IVCT bands for the mixed-valence framework has enabled quantification of the degree of delocalisation using both in situ and ex situ electro- and spectro-electrochemical methods. A distance dependence for the through-space electron transfer has also been identified on the basis of experimental studies and computational calculations. This work provides a new window into electron transfer phenomena in 3-dimensional coordination space, of relevance to electroactive MOFs where new mechanisms for charge transfer are highly sought after, and to understanding biological light harvesting systems where through-space mixed-valence interactions are operative.

NASCAP user's manual

NASA Technical Reports Server (NTRS)

Mandell, M. J.; Harvey, J. M.; Katz, I.

1977-01-01

The NASCAP (NASA Charging Analyzer Program) code simulates the charging process for a complex object in either tenuous plasma or ground test environment. Detailed specifications needed to run the code are presented. The object definition section, OBJDEF, allows the test object to be easily defined in the cubic mesh. The test object is composed of conducting sections which may be wholly or partially covered with thin dielectric coatings. The potential section, POTENT, obtains the electrostatic potential in the space surrounding the object. It uses the conjugate gradient method to solve the finite element formulation of Poisson's equation. The CHARGE section of NASCAP treats charge redistribution among the surface cells of the object as well as charging through radiation bombardment. NASCAP has facilities for extensive graphical output, including several types of object display plots, potential contour plots, space charge density contour plots, current density plots, and particle trajectory plots.

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

Pang, Xiaoying; Rybarcyk, Larry

HPSim is a GPU-accelerated online multi-particle beam dynamics simulation tool for ion linacs. It was originally developed for use on the Los Alamos 800-MeV proton linac. It is a “z-code” that contains typical linac beam transport elements. The linac RF-gap transformation utilizes transit-time-factors to calculate the beam acceleration therein. The space-charge effects are computed using the 2D SCHEFF (Space CHarge EFFect) algorithm, which calculates the radial and longitudinal space charge forces for cylindrically symmetric beam distributions. Other space- charge routines to be incorporated include the 3D PICNIC and a 3D Poisson solver. HPSim can simulate beam dynamics in drift tubemore » linacs (DTLs) and coupled cavity linacs (CCLs). Elliptical superconducting cavity (SC) structures will also be incorporated into the code. The computational core of the code is written in C++ and accelerated using the NVIDIA CUDA technology. Users access the core code, which is wrapped in Python/C APIs, via Pythons scripts that enable ease-of-use and automation of the simulations. The overall linac description including the EPICS PV machine control parameters is kept in an SQLite database that also contains calibration and conversion factors required to transform the machine set points into model values used in the simulation.« less

Installation and Characterization of Charged Particle Sources for Space Environmental Effects Testing

NASA Technical Reports Server (NTRS)

Skevington, Jennifer L.

2010-01-01

Charged particle sources are integral devices used by Marshall Space Flight Center s Environmental Effects Branch (EM50) in order to simulate space environments for accurate testing of materials and systems. By using these sources inside custom vacuum systems, materials can be tested to determine charging and discharging properties as well as resistance to sputter damage. This knowledge can enable scientists and engineers to choose proper materials that will not fail in harsh space environments. This paper combines the steps utilized to build a low energy electron gun (The "Skevington 3000") as well as the methods used to characterize the output of both the Skevington 3000 and a manufactured Xenon ion source. Such characterizations include beam flux, beam uniformity, and beam energy. Both sources were deemed suitable for simulating environments in future testing.

Modeling Charge Collection in Detector Arrays

NASA Technical Reports Server (NTRS)

Hardage, Donna (Technical Monitor); Pickel, J. C.

2003-01-01

A detector array charge collection model has been developed for use as an engineering tool to aid in the design of optical sensor missions for operation in the space radiation environment. This model is an enhancement of the prototype array charge collection model that was developed for the Next Generation Space Telescope (NGST) program. The primary enhancements were accounting for drift-assisted diffusion by Monte Carlo modeling techniques and implementing the modeling approaches in a windows-based code. The modeling is concerned with integrated charge collection within discrete pixels in the focal plane array (FPA), with high fidelity spatial resolution. It is applicable to all detector geometries including monolithc charge coupled devices (CCDs), Active Pixel Sensors (APS) and hybrid FPA geometries based on a detector array bump-bonded to a readout integrated circuit (ROIC).

Transverse Phase Space Reconstruction and Emittance Measurement of Intense Electron Beams using a Tomography Technique

NASA Astrophysics Data System (ADS)

Stratakis, D.; Kishek, R. A.; Li, H.; Bernal, S.; Walter, M.; Tobin, J.; Quinn, B.; Reiser, M.; O'Shea, P. G.

2006-11-01

Tomography is the technique of reconstructing an image from its projections. It is widely used in the medical community to observe the interior of the human body by processing multiple x-ray images taken at different angles, A few pioneering researchers have adapted tomography to reconstruct detailed phase space maps of charged particle beams. Some questions arise regarding the limitations of tomography technique for space charge dominated beams. For instance is the linear space charge force a valid approximation? Does tomography equally reproduce phase space for complex, experimentally observed, initial particle distributions? Does tomography make any assumptions about the initial distribution? This study explores the use of accurate modeling with the particle-in-cell code WARP to address these questions, using a wide range of different initial distributions in the code. The study also includes a number of experimental results on tomographic phase space mapping performed on the University of Maryland Electron Ring (UMER).

Theory of Space Charge Limited Current in Fractional Dimensional Space

NASA Astrophysics Data System (ADS)

Zubair, Muhammad; Ang, L. K.

The concept of fractional dimensional space has been effectively applied in many areas of physics to describe the fractional effects on the physical systems. We will present some recent developments of space charge limited (SCL) current in free space and solid in the framework of fractional dimensional space which may account for the effect of imperfectness or roughness of the electrode surface. For SCL current in free space, the governing law is known as the Child-Langmuir (CL) law. Its analogy in a trap-free solid (or dielectric) is known as Mott-Gurney (MG) law. This work extends the one-dimensional CL Law and MG Law for the case of a D-dimensional fractional space with 0 < D <= 1 where parameter D defines the degree of roughness of the electrode surface. Such a fractional dimensional space generalization of SCL current theory can be used to characterize the charge injection by the imperfectness or roughness of the surface in applications related to high current cathode (CL law), and organic electronics (MG law). In terms of operating regime, the model has included the quantum effects when the spacing between the electrodes is small.

Space platform power system hardware testbed

NASA Technical Reports Server (NTRS)

Sable, D.; Patil, A.; Sizemore, T.; Deuty, S.; Noon, J.; Cho, B. H.; Lee, F. C.

1991-01-01

The scope of the work on the NASA Space Platform includes the design of a multi-module, multi-phase boost regulator, and a voltage-fed, push-pull autotransformer converter for the battery discharger. A buck converter was designed for the charge regulator. Also included is the associated mode control electronics for the charger and discharger, as well as continued development of a comprehensive modeling and simulation tool for the system. The design of the multi-module boost converter is discussed for use as a battery discharger. An alternative battery discharger design is discussed using a voltage-fed, push-pull autotransformer converter. The design of the charge regulator is explained using a simple buck converter. The design of the mode controller and effects of locating the bus filter capacitor bank 20 feet away from the power ORU are discussed. A brief discussion of some alternative topologies for battery charging and discharging is included. The power system modeling is described.

Deep Charging Evaluation of Satellite Power and Communication System Components

NASA Technical Reports Server (NTRS)

Schneider, T. A.; Vaughn, J. A.; Chu, B.; Wong, F.; Gardiner, G.; Wright, K. H.; Phillips, B.

2016-01-01

A set of deep charging tests has been carried out by NASA's Marshall Space Flight Center on subscale flight-like samples developed by Space Systems/Loral, LLC. The samples, which included solar array wire coupons, a photovoltaic cell coupon, and a coaxial microwave transmission cable, were placed in passive and active (powered) circuit configurations and exposed to electron radiation. The energy of the electron radiation was chosen to deeply penetrate insulating (dielectric) materials on each sample. Each circuit configuration was monitored to determine if potentially damaging electrostatic discharge events (arcs) were developed on the coupon as a result of deep charging. The motivation for the test, along with charging levels, experimental setup, sample details, and results will be discussed.

Open Up Your Newspaper with Advertising.

ERIC Educational Resources Information Center

Spielberger, Ronald E.

1980-01-01

Suggests ways the business office of a student newspaper can ease the conflicts between news and advertising space, including: raising advertising rates, selling ads only in uniform sizes, charging extra for premium space, selling special features, and selling space around a monthly calendar of special events. (TJ)

Interplay between efficiency and device architecture for small molecule organic solar cells.

PubMed

Williams, Graeme; Sutty, Sibi; Aziz, Hany

2014-06-21

Small molecule organic solar cells (OSCs) have experienced a resurgence of interest over their polymer solar cell counterparts, owing to their improved batch-to-batch (thus, cell-to-cell) reliability. In this systematic study on OSC device architecture, we investigate five different small molecule OSC structures, including the simple planar heterojunction (PHJ) and bulk heterojunction (BHJ), as well as several planar-mixed structures. The different OSC structures are studied over a wide range of donor:acceptor mixing concentrations to gain a comprehensive understanding of their charge transport behavior. Transient photocurrent decay measurements provide crucial information regarding the interplay between charge sweep-out and charge recombination, and ultimately hint toward space charge effects in planar-mixed structures. Results show that the BHJ/acceptor architecture, comprising a BHJ layer with high C60 acceptor content, generates OSCs with the highest performance by balancing charge generation with charge collection. The performance of other device architectures is largely limited by hole transport, with associated hole accumulation and space charge effects.

NASA's Technical Handbook for Avoiding On-Orbit ESD Anomalies Due to Internal Charging Effects

NASA Technical Reports Server (NTRS)

Whittlesey, Albert; Garrett, Henry B.

1996-01-01

This paper describes NASA-HDBK-4002, "Avoiding Problems Caused by Spacecraft On-Orbit Internal Charging Effects". The handbook includes a description of internal charging and why it is of concern to spacecraft designers. It also suggests how to determine when a project needs to consider internal spacecraft charging, it contains an electron penetration depth chart, rationale for a critical electron flux criterion, a worst-case geosynchronous electron plasma spectrum, general design guidelines, quantitative design guidelines, and a typical materials characteristics list. Appendices include a listing of some environment codes, electron transport codes, a discussion of geostationary electron plasma environments, a brief description of electron beam and other materials tests, and transient susceptibility tests. The handbook will be in the web page, hftp://standards.nasa.gov. A prior document, NASA TP2361 "Design Guidelines for Assessing and controlling Spacecraft Charging Effects", 1984, is in use to describe mitigation techniques for the effects of surface charging of satellites in space plasma environments. HDBK-4002 is meant to complement 2361 and together, the pair of documents describe both cause and mitigation designs for problems caused by energetic space plasmas.

High-order space charge effects using automatic differentiation

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

Reusch, Michael F.; Bruhwiler, David L.; Computer Accelerator Physics Conference Williamsburg, Virginia 1996

1997-02-01

The Northrop Grumman Topkark code has been upgraded to Fortran 90, making use of operator overloading, so the same code can be used to either track an array of particles or construct a Taylor map representation of the accelerator lattice. We review beam optics and beam dynamics simulations conducted with TOPKARK in the past and we present a new method for modeling space charge forces to high-order with automatic differentiation. This method generates an accurate, high-order, 6-D Taylor map of the phase space variable trajectories for a bunched, high-current beam. The spatial distribution is modeled as the product of amore » Taylor Series times a Gaussian. The variables in the argument of the Gaussian are normalized to the respective second moments of the distribution. This form allows for accurate representation of a wide range of realistic distributions, including any asymmetries, and allows for rapid calculation of the space charge fields with free space boundary conditions. An example problem is presented to illustrate our approach.« less

Homogenous charge compression ignition engine having a cylinder including a high compression space

DOEpatents

Agama, Jorge R.; Fiveland, Scott B.; Maloney, Ronald P.; Faletti, James J.; Clarke, John M.

2003-12-30

The present invention relates generally to the field of homogeneous charge compression engines. In these engines, fuel is injected upstream or directly into the cylinder when the power piston is relatively close to its bottom dead center position. The fuel mixes with air in the cylinder as the power piston advances to create a relatively lean homogeneous mixture that preferably ignites when the power piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. Thus, the present invention divides the homogeneous charge between a controlled volume higher compression space and a lower compression space to better control the start of ignition.

Spacecraft dielectric material properties and spacecraft charging

NASA Technical Reports Server (NTRS)

Frederickson, A. R.; Wall, J. A.; Cotts, D. B.; Bouquet, F. L.

1986-01-01

The physics of spacecraft charging is reviewed, and criteria for selecting and testing semiinsulating polymers (SIPs) to avoid charging are discussed and illustrated. Chapters are devoted to the required properties of dielectric materials, the charging process, discharge-pulse phenomena, design for minimum pulse size, design to prevent pulses, conduction in polymers, evaluation of SIPs that might prevent spacecraft charging, and the general response of dielectrics to space radiation. SIPs characterized include polyimides, fluorocarbons, thermoplastic polyesters, poly(alkanes), vinyl polymers and acrylates, polymers containing phthalocyanine, polyacene quinones, coordination polymers containing metal ions, conjugated-backbone polymers, and 'metallic' conducting polymers. Tables summarizing the results of SIP radiation tests (such as those performed for the NASA Galileo Project) are included.

Electron Emission Properties of Insulator Materials Pertinent to the International Space Station

NASA Technical Reports Server (NTRS)

Thomson, C. D.; Zavyalov, V.; Dennison, J. R.; Corbridge, Jodie

2004-01-01

We present the results of our measurements of the electron emission properties of selected insulating and conducting materials used on the International Space Station (ISS). Utah State University (USU) has performed measurements of the electron-, ion-, and photon-induced electron emission properties of conductors for a few years, and has recently extended our capabilities to measure electron yields of insulators, allowing us to significantly expand current spacecraft material charging databases. These ISS materials data are used here to illustrate our various insulator measurement techniques that include: i) Studies of electron-induced secondary and backscattered electron yield curves using pulsed, low current electron beams to minimize deleterious affects of insulator charging. ii) Comparison of several methods used to determine the insulator 1st and 2nd crossover energies. These incident electron energies induce unity total yield at the transition between yields greater than and less than one with either negative or positive charging, respectively. The crossover energies are very important in determining both the polarity and magnitude of spacecraft surface potentials. iii) Evolution of electron emission energy spectra as a function of insulator charging used to determine the surface potential of insulators. iv) Surface potential evolution as a function of pulsed-electron fluence to determine how quickly insulators charge, and how this can affect subsequent electron yields. v) Critical incident electron energies resulting in electrical breakdown of insulator materials and the effect of breakdown on subsequent emission, charging and conduction. vi) Charge-neutralization techniques such as low-energy electron flooding and UV light irradiation to dissipate both positive and negative surface potentials during yield measurements. Specific ISS materials being tested at USU include chromic and sulfuric anodized aluminum, RTV-silicone solar array adhesives, solar cell cover glasses, Kapton, and gold. Further details of the USU testing facilities, the instrumentation used for insulator measurements, and the NASA/SEE Charge Collector materials database are provided in other Spacecraft Charging Conference presentations (Dennison, 2003b). The work presented was supported in part by the NASA Space Environments and Effects (SEE) Program, the Boeing Corporation, and a NASA Graduate Fellowship. Samples were supplied by Boeing, the Environmental Effects Group at Marshall Space Flight Center, and Sheldahl, Inc.

Space station: Cost and benefits

NASA Technical Reports Server (NTRS)

1983-01-01

Costs for developing, producing, operating, and supporting the initial space station, a 4 to 8 man space station, and a 4 to 24 man space station are estimated and compared. These costs include contractor hardware; space station assembly and logistics flight costs; and payload support elements. Transportation system options examined include orbiter modules; standard and extended duration STS fights; reusable spacebased perigee kick motor OTV; and upper stages. Space station service charges assessed include crew hours; energy requirements; payload support module storage; pressurized port usage; and OTV service facility. Graphs show costs for science missions, space processing research, small communication satellites; large GEO transportation; OVT launch costs; DOD payload costs, and user costs.

Three-dimensional relativistic field-electron interaction in a multicavity high-power klystron. 1: Basic theory

NASA Technical Reports Server (NTRS)

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.

AMS in payload bay viewed from Mir Space Station

NASA Image and Video Library

2016-08-24

STS091-367-033 (2-12 June 1998) --- This photo of the Space Shuttle Discovery's aft section features the Alpha Magnetic Spectrometer (AMS), as seen from Russia's Mir space station, docked with Discovery at the time. AMS is the first large-magnet experiment ever placed in Earth orbit. The scientific goal of this high-energy physics experiment is to increase our understanding of the composition and origin of the universe. It is designed to search for and measure charged particles, including antimatter, outside Earth's atmosphere. The charge of such particles can be identified only by their trajectories in a magnetic field.

A Study of the Nature and Origins of Pyroelectricity and Piezoelectricity in Polyvinylidenefluoride and Its Co-Polymers.

DTIC Science & Technology

1980-01-01

OF THIS PAOE(3tn Dea afm 20. Contd. It is possible that space charges are also present in the’film. However, the distribution of space charges in the...the discontinuities so that space charge effects may cause field perturbations. On the other hand, the corona charging procedure may drive ions into...trapped space charge effects; (iv) tunnelling of charge from the electrodes to empty traps; (v) hopping of charge carriers through localized states. The

Numerical Studies of High-Intensity Injection Painting for Project X

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

Drozhdin, A.I.; Vorobiev, L.G.; Johnson, D.E.

Injection phase space painting enables the mitigation of space charge and stability issues, and will be indispensable for the Project-X at Fermilab [1], delivering high-intensity proton beams to HEP experiments. Numerical simulations of multi-turn phase space painting have been performed for the FNAL Recycler Ring, including a self-consistent space charge model. The goal of our studies was to study the injection painting with inclusion of 3D space charge, using the ORBIT tracking code. In a current scenario the painting lasts for 110 turns, twice faster, than we considered in this paper. The optimal wave-forms for painting kickers, which ensure themore » flatter phase distributions, should be found. So far we used a simplified model for painting kicker strength (implemented as the 'ideal bump' in ORBIT). We will include a more realistic field map for the chicane magnets. Additional stripping simulations will be combined. We developed a block for longitudinal painting, which works with arbitrary notches in incoming micro-bunch buckets. The appropriate choice of the amplitude of the second harmonic of RF field will help to flatten the RF-bucket contours, as was demonstrated in 1D simulations. Non-linear lattice issue will be also addressed.« less

New methods in WARP, a particle-in-cell code for space-charge dominated beams

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

Grote, D., LLNL

1998-01-12

The current U.S. approach for a driver for inertial confinement fusion power production is a heavy-ion induction accelerator; high-current beams of heavy ions are focused onto the fusion target. The space-charge of the high-current beams affects the behavior more strongly than does the temperature (the beams are described as being ``space-charge dominated``) and the beams behave like non-neutral plasmas. The particle simulation code WARP has been developed and used to study the transport and acceleration of space-charge dominated ion beams in a wide range of applications, from basic beam physics studies, to ongoing experiments, to fusion driver concepts. WARP combinesmore » aspects of a particle simulation code and an accelerator code; it uses multi-dimensional, electrostatic particle-in-cell (PIC) techniques and has a rich mechanism for specifying the lattice of externally applied fields. There are both two- and three-dimensional versions, the former including axisymmetric (r-z) and transverse slice (x-y) models. WARP includes a number of novel techniques and capabilities that both enhance its performance and make it applicable to a wide range of problems. Some of these have been described elsewhere. Several recent developments will be discussed in this paper. A transverse slice model has been implemented with the novel capability of including bends, allowing more rapid simulation while retaining essential physics. An interface using Python as the interpreter layer instead of Basis has been developed. A parallel version of WARP has been developed using Python.« less

Method of measuring the dc electric field and other tokamak parameters

DOEpatents

Fisch, Nathaniel J.; Kirtz, Arnold H.

1992-01-01

A method including externally imposing an impulsive momentum-space flux to perturb hot tokamak electrons thereby producing a transient synchrotron radiation signal, in frequency-time space, and the inference, using very fast algorithms, of plasma parameters including the effective ion charge state Z.sub.eff, the direction of the magnetic field, and the position and width in velocity space of the impulsive momentum-space flux, and, in particular, the dc toroidal electric field.

14 CFR 1215.110 - User cancellation of all services.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false User cancellation of all services. 1215.110 Section 1215.110 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA...-launch activities, services, and mission documentation not included in that charge. The user will remain...

14 CFR 1215.110 - User cancellation of all services.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false User cancellation of all services. 1215.110 Section 1215.110 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA...-launch activities, services, and mission documentation not included in that charge. The user will remain...

14 CFR 1215.110 - User cancellation of all services.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false User cancellation of all services. 1215.110 Section 1215.110 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA...-launch activities, services, and mission documentation not included in that charge. The user will remain...

14 CFR 1215.110 - User cancellation of all services.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true User cancellation of all services. 1215.110 Section 1215.110 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA...-launch activities, services, and mission documentation not included in that charge. The user will remain...

Design of a 2 kA, 30 fs Rf-Photoinjector for Waterbag Compression

NASA Astrophysics Data System (ADS)

van der Geer, S. B.; Luiten, O. J.; de Loos, M. J.

Because uniformly filled ellipsoidal ‘waterbag’ bunches have linear self-fields in all dimensions, they do not suffer from space-charge induced brightness degradation. This in turn allows very efficient longitudinal compression of high-brightness bunches at sub or mildly relativistic energies, a parameter regime inaccessible up to now due to detrimental effects of non-linear space-charge forces. To demonstrate the feasibility of this approach, we investigate ballistic bunching of 1 MeV, 100 pC waterbag electron bunches, created in a half-cell rf-photogun, by means of a two-cell booster-compressor. Detailed GPT simulations of this table-top set-up are presented, including realistic fields, 3D space-charge effects, path-length differences and image charges at the cathode. It is shown that with a single 10MW S-band klystron and fields of 100 MV/m, 2kA peak current is attainable with a pulse duration of only 30 fs at a transverse normalized emittance of 1.5 μm.

Space charge effect in spectrometers of ion mobility increment with cylindrical drift chamber.

PubMed

Elistratov, A A; Sherbakov, L A

2007-01-01

We have amplified the model for the drift of ions under a non-uniform high-frequency electric field by taking space charge effect into account. By this means, we have investigated the effect of space charge on the dynamics of a single type of ions in a spectrometer of ion mobility increment with a cylindrical drift chamber. The counteraction of the space charge effect and the focusing effect is investigated. The output ion current saturation caused by the effect of the space charge is observed. The shape of the ion peak taking into consideration the space charge effect has been obtained. We show that the effect of the space charge is sufficient for the relative ion density greater than 10 ppt by order of magnitude (for a cylindrical geometry spectrometer with typical parameters).

Systematic Improvement of Potential-Derived Atomic Multipoles and Redundancy of the Electrostatic Parameter Space.

PubMed

Jakobsen, Sofie; Jensen, Frank

2014-12-09

We assess the accuracy of force field (FF) electrostatics at several levels of approximation from the standard model using fixed partial charges to conformational specific multipole fits including up to quadrupole moments. Potential-derived point charges and multipoles are calculated using least-squares methods for a total of ∼1000 different conformations of the 20 natural amino acids. Opposed to standard charge fitting schemes the procedure presented in the current work employs fitting points placed on a single isodensity surface, since the electrostatic potential (ESP) on such a surface determines the ESP at all points outside this surface. We find that the effect of multipoles beyond partial atomic charges is of the same magnitude as the effect due to neglecting conformational dependency (i.e., polarizability), suggesting that the two effects should be included at the same level in FF development. The redundancy at both the partial charge and multipole levels of approximation is quantified. We present an algorithm which stepwise reduces or increases the dimensionality of the charge or multipole parameter space and provides an upper limit of the ESP error that can be obtained at a given truncation level. Thereby, we can identify a reduced set of multipole moments corresponding to ∼40% of the total number of multipoles. This subset of parameters provides a significant improvement in the representation of the ESP compared to the simple point charge model and close to the accuracy obtained using the complete multipole parameter space. The selection of the ∼40% most important multipole sites is highly transferable among different conformations, and we find that quadrupoles are of high importance for atoms involved in π-bonding, since the anisotropic electric field generated in such regions requires a large degree of flexibility.

8th Spacecraft Charging Technology Conference

NASA Technical Reports Server (NTRS)

Minor, J. L. (Compiler)

2004-01-01

The 8th Spacecraft Charging Technology Conference was held in Huntsville, Alabama, October 20-24, 2003. Hosted by NASA s Space Environments and Effects (SEE) Program and co-sponsored by the Air Force Research Laboratory (AFRL) and the European Space Agency (ESA), the 2003 conference saw attendance from eleven countries with over 65 oral papers and 18 poster papers. Presentation topics highlighted the latest in spacecraft charging mitigation techniques and on-orbit investigations, including: Plasma Propulsion and Tethers; Ground Testing Techniques; Interactions of Spacecraft and Systems With the Natural and Induced Plasma Environment; Materials Characterizations; Models and Computer Simulations; Environment Specifications; Current Collection and Plasma Probes in Space Plasmas; On-Orbit Investigations. A round-table discussion of international standards regarding electrostatic discharge (ESD) testing was also held with the promise of continued discussions in the off years and an official continuation at the next conference.

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

Hong, Woo-Pyo; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180–3590

The influence of electron spin-interaction on the propagation of the electrostatic space-charge quantum wave is investigated in a cylindrically bounded quantum plasma. The dispersion relation of the space-charge quantum electrostatic wave is derived including the influence of the electron spin-current in a cylindrical waveguide. It is found that the influence of electron spin-interaction enhances the wave frequency for large wave number regions. It is shown that the wave frequencies with higher-solution modes are always smaller than those with lower-solution modes in small wave number domains. In addition, it is found that the wave frequency increases with an increase of themore » radius of the plasma cylinder as well as the Fermi wave number. We discuss the effects due to the quantum and geometric on the variation of the dispersion properties of the space-charge plasma wave.« less

The influence of space charge shielding on dielectric multipactor

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

Chang, C.; Liu, G. Z.; Tang, C. X.

2009-05-15

A model of space charge influenced by multipactor electrons and plasma has been established. The positive space charge potential/field for vacuum dielectric multipactor is analytically studied. After considering the plasma, the positive space charge field is further shielded, and multipactor saturates at higher surface accumulated field, compared with that for only considering multipactor electrons. The negative space charge potential/field for dielectric breakdown at high pressure is analyzed. It is found that the negative potential can be nonmonotonously varied, forming a minimum potential well.

Research-Based Monitoring, Prediction, and Analysis Tools of the Spacecraft Charging Environment for Spacecraft Users

NASA Technical Reports Server (NTRS)

Zheng, Yihua; Kuznetsova, Maria M.; Pulkkinen, Antti A.; Maddox, Marlo M.; Mays, Mona Leila

2015-01-01

The Space Weather Research Center (http://swrc. gsfc.nasa.gov) at NASA Goddard, part of the Community Coordinated Modeling Center (http://ccmc.gsfc.nasa.gov), is committed to providing research-based forecasts and notifications to address NASA's space weather needs, in addition to its critical role in space weather education. It provides a host of services including spacecraft anomaly resolution, historical impact analysis, real-time monitoring and forecasting, tailored space weather alerts and products, and weekly summaries and reports. In this paper, we focus on how (near) real-time data (both in space and on ground), in combination with modeling capabilities and an innovative dissemination system called the integrated Space Weather Analysis system (http://iswa.gsfc.nasa.gov), enable monitoring, analyzing, and predicting the spacecraft charging environment for spacecraft users. Relevant tools and resources are discussed.

Spacecraft Charging and Auroral Boundary Predictions in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Minow, Joseph I.

2016-01-01

Auroral charging of spacecraft is an important class of space weather impacts on technological systems in low Earth orbit. In order for space weather models to accurately specify auroral charging environments, they must provide the appropriate plasma environment characteristics responsible for charging. Improvements in operational space weather prediction capabilities relevant to charging must be tested against charging observations.

Single bunch transverse instability in a circular accelerator with chromaticity and space charge

DOE PAGES

Balbekov, V.

2015-10-21

The transverse instability of a bunch in a circular accelerator is elaborated in this paper. A new tree-modes model is proposed and developed to describe the most unstable modes of the bunch. This simple and flexible model includes chromaticity and space charge, and can be used with any bunch and wake forms. The dispersion equation for the bunch eigentunes is obtained in form of a third-order algebraic equation. The known head-tail and TMCI modes appear as the limiting cases which are distinctly bounded at zero chromaticity only. It is shown that the instability parameters depend only slightly on the bunchmore » model but they are rather sensitive to the wake shape. In particular, space charge effects are investigated in the paper and it is shown that their influence depends on sign of wake field enhancing the bunch stability if the wake is negative. In addition, the resistive wall wake is considered in detail including a comparison of single and collective effects. A comparison of the results with earlier publications is carried out.« less

14 CFR § 1215.110 - User cancellation of all services.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false User cancellation of all services. § 1215.110 Section § 1215.110 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING... of pre-launch activities, services, and mission documentation not included in that charge. The user...

Charge-conjugation symmetric complete impulse approximation for the pion electromagnetic form factor in the covariant spectator theory

DOE PAGES

Biernat, Elmar P.; Gross, Franz; Peña, M. T.; ...

2015-10-26

The pion form factor is calculated in the framework of the charge-conjugation invariant covariant spectator theory. This formalism is established in Minkowski space, and the calculation is set up in momentum space. In a previous calculation we included only the leading pole coming from the spectator quark (referred to as the relativistic impulse approximation). In this study we also include the contributions from the poles of the quark which interacts with the photon and average over all poles in both the upper and lower half-planes in order to preserve charge conjugation invariance (referred to as the C-symmetric complete impulse approximation).more » We find that for small pion mass these contributions are significant at all values of the four-momentum transfer Q 2 but, surprisingly, do not alter the shape obtained from the spectator poles alone.« less

SHIELDS Final Technical Report

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

Jordanova, Vania Koleva

Predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure, i.e. “space weather”, remains a big space physics challenge. A new capability was developed at Los Alamos National Laboratory (LANL) to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. This framework simulates the dynamics of the Surface Charging Environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- and micro-scale. In addition to using physics-based models (like RAM-SCB, BATS-R-US, and iPIC3D), new data assimilation techniques employing data frommore » LANL instruments on the Van Allen Probes and geosynchronous satellites were developed. An order of magnitude improvement in the accuracy in the simulation of the spacecraft surface charging environment was thus obtained. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code and to evaluate anomalies' relation to SCE dynamics. Such diagnostics is critically important when performing forensic analyses of space-system failures.« less

High-order space charge effects using automatic differentiation

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

Reusch, M.F.; Bruhwiler, D.L.

1997-02-01

The Northrop Grumman Topkark code has been upgraded to Fortran 90, making use of operator overloading, so the same code can be used to either track an array of particles or construct a Taylor map representation of the accelerator lattice. We review beam optics and beam dynamics simulations conducted with TOPKARK in the past and we present a new method for modeling space charge forces to high-order with automatic differentiation. This method generates an accurate, high-order, 6-D Taylor map of the phase space variable trajectories for a bunched, high-current beam. The spatial distribution is modeled as the product of amore » Taylor Series times a Gaussian. The variables in the argument of the Gaussian are normalized to the respective second moments of the distribution. This form allows for accurate representation of a wide range of realistic distributions, including any asymmetries, and allows for rapid calculation of the space charge fields with free space boundary conditions. An example problem is presented to illustrate our approach. {copyright} {ital 1997 American Institute of Physics.}« less

Data Products From Particle Detectors On-Board NOAA's Newest Space Weather Monitor

NASA Astrophysics Data System (ADS)

Kress, B. T.; Rodriguez, J. V.; Onsager, T. G.

2017-12-01

NOAA's newest Geostationary Operational Environmental Satellite, GOES-16, was launched on 19 November 2016. Instrumentation on-board GOES-16 includes the new Space Environment In-Situ Suite (SEISS), which has been collecting data since 8 January 2017. SEISS is composed of five magnetospheric particle sensor units: an electrostatic analyzer for measuring 30 eV - 30 keV ions and electrons (MPS-LO), a high energy particle sensor (MPS-HI) that measures keV to MeV electrons and protons, east and west facing Solar and Galactic Proton Sensor (SGPS) units with 13 differential channels between 1-500 MeV, and an Energetic Heavy Ion Sensor (EHIS) that measures 30 species of heavy ions (He-Ni) in five energy bands in the 10-200 MeV/nuc range. Measurement of low energy magnetospheric particles by MPS-LO and heavy ions by EHIS are new capabilities not previously flown on the GOES system. Real-time data from GOES-16 will support space weather monitoring and first-principles space weather modeling by NOAA's Space Weather Prediction Center (SWPC). Space weather level 2+ data products under development at NOAA's National Centers for Environmental Information (NCEI) include the Solar Energetic Particle (SEP) Event Detection algorithm. Legacy components of the SEP event detection algorithm (currently produced by SWPC) include the Solar Radiation Storm Scales. New components will include, e.g., event fluences. New level 2+ data products also include the SEP event Linear Energy Transfer (LET) Algorithm, for transforming energy spectra from EHIS into LET spectra, and the Density and Temperature Moments and Spacecraft Charging algorithm. The moments and charging algorithm identifies electron and ion signatures of spacecraft surface (frame) charging in the MPS-LO fluxes. Densities and temperatures from MPS-LO will also be used to support a magnetopause crossing detection algorithm. The new data products will provide real-time indicators of potential radiation hazards for the satellite community and data for future studies of space weather effects. This presentation will include an overview of these algorithms and examples of their performance during recent co-rotation interaction region (CIR) associated radiation belt enhancements and a solar particle event on 14-15 July 2017.

Space charge effects on the dielectric response of polymer nanocomposites

NASA Astrophysics Data System (ADS)

Shen, Zhong-Hui; Wang, Jian-Jun; Zhang, Xin; Lin, Yuanhua; Nan, Ce-Wen; Chen, Long-Qing; Shen, Yang

2017-08-01

Adding high-κ ceramic nanoparticles into polymers is a general strategy to improve the performances in energy storage. Classic effective medium theories may fail to predict the effective permittivity in polymer nanocomposites wherein the space charge effects are important. In this work, a computational model is developed to understand the space charge effects on the frequency-dependent dielectric properties including the real permittivity and the loss for polymer nanocomposites with both randomly distributed and aggregated nanoparticle fillers. It is found that the real permittivity of the SrTiO3/polyethylene (12% SrTiO3 in volume fraction) nanocomposite can be increased to as high as 60 when there is nanoparticle aggregation and the ion concentration in the bulk polymer is around 1016 cm-3. This model can be employed to quantitatively predict the frequency-dependent dielectric properties for polymer nanocomposites with arbitrary microstructures.

Space Weather Monitoring for ISS Geomagnetic Storm Studies

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Parker, Neergaard

2013-01-01

The International Space Station (ISS) space environments community utilizes near real time space weather data to support a variety of ISS engineering and science activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS since 2006 to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to electrostatic current collection from the plasma environment (spacecraft charging) and inductive (vxB) effects from the vehicle motion across the Earth s magnetic field. An ongoing effort is to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and investigate auroral charging of the vehicle as it passes through regions of precipitating auroral electrons. This work is challenged by restrictions on FPMU operations that limit observation time to less than about a third of a year. As a result, FPMU campaigns ranging in length from a few days to a few weeks are typically scheduled weeks in advance for ISS engineering and payload science activities. In order to capture geomagnetic storm data under these terms, we monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have successfully captured FPMU data during a number of geomagnetic storm periods including periods with ISS auroral charging. This presentation will describe the strategies and challenges in capturing FPMU data during geomagnetic storms, the near real time space weather resources utilized for monitoring the space weather environment, and provide examples of auroral charging data obtained during storm operations.

Calculation of total cross sections for charge exchange in molecular collisions

NASA Technical Reports Server (NTRS)

Ioup, J.

1979-01-01

Areas of investigation summarized include nitrogen ion-nitrogen molecule collisions; molecular collisions with surfaces; molecular identification from analysis of cracking patterns of selected gases; computer modelling of a quadrupole mass spectrometer; study of space charge in a quadrupole; transmission of the 127 deg cylindrical electrostatic analyzer; and mass spectrometer data deconvolution.

Combined effects of space charge and energetic disorder on photocurrent efficiency loss of field-dependent organic photovoltaic devices

NASA Astrophysics Data System (ADS)

Yoon, Sangcheol; Park, Byoungchoo; Hwang, Inchan

2015-11-01

The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole-Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers.

Characteristics of space charge formed in a laminated LDPE/EVA dielectric under DC stress

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

Tanaka, Toshikatsu; Kisanuki, Osamu; Sakata, Masataka

1996-12-31

A laser-induced pressure pulse (LIPP) method was used for measuring the space charge distribution of LDPE/EVA laminate dielectrics under dc stress. The constant voltage up to {+-}20 kV was applied to a side of the laminates of 0.5 mm thickness for 30 minutes. The other side is grounded. When the amount of space charge was measured by LIPP, both sides were virtually grounded. Space charge built up in or near the interface between LDPE and EVA was mainly investigated. Positive and negative voltage was applied to the side of LDPE in the laminates. It was clarified that the space chargemore » was larger in case of LDPE negatively biased than in case of LDPE positively biased. The density of the space charge ranged around 1 nC/mm{sup 3}. The formation of interfacial space charge is analyzed.« less

Space experiments with particle accelerators

NASA Technical Reports Server (NTRS)

Obayashi, T.; Kawashima, N.; Kuriki, K.; Nagatomo, M.; Ninomiya, K.; Sasaki, S.; Roberts, W. T.; Chappell, C. R.; Reasoner, D. L.; Garriott, O. K.;

14 CFR 1215.113 - User charges.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false User charges. 1215.113 Section 1215.113 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA RELAY SATELLITE SYSTEM... shall reimburse NASA the sum of the charges for standard and mission-unique services. Charges will be...

Light intensity dependence of open-circuit voltage and short-circuit current of polymer/fullerene solar cells

NASA Astrophysics Data System (ADS)

Koster, L. Jan A.; Mihailetchi, Valentin D.; Ramaker, Robert; Xie, Hangxing; Blom, Paul W. M.

2006-04-01

The open-circuit voltage (Voc) of polymer/fullerene bulk heterojunction solar cells is investigated as a function of light intensity for different temperatures. The observed photogenerated current and V oc are at variance with classical p-n junctionbased models. The influence of light intensity and recombination strength on V oc is consistently explained by a model based on the notion that the quasi-Fermi levels are constant throughout the device, including both drift and diffusion of charge carriers. The light intensity dependence of the short-circuit current density (J sc) is also addressed. A typical feature of polymer/fullerene based solar cells is that Jsc does not scale exactly linearly with light intensity (I). Instead, a power law relationship is found given by Jsc~ Iα, where α ranges from 0.9 to 1. In a number of reports this deviation from unity is attributed to the occurrence of bimolecular recombination. We demonstrate that the dependence of the photocurrent in bulk heterojunction solar cells is governed by the build-up of space charge in the device. The occurrence of space-charge stems from the difference in charge carrier mobility of electrons and holes. In blends of poly(3-hexylthiophene) and 6,6- phenyl C61-butyric acid methyl ester this mobility difference can be tuned in between one and three orders of magnitude, depending on the annealing conditions. This allows us to experimentally verify the relation between space charge build-up and intensity dependence of Jsc. Model calculations confirm that bimolecular recombination leads only to a typical loss of 1% of all free charge carriers at Jsc for these devices. Therefore, bimolecular recombination plays only a minor role as compared to the effect of space charge in the intensity dependence of J sc.

Theoretical models for electron conduction in polymer systems—I. Macroscopic calculations of d.c. transient conductivity after pulse irradiation

NASA Astrophysics Data System (ADS)

Bartczak, Witold M.; Kroh, Jerzy

The simulation of the transient d.c. conductivity in a quasi one-dimensional system of charges produced by a pulse of ionizing radiation in a solid sample has been performed. The simulation is based on the macroscopic conductivity equations and can provide physical insight into d.c. conductivity measurements, particularly for the case of transient currents in samples with internal space charge. We consider the system of mobile (negative) and immobile (positive) charges produced by a pulse of ionizing radiation in the sample under a fixed external voltage V0. The presence of space charge results in an electric field which is a function of both the spatial and the time variable: E( z, t). Given the space charge density, the electric field can be calculated from the Poisson equation. However, for an arbitrary space charge distribution, the corresponding equations can only be solved numerically. The two non-trivial cases for which approximate analytical solutions can be provided are: (i) The density of the current carriers n( z, t) is negligible in comparison with the density of immobile space charge N( z). A general analytical solution has been found for this case using Green's functions. The solutions for two cases, viz. the homogeneous distribution of space charge N( z) = N, and the non-homogeneous exponential distribution N( z) = A exp(- Bz), have been separately discussed. (ii) The space charge created in the pulse without any space charge present prior to the irradiation.

Applying simulation model to uniform field space charge distribution measurements by the PEA method

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

Liu, Y.; Salama, M.M.A.

1996-12-31

Signals measured under uniform fields by the Pulsed Electroacoustic (PEA) method have been processed by the deconvolution procedure to obtain space charge distributions since 1988. To simplify data processing, a direct method has been proposed recently in which the deconvolution is eliminated. However, the surface charge cannot be represented well by the method because the surface charge has a bandwidth being from zero to infinity. The bandwidth of the charge distribution must be much narrower than the bandwidths of the PEA system transfer function in order to apply the direct method properly. When surface charges can not be distinguished frommore » space charge distributions, the accuracy and the resolution of the obtained space charge distributions decrease. To overcome this difficulty a simulation model is therefore proposed. This paper shows their attempts to apply the simulation model to obtain space charge distributions under plane-plane electrode configurations. Due to the page limitation for the paper, the charge distribution originated by the simulation model is compared to that obtained by the direct method with a set of simulated signals.« less

Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect

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

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr

The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order.more » It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.« less

Meeting the Grand Challenge of Protecting Astronauts Health: Electrostatic Active Space Radiation Shielding for Deep Space Missions

NASA Technical Reports Server (NTRS)

Tripathi, Ram K.

2016-01-01

This report describes the research completed during 2011 for the NASA Innovative Advanced Concepts (NIAC) project. The research is motivated by the desire to safely send humans in deep space missions and to keep radiation exposures within permitted limits. To this end current material shielding, developed for low earth orbit missions, is not a viable option due to payload and cost penalties. The active radiation shielding is the path forward for such missions. To achieve active space radiation shielding innovative large lightweight gossamer space structures are used. The goal is to deflect enough positive ions without attracting negatively charged plasma and to investigate if a charged Gossamer structure can perform charge deflections without significant structural instabilities occurring. In this study different innovative configurations are explored to design an optimum active shielding. In addition, to establish technological feasibility experiments are performed with up to 10kV of membrane charging, and an electron flux source with up to 5keV of energy and 5mA of current. While these charge flux energy levels are much less than those encountered in space, the fundamental coupled interaction of charged Gossamer structures with the ambient charge flux can be experimentally investigated. Of interest are, will the EIMS remain inflated during the charge deflections, and are there visible charge flux interactions. Aluminum coated Mylar membrane prototype structures are created to test their inflation capability using electrostatic charging. To simulate the charge flux, a 5keV electron emitter is utilized. The remaining charge flux at the end of the test chamber is measured with a Faraday cup mounted on a movable boom. A range of experiments with this electron emitter and detector were performed within a 30x60cm vacuum chamber with vacuum environment capability of 10-7 Torr. Experiments are performed with the charge flux aimed at the electrostatically inflated membrane structure (EIMS) in both charged and uncharged configurations. The amount of charge shielding behind and around the EIMS was studied for different combinations of membrane structure voltages and electron energies. Both passive and active shielding were observed, with active shielding capable of deflecting nearly all incoming electrons. The pattern of charge distribution around the structure was studied as well as the stability of the structures in the charge flow. The charge deflection experiments illustrate that the EIMS remain inflated during charge deflection, but will experience small amplitude oscillations. Investigations were performed to determine a potential cause of the vibrations. It is postulated these vibrations are due to the charge flux causing local membrane charge distribution changes. As the membrane structure inflation pressure is changed, the shape responds, and causes the observed sustained vibration. Having identified this phenomenon is important when considering electrostatically inflated membrane structures (EIMS) in a space environment. Additionally, this project included a study of membrane material impacts, specifically the impact of membrane thickness. Extremely thin materials presented new challenges with vacuum preparation techniques and rapid charging. The thinner and lighter membrane materials were successfully inflated using electrostatic forces in a vacuum chamber. However, care must be taken when varying the potentials of such lighter structures as the currents can cause local heating and melting of the very thin membranes. Lastly, a preliminary analysis is performed to study rough order of magnitude power requirements for using EIMS for radiation shielding. The EIMS power requirement becomes increasingly more challenging as the spacecraft voltage is increased. As a result, the emphasis is on the deflection of charges away from the spacecraft rather than totally stopping them. This significantly alleviates the initial power requirements. With modest technological development(s) active shielding is emerging to be a viable option.

Numerical analysis of ion wind flow using space charge for optimal design

NASA Astrophysics Data System (ADS)

Ko, Han Seo; Shin, Dong Ho; Baek, Soo Hong

2014-11-01

Ion wind flow has been widly studied for its advantages of a micro fluidic device. However, it is very difficult to predict the performance of the ion wind flow for various conditions because of its complicated electrohydrodynamic phenomena. Thus, a reliable numerical modeling is required to design an otimal ion wind generator and calculate velocity of the ion wind for the proper performance. In this study, the numerical modeling of the ion wind has been modified and newly defined to calculate the veloctiy of the ion wind flow by combining three basic models such as electrostatics, electrodynamics and fluid dynamics. The model has included presence of initial space charges to calculate transfer energy between space charges and air gas molecules using a developed space charge correlation. The simulation has been performed for a geometry of a pin to parallel plate electrode. Finally, the results of the simulation have been compared with the experimental data for the ion wind velocity to confirm the accuracy of the modified numerical modeling and to obtain the optimal design of the ion wind generator. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (No. 2013R1A2A2A01068653).

Summary Report of H- Injection Session II

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

Weiren Chou

1999-06-28

The H - injection was invented many years ago and has since been successfully applied in many machines over the last decades. The challenge to the high intensity machines is how to reduce the injection loss, which is usually the major part of total beam losses in a machine. Painting, both longitudinal and transverse, is an effective way to reduce the space charge e ects and to minimize losses. RF capture of a chopped beam also gives better e ciency than adiabatic capture. To employ a 2nd harmonic rf system to atten the rf bucket shape is another commonly usedmore » scheme. To compensate the capacitive space charge impedance by an inductive insert could be a new venture, but which is not discussed at the workshop due to time limitation. The foil physics is well understood. Simulations seem to be able to include all the important e ects in it, including the space charge. The general feeling is that we are in a good position concerning H - injection studies. Although there remains a number of design issues, the knowledge, experiences and tools in our hand should be able to address each of them properly.« less

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

Meusel, O., E-mail: o.meusel@iap.uni-frankfurt.de; Droba, M.; Noll, D.

The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree ofmore » space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed.« less

Development and Application of a Wireless Sensor for Space Charge Density Measurement in an Ultra-High-Voltage, Direct-Current Environment

PubMed Central

Xin, Encheng; Ju, Yong; Yuan, Haiwen

2016-01-01

A space charge density wireless measurement system based on the idea of distributed measurement is proposed for collecting and monitoring the space charge density in an ultra-high-voltage direct-current (UHVDC) environment. The proposed system architecture is composed of a number of wireless nodes connected with space charge density sensors and a base station. The space charge density sensor based on atmospheric ion counter method is elaborated and developed, and the ARM microprocessor and Zigbee radio frequency module are applied. The wireless network communication quality and the relationship between energy consumption and transmission distance in the complicated electromagnetic environment is tested. Based on the experimental results, the proposed measurement system demonstrates that it can adapt to the complex electromagnetic environment under the UHVDC transmission lines and can accurately measure the space charge density. PMID:27775627

Development and Application of a Wireless Sensor for Space Charge Density Measurement in an Ultra-High-Voltage, Direct-Current Environment.

PubMed

Xin, Encheng; Ju, Yong; Yuan, Haiwen

2016-10-20

A space charge density wireless measurement system based on the idea of distributed measurement is proposed for collecting and monitoring the space charge density in an ultra-high-voltage direct-current (UHVDC) environment. The proposed system architecture is composed of a number of wireless nodes connected with space charge density sensors and a base station. The space charge density sensor based on atmospheric ion counter method is elaborated and developed, and the ARM microprocessor and Zigbee radio frequency module are applied. The wireless network communication quality and the relationship between energy consumption and transmission distance in the complicated electromagnetic environment is tested. Based on the experimental results, the proposed measurement system demonstrates that it can adapt to the complex electromagnetic environment under the UHVDC transmission lines and can accurately measure the space charge density.

Massless spinning particle and null-string on AdS d : projective-space approach

NASA Astrophysics Data System (ADS)

Uvarov, D. V.

2018-07-01

The massless spinning particle and the tensionless string models on an AdS d background in the projective-space realization are proposed as constrained Hamiltonian systems. Various forms of particle and string Lagrangians are derived and classical mechanics is studied including the Lax-type representation of the equations of motion. After that, the transition to the quantum theory is discussed. The analysis of potential anomalies in the tensionless string model necessitates the introduction of ghosts and BRST charge. It is shown that a quantum BRST charge is nilpotent for any d if coordinate-momentum ordering for the phase-space bosonic variables, Weyl ordering for the fermions and cb () ordering for the ghosts is chosen, while conformal reparametrizations and space-time dilatations turn out to be anomalous for ordering in terms of positive and negative Fourier modes of the phase-space variables and ghosts.

ac aging and space-charge characteristics in low-density polyethylene polymeric insulation

NASA Astrophysics Data System (ADS)

Chen, G.; Fu, M.; Liu, X. Z.; Zhong, L. S.

2005-04-01

In the present work efforts have been made to investigate the influence of ac aging on space-charge dynamics in low-density polyethylene (LDPE). LDPE films with 200 μm were aged under various electric stress levels at 50 Hz for various times at ambient temperature. Space-charge dynamics in the samples after aging were monitored using the pulsed electroacoustic technique. It has been revealed that the space charge under ac aging conditions is related to the level of the applied field, duration of the voltage application, as well as the electrode materials. By comparing with the results of unaged sample the results from aged sample provide a direct evidence of changing trapping characteristics after ac aging. Negative space charge is present in the bulk of the material and the total amount of charge increases with the aging time. The amount of charge increases with the applied field. Charge decay test indicates that the charges are captured in deep traps. These deep traps are believed to form during the aging and related to change caused by injected charge. By using different electrode materials such as gold, brass alloy, and polyethylene loaded with carbon black, it was found that the electrode has an important role in the formation of charge, hence subsequent changes caused by charge. The charge dynamics of the aged samples under dc bias differ from the sample without ac aging, indicating changes brought in by ac aging. Chemical analysis by Fourier transform infrared spectroscope and Raman microscope reveals no detectable chemical changes taken place in the bulk of the material after ac aging. Finally, the consequence of the accumulation of space charge under ac conditions on the lifetime of the material has been discussed. The presence of deeply trapped space charge leads to an electric stress enhancement which may shorten the lifetime of the insulation system.

Electrically conducting polymers for aerospace applications

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Gaier, James R.; Good, Brian S.; Sharp, G. R.; Meador, Michael A.

1991-01-01

Current research on electrically conducting polymers from 1974 to the present is reviewed focusing on the development of materials for aeronautic and space applications. Problems discussed include extended pi-systems, pyrolytic polymers, charge-transfer systems, conductive matrix resins for composite materials, and prospects for the use of conducting polymers in space photovoltaics.

Electronic Combat in Space: Examining the Legality of Fielding a Space-Based Disruptive Electromagnetic Jamming System

DTIC Science & Technology

2007-06-15

particles ( asteroids and meteoroids), energetic charged particles (ions, protons, electrons, etc.), and electromagnetic and ionizing radiation (x-rays...These protocols include a ban on Non-Detectable Fragments; restrictions on the use of Mines , Booby Traps, and Other Devices; prohibitions on certain...

The Learning Space: Teachers Taking Charge.

ERIC Educational Resources Information Center

Steede-Terry, Karen

2001-01-01

Describes The Learning Space, a Seattle-based organization that provides support for classroom teachers by providing a means of communicating and collaborating with other teachers via the World Wide Web. Discusses the Web site that includes classroom lessons and considers growth of the organization to expand to other states. (LRW)

Bulk charging and breakdown in electron-irradiated polymers

NASA Technical Reports Server (NTRS)

Frederickson, A. R.

1981-01-01

High energy electron irradiations were performed in an experimental and theoretical study of ten common polymers. Breakdowns were monitored by measuring currents between the electrodes on each side of the planar samples. Sample currents as a function of time during irradiation are compared with theory. Breakdowns are correlated with space charge electric field strength and polarity. Major findings include evidence that all polymers tested broke down, breakdowns remove negligible bulk charge and no breakdowns are seen below 20 million V/m.

Analysis of Spacecraft Charging, Particle Beams and Geophysical Data Bases.

DTIC Science & Technology

1983-07-31

READINSTRUCTIONSBEFORE COMPLETING FORM I. REPORT NUMDER 2. DOVT ACCrSS 0 2. P3ECIP’FNT’S CAT ALOG NUMU I I 4. TITLE (and Subtitle) S. TYrE OF REPORT a...include solar , magnetic field, substorm and space charge effects. Charging dynamics can exist due to varying photoemission over a rotating or eclipsing...examined. The most recent SCATHA simulations have implemented time dependent specification of the plasma environment and of solar flux. 12’ 1.1

Simulation of the Interaction Between Flywheel Energy Storage and Battery Energy Storage on the International Space Station

NASA Technical Reports Server (NTRS)

Trouong, Long V.; Wolff, Frederic J.; Dravid, Narayan V.; Li, Ponlee

2000-01-01

Replacement of one module of the battery charge discharge unit (BCDU) of the International Space Station (ISS) by a flywheel energy storage unit (FESU) is under consideration. Integration of these two dissimilar systems is likely to surface difficulties in areas of system stability and fault protection. Other issues that need to be addressed include flywheel charge and discharge profiles and their effect on the ISS power system as well as filter sizing for power Ability purposes. This paper describes a SABER based simulation to study these issues.

Space Science at Los Alamos National Laboratory

NASA Astrophysics Data System (ADS)

Smith, Karl

2017-09-01

The Space Science and Applications group (ISR-1) in the Intelligence and Space Research (ISR) division at the Los Alamos National Laboratory lead a number of space science missions for civilian and defense-related programs. In support of these missions the group develops sensors capable of detecting nuclear emissions and measuring radiations in space including γ-ray, X-ray, charged-particle, and neutron detection. The group is involved in a number of stages of the lifetime of these sensors including mission concept and design, simulation and modeling, calibration, and data analysis. These missions support monitoring of the atmosphere and near-Earth space environment for nuclear detonations as well as monitoring of the local space environment including space-weather type events. Expertise in this area has been established over a long history of involvement with cutting-edge projects continuing back to the first space based monitoring mission Project Vela. The group's interests cut across a large range of topics including non-proliferation, space situational awareness, nuclear physics, material science, space physics, astrophysics, and planetary physics.

Analysis of a rotating advanced-technology space station for the year 2025

NASA Technical Reports Server (NTRS)

Queijo, M. J.; Butterfield, A. J.; Cuddihy, W. F.; King, C. B.; Stone, R. W.; Garn, P. A.

1988-01-01

An analysis is made of several aspects of an advanced-technology rotating space station configuration generated under a previous study. The analysis includes examination of several modifications of the configuration, interface with proposed launch systems, effects of low-gravity environment on human subjects, and the space station assembly sequence. Consideration was given also to some aspects of space station rotational dynamics, surface charging, and the possible application of tethers.

Chemical Physics of Charge Mechanisms in Nonmetallic Spacecraft Materials.

DTIC Science & Technology

1979-05-01

techniques may not provide data truly representative of actual in-orbit space - craft charging effects . The results of the discharge characterization...phenomena, commonly referred to collectively as space - !. craft charging effects , can produce undesirable and sometimes serious prob- lems with the...lifetime of future space systems requires a practical understanding of spacecraft charging phenomena and their effects . The laboratory program

Effect of Fe{sub 3}O{sub 4} nanoparticles on space charge distribution in propylene carbonate under impulse voltage

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

Sima, Wenxia, E-mail: cqsmwx@cqu.edu.cn; Song, He; Yang, Qing

2015-12-15

Addition of nanoparticles of the ferromagnetic material Fe{sub 3}O{sub 4} can increase the positive impulse breakdown voltage of propylene carbonate by 11.65%. To further investigate the effect of ferromagnetic nanoparticles on the space charge distribution in the discharge process, the present work set up a Kerr electro-optic field mapping measurement system using an array photodetector to carry out time-continuous measurement of the electric field and space charge distribution in propylene carbonate before and after modification. Test results show that fast electrons can be captured by Fe{sub 3}O{sub 4} nanoparticles and converted into relatively slow, negatively charged particles, inhibiting the generationmore » and transportation of the space charge, especially the negative space charge.« less

Electro-chemical sensors, sensor arrays and circuits

DOEpatents

Katz, Howard E.; Kong, Hoyoul

2014-07-08

An electro-chemical sensor includes a first electrode, a second electrode spaced apart from the first electrode, and a semiconductor channel in electrical contact with the first and second electrodes. The semiconductor channel includes a trapping material. The trapping material reduces an ability of the semiconductor channel to conduct a current of charge carriers by trapping at least some of the charge carriers to localized regions within the semiconductor channel. The semiconductor channel includes at least a portion configured to be exposed to an analyte to be detected, and the trapping material, when exposed to the analyte, interacts with the analyte so as to at least partially restore the ability of the semiconductor channel to conduct the current of charge carriers.

Experimental evidence of space charge driven resonances in high intensity linear accelerators

DOE PAGES

Jeon, Dong -O

2016-01-12

In the construction of high intensity accelerators, it is the utmost goal to minimize the beam loss by avoiding or minimizing contributions of various halo formation mechanisms. As a halo formation mechanism, space charge driven resonances are well known for circular accelerators. However, the recent finding showed that even in linear accelerators the space charge potential can excite the 4σ = 360° fourth order resonance [D. Jeon et al., Phys. Rev. ST Accel. Beams 12, 054204 (2009)]. This study increased the interests in space charge driven resonances of linear accelerators. Experimental studies of the space charge driven resonances of highmore » intensity linear accelerators are rare as opposed to the multitude of simulation studies. This paper presents an experimental evidence of the space charge driven 4σ ¼ 360° resonance and the 2σ x(y) – 2σ z = 0 resonance of a high intensity linear accelerator through beam profile measurements from multiple wire-scanners. Moreover, measured beam profiles agree well with the characteristics of the space charge driven 4σ = 360° resonance and the 2σ x(y) – 2σ z = 0 resonance that are predicted by the simulation.« less

Midcourse Space Experiment (MSX)

DTIC Science & Technology

1992-08-01

Facility (PCF), on South Base. The PPF houses the MSX spacecraft for the prelaunch operations (installation of payload fairing, battery charging , etc...include: unpacking the spacecraft from its shipping container; charging the onboard nickel-hydrogen batteries ; filling the cryostat with solid...activities, and will remain in orbit for several hundred years. The MSX spacecraft is solar powered with a battery backup. The battery is capable of

Longitudinal space charge compensation at PSR

NASA Astrophysics Data System (ADS)

Neri, Filippo

1998-11-01

The longitudinal space-charge force in neutron spallation source compressor ring or other high intensity proton storage rings can be compensated by introducing an insert in the ring. The effect of the inductor is to cancel all or part of the space charge potential, because it is capacitive. The Proton Storage Ring at Los Alamos National Laboratory is a compressor ring used to produce short pulses of spallation neutrons. Inductive inserts design for space charge compensation at the Los Alamos Proton Storage Ring is described.

The differential algebra based multiple level fast multipole algorithm for 3D space charge field calculation and photoemission simulation

DOE PAGES

None, None

2015-09-28

Coulomb interaction between charged particles inside a bunch is one of the most importance collective effects in beam dynamics, becoming even more significant as the energy of the particle beam is lowered to accommodate analytical and low-Z material imaging purposes such as in the time resolved Ultrafast Electron Microscope (UEM) development currently underway at Michigan State University. In addition, space charge effects are the key limiting factor in the development of ultrafast atomic resolution electron imaging and diffraction technologies and are also correlated with an irreversible growth in rms beam emittance due to fluctuating components of the nonlinear electron dynamics.more » In the short pulse regime used in the UEM, space charge effects also lead to virtual cathode formation in which the negative charge of the electrons emitted at earlier times, combined with the attractive surface field, hinders further emission of particles and causes a degradation of the pulse properties. Space charge and virtual cathode effects and their remediation are core issues for the development of the next generation of high-brightness UEMs. Since the analytical models are only applicable for special cases, numerical simulations, in addition to experiments, are usually necessary to accurately understand the space charge effect. In this paper we will introduce a grid-free differential algebra based multiple level fast multipole algorithm, which calculates the 3D space charge field for n charged particles in arbitrary distribution with an efficiency of O(n), and the implementation of the algorithm to a simulation code for space charge dominated photoemission processes.« less

Analysis of space charge fields using the Lienard-Wiechert potential and the method of images during the photoemission of the electron beam from the cathode

NASA Astrophysics Data System (ADS)

Salah, Wa'el

2017-01-01

We present a numerical analysis of the space charge effect and the effect of image charge force on the cathode surface for a laser-driven RF-photocathode gun. In this numerical analysis, in the vicinity of the cathode surface, we used an analytical method based on Lienard-Weichert retarded potentials. The analytical method allows us to calculate longitudinal and radial electric fields, and the azimuth magnetic field due to both space charge effect and the effect of the image charge force. We calculate the electro-magnetic fields in the following two conditions for the "ELSA" photoinjector. The first condition is in the progress of photoemission, which corresponds to the inside of the emitted beam, and the second condition is at the end of the photoemission. The electromagnetic fields due to the space charge effect and the effect of the image charge force, and the sum of them, which corresponds to the global electro-magnetic fields, are shown. Based on these numerical results, we discussed the effects of the space charge and the image charge in the immediate vicinity of the cathode.

Experimental Evidence for Space-Charge Effects between Ions of the Same Mass-to-Charge in Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry

PubMed Central

Wong, Richard L.; Amster, I. Jonathan

2009-01-01

It is often stated that ions of the same mass-to-charge do not induce space-charge frequency shifts among themselves in an ion cyclotron resonance mass spectrometry measurement. Here, we demonstrate space-charge induced frequency shifts for ions of a single mass-to-charge. The monoisotopic atomic ion, Cs+, was used for this study. The measured frequency is observed to decrease linearly with an increase in the number of ions, as has been reported previously for space-charge effects between ions of different mass-to-charge. The frequency shift between ions of the same m/z value are compared to that induced between ions of different m/z value, and is found to be 7.5 times smaller. Control experiments were performed to ensure that the observed space-charge effects are not artifacts of the measurement or of experimental design. The results can be rationalized by recognizing that the electric forces between ions in a magnetic field conform to the weak form of the Newton's third law, where the action and reaction forces do not cancel exactly. PMID:19562102

Effects of Space Weather on Geosynchronous Electromagnetic Spacecraft Perturbations Using Statistical Fluxes

NASA Astrophysics Data System (ADS)

Hughes, J.; Schaub, H.

2017-12-01

Spacecraft can charge to very negative voltages at GEO due to interactions with the space plasma. This can cause arcing which can damage spacecraft electronics or solar panels. Recently, it has been suggested that spacecraft charging may lead to orbital perturbations which change the orbits of lightweight uncontrolled debris orbits significantly. The motions of High Area to Mass Ratio objects are not well explained with just perturbations from Solar Radiation Pressure (SRP) and earth, moon, and sun gravity. A charged spacecraft will experience a Lorentz force as the spacecraft moves relative to Earth's magnetic field, as well as a Lorentz torque and eddy current torques if the object is rotating. Prior work assuming a constant "worst case" voltage has shown that Lorentz and eddy torques can cause quite large orbital changes by rotating the object to experience more or less SRP. For some objects, including or neglecting these electromagnetic torques can lead to differences of thousands of kilometers after only two orbits. This paper will further investigate the effects of electromagnetic perturbations by using a charging model that uses measured flux distributions to better simulate natural charging. This differs from prior work which used a constant voltage or Maxwellian distributions. This is done to a calm space weather case of Kp = 2 and a stormy case where Kp = 8. Preliminary analysis suggests that electrostatics will still cause large orbital changes even with the more realistic charging model.

100 years of the physics of diodes

NASA Astrophysics Data System (ADS)

Zhang, Peng; Valfells, Ágúst; Ang, L. K.; Luginsland, J. W.; Lau, Y. Y.

2017-03-01

The Child-Langmuir Law (CL), discovered a century ago, gives the maximum current that can be transported across a planar diode in the steady state. As a quintessential example of the impact of space charge shielding near a charged surface, it is central to the studies of high current diodes, such as high power microwave sources, vacuum microelectronics, electron and ion sources, and high current drivers used in high energy density physics experiments. CL remains a touchstone of fundamental sheath physics, including contemporary studies of nanoscale quantum diodes and nano gap based plasmonic devices. Its solid state analog is the Mott-Gurney law, governing the maximum charge injection in solids, such as organic materials and other dielectrics, which is important to energy devices, such as solar cells and light emitting diodes. This paper reviews the important advances in the physics of diodes since the discovery of CL, including virtual cathode formation and extension of CL to multiple dimensions, to the quantum regime, and to ultrafast processes. We review the influence of magnetic fields, multiple species in bipolar flow, electromagnetic and time dependent effects in both short pulse and high frequency THz limits, and single electron regimes. Transitions from various emission mechanisms (thermionic-, field-, and photoemission) to the space charge limited state (CL) will be addressed, especially highlighting the important simulation and experimental developments in selected contemporary areas of study. We stress the fundamental physical links between the physics of beams to limiting currents in other areas, such as low temperature plasmas, laser plasmas, and space propulsion.

Simulation of Space Charge Dynamic in Polyethylene Under DC Continuous Electrical Stress

NASA Astrophysics Data System (ADS)

Boukhari, Hamed; Rogti, Fatiha

2016-10-01

The space charge dynamic plays a very important role in the aging and breakdown of polymeric insulation materials under high voltage. This is due to the intensification of the local electric field and the attendant chemical-mechanical effects in the vicinity around the trapped charge. In this paper, we have investigated the space charge dynamic in low-density polyethylene under high direct-current voltage, which is evaluated by experimental conditions. The evaluation is on the basis of simulation using a bipolar charge transport model consisting of charge injection, transports, trapping, detrapping, and recombination phenomena. The theoretical formulation of the physical problem is based on the Poisson, the continuity, and the transport equations. Numerical results provide temporal and local distributions of the electric field, the space charge density for the different kinds of charges (net charge density, mobile and trapped of electron density, mobile hole density), conduction and displacement current densities, and the external current. The result shows the appearance of the negative packet-like space charge with a large amount of the bulk under the dc electric field of 100 kV/mm, and the induced distortion of the electric field is largely near to the anode, about 39% higher than the initial electric field applied.

Studies of beam plasma interactions in a space simulation chamber using prototype Space Shuttle instruments

NASA Technical Reports Server (NTRS)

Banks, P. M.; Raitt, W. J.; Denig, W. F.

1982-01-01

In March, 1981, electron beam experiments were conducted in a large space simulation chamber using equipment destined to be flown aboard NASA's Office of Space Science-1 pallet (OSS-1). Two major flight experiments were involved. They include the Vehicle Charging and Potential (VCAP) experiment and the Plasma Diagnostics Package (PDP). Apparatus connected with VCAP included a Fast Pulse Electron Gun (FPEG), and a Charge and Current Probe (CCP). A preliminary view is provided of the results obtained when the electron emissions were held steady over relatively long periods of time such that steady state conditions could be obtained with respect to the electron beam interaction with the neutral gases and plasma of the vacuum chamber. Of particular interest was the plasma instability feature known as the Beam Plasma Discharge. For the present experiments the FPEG was used in a dc mode with a range of currents of 2 to 80 mA at a beam energy of 970 eV. Attention is given to the emissions of VLF and HF noise associated with the dc beam.

Detection of electromagnetic radiation using nonlinear materials

DOEpatents

Hwang, Harold Y.; Liu, Mengkun; Averitt, Richard D.; Nelson, Keith A.; Sternbach, Aaron; Fan, Kebin

2016-06-14

An apparatus for detecting electromagnetic radiation within a target frequency range is provided. The apparatus includes a substrate and one or more resonator structures disposed on the substrate. The substrate can be a dielectric or semiconductor material. Each of the one or more resonator structures has at least one dimension that is less than the wavelength of target electromagnetic radiation within the target frequency range, and each of the resonator structures includes at least two conductive structures separated by a spacing. Charge carriers are induced in the substrate near the spacing when the resonator structures are exposed to the target electromagnetic radiation. A measure of the change in conductivity of the substrate due to the induced charge carriers provides an indication of the presence of the target electromagnetic radiation.

Space charge dosimeters for extremely low power measurements of radiation in shipping containers

DOEpatents

Britton, Jr., Charles L.; Buckner, Mark A [Oak Ridge, TN; Hanson, Gregory R [Clinton, TN; Bryan, William L [Knoxville, TN

2011-05-03

Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

Space charge dosimeters for extremely low power measurements of radiation in shipping containers

DOEpatents

Britton, Jr; Charles, L [Alcoa, TN; Buckner, Mark A [Oak Ridge, TN; Hanson, Gregory R [Clinton, TN; Bryan, William L [Knoxville, TN

2011-04-26

Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes in situ polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

NASA Astrophysics Data System (ADS)

Hanquist, Kyle M.; Hara, Kentaro; Boyd, Iain D.

2017-02-01

Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.

14 CFR 1215.113 - User charges.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false User charges. 1215.113 Section 1215.113 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA RELAY SATELLITE SYSTEM (TDRSS) Use and Reimbursement Policy for Non-U.S. Government Users § 1215.113 User charges. (a) The user...

14 CFR 1215.113 - User charges.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true User charges. 1215.113 Section 1215.113 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA RELAY SATELLITE SYSTEM (TDRSS) Use and Reimbursement Policy for Non-U.S. Government Users § 1215.113 User charges. (a) The user...

14 CFR § 1215.113 - User charges.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false User charges. § 1215.113 Section § 1215.113 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA RELAY.... (a) The user shall reimburse NASA the sum of the charges for standard and mission-unique services...

41 CFR 102-85.145 - When are customer agencies responsible for Rent charges?

Code of Federal Regulations, 2010 CFR

2010-07-01

...; or (2) All other space: Either GSA's space charges for 4 months plus the cost of tenant improvements or GSA's actual costs, whichever is less. ... PROPERTY 85-PRICING POLICY FOR OCCUPANCY IN GSA SPACE Rent Charges § 102-85.145 When are customer agencies...

Space-charge-mediated anomalous ferroelectric switching in P(VDF-TrEE) polymer films.

PubMed

Hu, Weijin; Wang, Zhihong; Du, Yuanmin; Zhang, Xi-Xiang; Wu, Tom

2014-11-12

We report on the switching dynamics of P(VDF-TrEE) copolymer devices and the realization of additional substable ferroelectric states via modulation of the coupling between polarizations and space charges. The space-charge-limited current is revealed to be the dominant leakage mechanism in such organic ferroelectric devices, and electrostatic interactions due to space charges lead to the emergence of anomalous ferroelectric loops. The reliable control of ferroelectric switching in P(VDF-TrEE) copolymers opens doors toward engineering advanced organic memories with tailored switching characteristics.

Space charge effects on the third order coupled resonance

NASA Astrophysics Data System (ADS)

Franchetti, Giuliano; Gilardoni, Simone; Huschauer, Alexander; Schmidt, Frank; Wasef, Raymond

2017-08-01

The effect of space charge on bunched beams has been the subject of numerous numerical and experimental studies in the first decade of 2000. Experimental campaigns performed at the CERN Proton Synchrotron in 2002 and at the GSI SIS18 in 2008 confirmed the existence of an underlying mechanism in the beam dynamics of periodic resonance crossing induced by the synchrotron motion and space charge. In this article we present an extension of the previous studies to describe the effect of space charge on a controlled coupled (2D) third order resonance. The experimental and simulation results of this latest campaign shed a new light on the difficulties of the 2D particle dynamics. We find striking experimental evidence that space charge and the coupled resonance create an unusual coupling in the phase space, leading to the formation of an asymmetric halo. Moreover, this study demonstrates a clear link between halo formation and fixed-lines.

Validation of ISS Floating Potential Measurement Unit Electron Densities and Temperatures

NASA Technical Reports Server (NTRS)

Coffey, Victoria N.; Minow, Joseph I.; Parker, Linda N.; Bui, Them; Wright, Kenneth, Jr.; Koontz, Steven L.; Schneider, T.; Vaughn, J.; Craven, P.

2007-01-01

Validation of the Floating Potential Measurement Unit (FPMU) electron density and temperature measurements is an important step in the process of evaluating International Space Station spacecraft charging issues .including vehicle arcing and hazards to crew during extravehicular activities. The highest potentials observed on Space Station are due to the combined VxB effects on a large spacecraft and the collection of ionospheric electron and ion currents by the 160 V US solar array modules. Ionospheric electron environments are needed for input to the ISS spacecraft charging models used to predict the severity and frequency of occurrence of ISS charging hazards. Validation of these charging models requires comparing their predictions with measured FPMU values. Of course, the FPMU measurements themselves must also be validated independently for use in manned flight safety work. This presentation compares electron density and temperatures derived from the FPMU Langmuir probes and Plasma Impedance Probe against the independent density and temperature measurements from ultraviolet imagers, ground based incoherent scatter radar, and ionosonde sites.

Radiation and Plasma Environments for Lunar Missions

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Edwards, David L.; Altstatt, Richard L.; Diekmann, Anne M.; Blackwell, William C., Jr.; Harine, Katherine J.

2006-01-01

Space system design for lunar orbit and extended operations on the lunar surface requires analysis of potential system vulnerabilities to plasma and radiation environments to minimize anomalies and assure that environmental failures do not occur during the mission. Individual environments include the trapped particles in Earth s radiation belts, solar energetic particles and galactic cosmic rays, plasma environments encountered in transit to the moon and on the lunar surface (solar wind, terrestrial magnetosheath and magnetotail, and lunar photoelectrons), and solar ultraviolet and extreme ultraviolet photons. These are the plasma and radiation environments which contribute to a variety of effects on space systems including total ionizing dose and dose rate effects in electronics, degradation of materials in the space environment, and charging of spacecraft and lunar dust. This paper provides a survey of the relevant charged particle and photon environments of importance to lunar mission design ranging from the lowest (approx.few 10 s eV) photoelectron energies to the highest (approx.GeV) cosmic ray energies.

Modeling Electrostatic Fields Generated by Internal Charging of Materials in Space Radiation Environments

NASA Technical Reports Server (NTRS)

Minow, Joseph I.

2011-01-01

Internal charging is a risk to spacecraft in energetic electron environments. DICTAT, NU MIT computational codes are the most widely used engineering tools for evaluating internal charging of insulator materials exposed to these environments. Engineering tools are designed for rapid evaluation of ESD threats, but there is a need for more physics based models for investigating the science of materials interactions with energetic electron environments. Current tools are limited by the physics included in the models and ease of user implementation .... additional development work is needed to improve models.

Strange Quark Magnetic Moment of the Nucleon at the Physical Point.

PubMed

Sufian, Raza Sabbir; Yang, Yi-Bo; Alexandru, Andrei; Draper, Terrence; Liang, Jian; Liu, Keh-Fei

2017-01-27

We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the physical pion mass. We perform a model-independent extraction of the strange magnetic moment and the strange charge radius from the electromagnetic form factors in the momentum transfer range of 0.051  GeV^{2}≲Q^{2}≲1.31  GeV^{2}. The finite lattice spacing and finite volume corrections are included in a global fit with 24 valence quark masses on four lattices with different lattice spacings, different volumes, and four sea quark masses including one at the physical pion mass. We obtain the strange magnetic moment G_{M}^{s}(0)=-0.064(14)(09)μ_{N}. The four-sigma precision in statistics is achieved partly due to low-mode averaging of the quark loop and low-mode substitution to improve the statistics of the nucleon propagator. We also obtain the strange charge radius ⟨r_{s}^{2}⟩_{E}=-0.0043(16)(14)  fm^{2}.

Vacuum Flashover Characteristics of Laminated Polystyrene Insulators

DTIC Science & Technology

1999-06-01

space charge dominated. A minimum wafer thickness and/or the number of wafers required for the application can be calculated. Equation 1 represents...toward the anode. qn is the fraction of charge deposited on that section of the stack. Equation 1 comes from the assumption that a space charge ...Rodriguez, A.E., and Honig, E.M., "Characterization of an Insulated Space Charge Limited Non-Relativistic Electron Beam Diode Operating at 300 kV/cm

Space-charge limited photocurrent.

PubMed

Mihailetchi, V D; Wildeman, J; Blom, P W M

2005-04-01

In 1971 Goodman and Rose predicted the occurrence of a fundamental electrostatic limit for the photocurrent in semiconductors at high light intensities. Blends of conjugated polymers and fullerenes are an ideal model system to observe this space-charge limit experimentally, since they combine an unbalanced charge transport, long lifetimes, high charge carrier generation efficiencies, and low mobility of the slowest charge carrier. The experimental photocurrents reveal all the characteristics of a space-charge limited photocurrent: a one-half power dependence on voltage, a three-quarter power dependence on light intensity, and a one-half power scaling of the voltage at which the photocurrent switches into full saturation with light intensity.

Structure, stability, and thermodynamics of lamellar DNA-lipid complexes.

PubMed Central

Harries, D; May, S; Gelbart, W M; Ben-Shaul, A

1998-01-01

We develop a statistical thermodynamic model for the phase evolution of DNA-cationic lipid complexes in aqueous solution, as a function of the ratios of charged to neutral lipid and charged lipid to DNA. The complexes consist of parallel strands of DNA intercalated in the water layers of lamellar stacks of mixed lipid bilayers, as determined by recent synchrotron x-ray measurements. Elastic deformations of the DNA and the lipid bilayers are neglected, but DNA-induced spatial inhomogeneities in the bilayer charge densities are included. The relevant nonlinear Poisson-Boltzmann equation is solved numerically, including self-consistent treatment of the boundary conditions at the polarized membrane surfaces. For a wide range of lipid compositions, the phase evolution is characterized by three regions of lipid to DNA charge ratio, rho: 1) for low rho, the complexes coexist with excess DNA, and the DNA-DNA spacing in the complex, d, is constant; 2) for intermediate rho, including the isoelectric point rho = 1, all of the lipid and DNA in solution is incorporated into the complex, whose inter-DNA distance d increases linearly with rho; and 3) for high rho, the complexes coexist with excess liposomes (whose lipid composition is different from that in the complex), and their spacing d is nearly, but not completely, independent of rho. These results can be understood in terms of a simple charging model that reflects the competition between counterion entropy and inter-DNA (rho < 1) and interbilayer (rho > 1) repulsions. Finally, our approach and conclusions are compared with theoretical work by others, and with relevant experiments. PMID:9649376

Dependence of the TMCI Threshold on the Space Charge Tune Shift

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

Balbekov, V.

2016-07-20

Transverse mode coupling instability of a bunch with space charge is considered in frameworks of the boxcar model. Presented results demonstrate a monotonous growth of the TMCI threshold at increasing space charge tune shift, and do not support the supposition that the monotony can be violated at a higher SC.

Causal electric charge diffusion and balance functions in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Kapusta, Joseph I.; Plumberg, Christopher

2018-01-01

We study the propagation and diffusion of electric charge fluctuations in high-energy heavy-ion collisions using the Cattaneo form for the dissipative part of the electric current. As opposed to the ordinary diffusion equation this form limits the speed at which charge can propagate. Including the noise term in the current, which arises uniquely from the fluctuation-dissipation theorem, we calculate the balance functions for charged hadrons in a simple 1+1-dimensional Bjorken hydrodynamical model. Limiting the speed of propagation of charge fluctuations increases the height and reduces the width of these balance functions when plotted versus rapidity. We also estimate the numerical value of the associated diffusion time constant from anti-de Sitter-space/conformal-field theory.

Methods of treating complex space vehicle geometry for charged particle radiation transport

NASA Technical Reports Server (NTRS)

Hill, C. W.

1973-01-01

Current methods of treating complex geometry models for space radiation transport calculations are reviewed. The geometric techniques used in three computer codes are outlined. Evaluations of geometric capability and speed are provided for these codes. Although no code development work is included several suggestions for significantly improving complex geometry codes are offered.

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

None, None

Coulomb interaction between charged particles inside a bunch is one of the most importance collective effects in beam dynamics, becoming even more significant as the energy of the particle beam is lowered to accommodate analytical and low-Z material imaging purposes such as in the time resolved Ultrafast Electron Microscope (UEM) development currently underway at Michigan State University. In addition, space charge effects are the key limiting factor in the development of ultrafast atomic resolution electron imaging and diffraction technologies and are also correlated with an irreversible growth in rms beam emittance due to fluctuating components of the nonlinear electron dynamics.more » In the short pulse regime used in the UEM, space charge effects also lead to virtual cathode formation in which the negative charge of the electrons emitted at earlier times, combined with the attractive surface field, hinders further emission of particles and causes a degradation of the pulse properties. Space charge and virtual cathode effects and their remediation are core issues for the development of the next generation of high-brightness UEMs. Since the analytical models are only applicable for special cases, numerical simulations, in addition to experiments, are usually necessary to accurately understand the space charge effect. In this paper we will introduce a grid-free differential algebra based multiple level fast multipole algorithm, which calculates the 3D space charge field for n charged particles in arbitrary distribution with an efficiency of O(n), and the implementation of the algorithm to a simulation code for space charge dominated photoemission processes.« less

Charged particle and magnetic field research in space

NASA Technical Reports Server (NTRS)

1972-01-01

Research completed and in progress is described, related publications and reports are listed, and abstracts of papers and talks on results of the research are given. The charged particle research centered on OGO-5 and OGO-6 electron spectrometer data, and theoretical radiation belt studies. Work on the ATS-1 magnetometer project included development of production data reduction programs, development of spectral analysis procedures, and scientific studies of ULF waves at synchronous orbit. The magnetic fields research also included work on the Mariner project and theoretical studies on the solar wind.

Space Environment Testing of Photovoltaic Array Systems at NASA's Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Phillips, Brandon S.; Schneider, Todd A.; Vaughn, Jason A.; Wright, Kenneth H., Jr.

2015-01-01

To successfully operate a photovoltaic (PV) array system in space requires planning and testing to account for the effects of the space environment. It is critical to understand space environment interactions not only on the PV components, but also the array substrate materials, wiring harnesses, connectors, and protection circuitry (e.g. blocking diodes). Key elements of the space environment which must be accounted for in a PV system design include: Solar Photon Radiation, Charged Particle Radiation, Plasma, and Thermal Cycling. While solar photon radiation is central to generating power in PV systems, the complete spectrum includes short wavelength ultraviolet components, which photo-ionize materials, as well as long wavelength infrared which heat materials. High energy electron radiation has been demonstrated to significantly reduce the output power of III-V type PV cells; and proton radiation damages material surfaces - often impacting coverglasses and antireflective coatings. Plasma environments influence electrostatic charging of PV array materials, and must be understood to ensure that long duration arcs do not form and potentially destroy PV cells. Thermal cycling impacts all components on a PV array by inducing stresses due to thermal expansion and contraction. Given such demanding environments, and the complexity of structures and materials that form a PV array system, mission success can only be ensured through realistic testing in the laboratory. NASA's Marshall Space Flight Center has developed a broad space environment test capability to allow PV array designers and manufacturers to verify their system's integrity and avoid costly on-orbit failures. The Marshall Space Flight Center test capabilities are available to government, commercial, and university customers. Test solutions are tailored to meet the customer's needs, and can include performance assessments, such as flash testing in the case of PV cells.

Space Environmental Effects Testing Capability at the Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

DeWittBurns, H.; Craven, Paul; Finckenor, Miria; Nehls, Mary; Schneider, Todd; Vaughn, Jason

2012-01-01

Understanding the effects of the space environment on materials and systems is fundamental and essential for mission success. If not properly understood and designed for, the effects of the environment can lead to degradation of materials, reduction of functional lifetime, and system failure. In response to this need, the Marshall Space Flight Center has developed world class Space Environmental Effects (SEE) expertise and test facilities to simulate the space environment. Capabilities include multiple unique test systems comprising the most complete SEE testing capability available. These test capabilities include charged particle radiation (electrons, protons, ions), ultraviolet radiation (UV), vacuum ultraviolet radiation (VUV), atomic oxygen, plasma effects, space craft charging, lunar surface and planetary effects, vacuum effects, and hypervelocity impacts as well as the combination of these capabilities. In addition to the uniqueness of the individual test capabilities, MSFC is the only NASA facility where the effects of the different space environments can be tested in one location. Combined with additional analytical capabilities for pre- and post-test evaluation, MSFC is a one-stop shop for materials testing and analysis. The SEE testing and analysis are performed by a team of award winning experts nationally recognized for their contributions in the study of the effects of the space environment on materials and systems. With this broad expertise in space environmental effects and the variety of test systems and equipment available, MSFC is able to customize tests with a demonstrated ability to rapidly adapt and reconfigure systems to meet customers needs. Extensive flight experiment experience bolsters this simulation and analysis capability with a comprehensive understanding of space environmental effects.

Simulation of a cascaded longitudinal space charge amplifier for coherent radiation generation

DOE PAGES

Halavanau, A.; Piot, P.

2016-03-03

Longitudinal space charge (LSC) effects are generally considered as harmful in free-electron lasers as they can seed unfavorable energy modulations that can result in density modulations with associated emittance dilution. It was pointed out, however, that such \\micro-bunching instabilities" could be potentially useful to support the generation of broadband coherent radiation. Therefore there has been an increasing interest in devising accelerator beam lines capable of controlling LSC induced density modulations. In the present paper we augment these previous investigations by combining a grid-less space charge algorithm with the popular particle-tracking program elegant. This high-fidelity model of the space charge ismore » used to benchmark conventional LSC models. We then employ the developed model to optimize the performance of a cascaded longitudinal space charge amplifier using beam parameters comparable to the ones achievable at Fermilab Accelerator Science & Technology (FAST) facility currently under commissioning at Fermilab.« less

Ultra-low current beams in UMER to model space-charge effects in high-energy proton and ion machines

NASA Astrophysics Data System (ADS)

Bernal, S.; Beaudoin, B.; Baumgartner, H.; Ehrenstein, S.; Haber, I.; Koeth, T.; Montgomery, E.; Ruisard, K.; Sutter, D.; Yun, D.; Kishek, R. A.

2017-03-01

The University of Maryland Electron Ring (UMER) has operated traditionally in the regime of strong space-charge dominated beam transport, but small-current beams are desirable to significantly reduce the direct (incoherent) space-charge tune shift as well as the tune depression. This regime is of interest to model space-charge effects in large proton and ion rings similar to those used in nuclear physics and spallation neutron sources, and also for nonlinear dynamics studies of lattices inspired on the Integrable Optics Test Accelerator (IOTA). We review the definitions of beam vs. space-charge intensities and discuss three methods for producing very small beam currents in UMER. We aim at generating 60µA - 1.0mA, 100 ns, 10 keV beams with normalized rms emittances of the order of 0.1 - 1.0µm.

WSN-Based Space Charge Density Measurement System

PubMed Central

Deng, Dawei; Yuan, Haiwen; Lv, Jianxun; Ju, Yong

2017-01-01

It is generally acknowledged that high voltage direct current (HVDC) transmission line endures the drawback of large area, because of which the utilization of cable for space charge density monitoring system is of inconvenience. Compared with the traditional communication network, wireless sensor network (WSN) shows advantages in small volume, high flexibility and strong self-organization, thereby presenting great potential in solving the problem. Additionally, WSN is more suitable for the construction of distributed space charge density monitoring system as it has longer distance and higher mobility. A distributed wireless system is designed for collecting and monitoring the space charge density under HVDC transmission lines, which has been widely applied in both Chinese state grid HVDC test base and power transmission projects. Experimental results of the measuring system demonstrated its adaptability in the complex electromagnetic environment under the transmission lines and the ability in realizing accurate, flexible, and stable demands for the measurement of space charge density. PMID:28052105

WSN-Based Space Charge Density Measurement System.

PubMed

Deng, Dawei; Yuan, Haiwen; Lv, Jianxun; Ju, Yong

2017-01-01

It is generally acknowledged that high voltage direct current (HVDC) transmission line endures the drawback of large area, because of which the utilization of cable for space charge density monitoring system is of inconvenience. Compared with the traditional communication network, wireless sensor network (WSN) shows advantages in small volume, high flexibility and strong self-organization, thereby presenting great potential in solving the problem. Additionally, WSN is more suitable for the construction of distributed space charge density monitoring system as it has longer distance and higher mobility. A distributed wireless system is designed for collecting and monitoring the space charge density under HVDC transmission lines, which has been widely applied in both Chinese state grid HVDC test base and power transmission projects. Experimental results of the measuring system demonstrated its adaptability in the complex electromagnetic environment under the transmission lines and the ability in realizing accurate, flexible, and stable demands for the measurement of space charge density.

Bulk Charging of Dielectrics in Cryogenic Space Environments

NASA Technical Reports Server (NTRS)

Minow, J. I.; Coffey, V. N.; Blackwell, W. C., Jr.; Parker, L. N.; Jun, I.; Garrett, H. B.

2007-01-01

We use a 1-D bulk charging model to evaluate dielectric charging at cryogenic temperatures relevant to space systems using passive cooling to <100K or extended operations in permanently dark lunar craters and the lunar night.

Longitudinal dynamics of an intense electron beam

NASA Astrophysics Data System (ADS)

Harris, John Richardson

2005-11-01

The dynamics of charged particle beams are governed by the particles' thermal velocities, external focusing forces, and Coulomb forces. Beams in which Coulomb forces play the dominant role are known as space charge dominated, or intense. Intense beams are of great interest for heavy ion fusion, spallation neutron sources, free-electron lasers, and other applications. In addition, all beams of interest are dominated by space charge forces when they are first created, so an understanding of space charge effects is critical to explain the later evolution of any beam. Historically, more attention has been paid to the transverse dynamics of beams. However, many interesting and important effects in beams occur along their length. These longitudinal effects can be limiting factors in many systems. For example, modulation or structure applied to the beam at low energy will evolve under space charge forces. Depending on the intended use of the beam and the nature of the modulation, this may result in improved or degraded performance. To study longitudinal dynamics in intense beams, experiments were conducted using the University of Maryland Electron Ring, a 10 keV, 100 mA electron transport system. These experiments concentrated on space charge driven changes in beam length in parabolic and rectangular beams, beam density and velocity modulation, and space charge wave propagation. Coupling between the transverse and longitudinal dynamics was also investigated. These experiments involved operating the UMER gun in space charge limited, temperature limited, triode amplification, photon limited, and hybrid modes. Results of these experiments are presented here, along with a theoretical framework for understanding the longitudinal dynamics of intense beams.

Negative differential mobility for negative carriers as revealed by space charge measurements on crosslinked polyethylene insulated model cables

NASA Astrophysics Data System (ADS)

Teyssedre, G.; Vu, T. T. N.; Laurent, C.

2015-12-01

Among features observed in polyethylene materials under relatively high field, space charge packets, consisting in a pulse of net charge that remains in the form of a pulse as it crosses the insulation, are repeatedly observed but without complete theory explaining their formation and propagation. Positive charge packets are more often reported, and the models based on negative differential mobility(NDM) for the transport of holes could account for some charge packets phenomenology. Conversely, NDM for electrons transport has never been reported so far. The present contribution reports space charge measurements by pulsed electroacoustic method on miniature cables that are model of HVDC cables. The measurements were realized at room temperature or with a temperature gradient of 10 °C through the insulation under DC fields on the order 30-60 kV/mm. Space charge results reveal systematic occurrence of a negative front of charges generated at the inner electrode that moves toward the outer electrode at the beginning of the polarization step. It is observed that the transit time of the front of negative charge increases, and therefore the mobility decreases, with the applied voltage. Further, the estimated mobility, in the range 10-14-10-13 m2 V-1 s-1 for the present results, increases when the temperature increases for the same condition of applied voltage. The features substantiate the hypothesis of negative differential mobility used for modelling space charge packets.

Solar photoionization as a loss mechanism of neutral interstellar hydrogen in interplanetary space

NASA Technical Reports Server (NTRS)

Ogawa, H. S.; Wu, C. Y. Robert; Gangopadhyay, P.; Judge, D. L.

1995-01-01

Two primary loss mechanisms of interstellar neutral hydrogen in interplanetary space are resonance charge exchange ionization with solar wind protons and photoionization by solar EUV radiation. The later process has often been neglected since the average photoionization rate has been estimated to be as much as 5 to 10 times smaller than the charge exchange rate. These factors are based on ionization rates from early measurements of solar EUV and solar wind fluxes. Using revised solar EUV and solar wind fluxes measured near the ecliptic plane we have reinvestigated the ionization rates of interplanetary hydrogen. The result of our analysis indicates that indeed the photoionization rate during solar minimum can be smaller than charge exchange by a factor of 5; however, during solar maximum conditions when solar EUV fluxes are high, and solar wind fluxes are low, photoionization can be over 60% of the charge exchange rate at Earth orbit. To obtain an accurate estimate of the importance of photoionization relative to charge exchange, we have included photoionization from both the ground and metastable states of hydrogen. We find, however, that the photoionization from the metastable state does not contribute significantly to the overall photoionization rate.

Space charge dynamic of irradiated cyanate ester/epoxy at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Wang, Shaohe; Tu, Youping; Fan, Linzhen; Yi, Chengqian; Wu, Zhixiong; Li, Laifeng

2018-03-01

Glass fibre reinforced polymers (GFRPs) have been widely used as one of the main electrical insulating structures for superconducting magnets. A new type of GFRP insulation material using cyanate ester/epoxy resin as a matrix was developed in this study, and the samples were irradiated by Co-60 for 1 MGy and 5 MGy dose. Space charge distributed within the sample were tested using the pulsed electroacoustic method, and charge concentration was found at the interfaces between glass fibre and epoxy resin. Thermally stimulated current (TSC) and dc conduction current were also tested to evaluate the irradiation effect. It was supposed that charge mobility and density were suppressed at the beginning due to the crosslinking reaction, and for a higher irradiation dose, molecular chain degradation dominated and led to more sever space charge accumulation at interfaces which enhance the internal electric field higher than the external field, and transition field for conduction current was also decreased by irradiation. Space charge dynamic at cryogenic temperature was revealed by conduction current and TSC, and space charge injection was observed for the irradiated samples at 225 K, which was more obvious for the irradiated samples.

Intensity limits of the PSI Injector II cyclotron

NASA Astrophysics Data System (ADS)

Kolano, A.; Adelmann, A.; Barlow, R.; Baumgarten, C.

2018-03-01

We investigate limits on the current of the PSI Injector II high intensity separate-sector isochronous cyclotron, in its present configuration and after a proposed upgrade. Accelerator Driven Subcritical Reactors, neutron and neutrino experiments, and medical isotope production all benefit from increases in current, even at the ∼ 10% level: the PSI cyclotrons provide relevant experience. As space charge dominates at low beam energy, the injector is critical. Understanding space charge effects and halo formation through detailed numerical modelling gives clues on how to maximise the extracted current. Simulation of a space-charge dominated low energy high intensity (9.5 mA DC) machine, with a complex collimator set up in the central region shaping the bunch, is not trivial. We use the OPAL code, a tool for charged-particle optics calculations in large accelerator structures and beam lines, including 3D space charge. We have a precise model of the present (production) Injector II, operating at 2.2 mA current. A simple model of the proposed future (upgraded) configuration of the cyclotron is also investigated. We estimate intensity limits based on the developed models, supported by fitted scaling laws and measurements. We have been able to perform more detailed analysis of the bunch parameters and halo development than any previous study. Optimisation techniques enable better matching of the simulation set-up with Injector II parameters and measurements. We show that in the production configuration the beam current scales to the power of three with the beam size. However, at higher intensities, 4th power scaling is a better fit, setting the limit of approximately 3 mA. Currents of over 5 mA, higher than have been achieved to date, can be produced if the collimation scheme is adjusted.

Correlation of ISS Electric Potential Variations with Mission Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda Neergaard

2014-01-01

Spacecraft charging on the International Space Station (ISS) is caused by a complex combination of the low Earth orbit plasma environment, space weather events, operations of the high voltage solar arrays, and changes in the ISS configuration and orbit parameters. Measurements of the ionospheric electron density and temperature along the ISS orbit and variations in the ISS electric potential are obtained from the Floating Potential Measurement Unit (FPMU) suite of four plasma instruments (two Langmuir probes, a Floating Potential Probe, and a Plasma Impedance Probe) on the ISS. These instruments provide a unique capability for monitoring the response of the ISS electric potential to variations in the space environment, changes in vehicle configuration, and operational solar array power manipulation. In particular, rapid variations in ISS potential during solar array operations on time scales of tens of milliseconds can be monitored due to the 128 Hz sample rate of the Floating Potential Probe providing an interesting insight into high voltage solar array interaction with the space plasma environment. Comparing the FPMU data with the ISS operations timeline and solar array data provides a means for correlating some of the more complex and interesting ISS electric potential variations with mission operations. In addition, recent extensions and improvements to the ISS data downlink capabilities have allowed more operating time for the FPMU than ever before. The FPMU was operated for over 200 days in 2013 resulting in the largest data set ever recorded in a single year for the ISS. In this paper we provide examples of a number of the more interesting ISS charging events observed during the 2013 operations including examples of rapid charging events due to solar array power operations, auroral charging events, and other charging behavior related to ISS mission operations.

Correlation of ISS Electric Potential Variations with Mission Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda Neergaard

2014-01-01

Spacecraft charging on the International Space Station (ISS) is caused by a complex mix of the low Earth orbit plasma environment, space weather events, operations of the high voltage solar arrays, and changes in the ISS configuration and orbit parameters. Measurements of the ionospheric electron density and temperature along the ISS orbit and variations in the ISS electric potential are obtained from the Floating Potential Measurement Unit (FPMU) suite of four plasma instruments (two Langmuir probes, a Floating Potential Probe, and a Plasma Impedance Probe) on the ISS. These instruments provide a unique capability for monitoring the response of the ISS electric potential to variations in the space environment, changes in vehicle configuration, and operational solar array power manipulation. In particular, rapid variations in ISS potential during solar array operations on time scales of tens of milliseconds can be monitored due to the 128 Hz sample rate of the Floating Potential Probe providing an interesting insight into high voltage solar array interaction with the space plasma environment. Comparing the FPMU data with the ISS operations timeline and solar array data provides a means for correlating some of the more complex and interesting ISS electric potential variations with mission operations. In addition, recent extensions and improvements to the ISS data downlink capabilities have allowed more operating time for the FPMU than ever before. The FPMU was operated for over 200 days in 2013 resulting in the largest data set ever recorded in a single year for the ISS. This presentation will provide examples of a number of the more interesting ISS charging events observed during the 2013 operations including examples of rapid charging events due to solar array power operations, auroral charging events, and other charging behavior related to ISS mission operations.

ION SOURCE WITH SPACE CHARGE NEUTRALIZATION

DOEpatents

Flowers, J.W.; Luce, J.S.; Stirling, W.L.

1963-01-22

This patent relates to a space charge neutralized ion source in which a refluxing gas-fed arc discharge is provided between a cathode and a gas-fed anode to provide ions. An electron gun directs a controlled, monoenergetic electron beam through the discharge. A space charge neutralization is effected in the ion source and accelerating gap by oscillating low energy electrons, and a space charge neutralization of the source exit beam is effected by the monoenergetic electron beam beyond the source exit end. The neutralized beam may be accelerated to any desired energy at densities well above the limitation imposed by Langmuir-Child' s law. (AEC)

International Space Station (ISS) Plasma Contactor Unit (PCU) Utilization Plan Assessment Update

NASA Technical Reports Server (NTRS)

Hernandez-Pellerano, Amri; Iannello, Christopher J.; Garrett, Henry B.; Ging, Andrew T.; Katz, Ira; Keith, R. Lloyd; Minow, Joseph I.; Willis, Emily M.; Schneider, Todd A.; Whittlesey, Edward J.;

1990 IEEE Annual Conference on Nuclear and Space Radiation Effects, 27th, Reno, NV, July 16-20, 1990, Proceedings

NASA Technical Reports Server (NTRS)

Fleetwood, Daniel M. (Editor)

1990-01-01

Various papers on nuclear and space radiation effects are presented. The general topics addressed include: basic mechanisms of radiation effects, dosimetry and energy-dependent effects, hardness assurance and testing techniques, single-event upset and latchup, isolation technologies, device and integrated circuit effects and hardening, spacecraft charging and electromagnetic effects.

Annual Conference on Nuclear and Space Radiation Effects, 17th, Cornell University, Ithaca, N.Y., July 15-18, 1980, Proceedings

NASA Technical Reports Server (NTRS)

Mcgarrity, J. M.

1980-01-01

The conference covered the radiation effects on devices, circuits, and systems, physics and basic radiation effects in materials, dosimetry and radiation transport, spacecraft charging, and space radiation effects. Other subjects included single particle upset phenomena, systems-generated electromagnetic pulse phenomena, fabrication of hardened components, testing techniques, and hardness assurance.

Airlock Battery Charge module

NASA Image and Video Library

2008-06-06

S124-E-006862 (6 June 2008) --- One of a series of digital still images documenting the Japanese Experiment Module, or JEM, also called Kibo, in its new home on the International Space Station, this view depicts Kibo's exterior in the distance, joined in the frame by some not so permanent hardware. The pictured components include the visiting Space Shuttle Discovery and a Russian Progress resupply vehicle.

Time dependent charging of layer clouds in the global electric circuit

NASA Astrophysics Data System (ADS)

Zhou, Limin; Tinsley, Brian A.

2012-09-01

There is much observational data consistent with the hypothesis that the ionosphere-earth current density (Jz) in the global electric circuit, which is modulated by both solar activity and thunderstorm activity, affects atmospheric dynamics and cloud cover. One candidate mechanism involves Jz causing the accumulation of space charge on droplets and aerosol particles, that affects the rate of scavenging of the latter, notably those of Cloud Condensation Nuclei (CCN) and Ice Forming Nuclei (IFN) (Tinsley, 2008, 2010). Space charge is the difference, per unit volume, between total positive and total negative electrical charge that is on droplets, aerosol particles (including the CCN and IFN) and air ions. The cumulative effects of the scavenging in stratiform clouds and aerosol layers in an air mass over the lifetime of the aerosol particles of 1-10 days affects the concentration and size distribution of the CCN, so that in subsequent episodes of cloud formation (including deep convective clouds) there can be effects on droplet size distribution, coagulation, precipitation processes, and even storm dynamics.Because the time scales for charging for some clouds can be long compared to cloud lifetimes, the amount of charge at a given time, and its effect on scavenging, depend more on the charging rate than on the equilibrium charge that would eventually be attained. To evaluate this, a new time-dependent charging model has been developed. The results show that for typical altostratus clouds with typical droplet radii 10 μm and aerosol particles of radius of 0.04 μm, the time constant for charging in response to a change in Jz is about 800 s, which is comparable to cloud formation and dissipation timescales for some cloud situations. The charging timescale is found to be strong functions of altitude and aerosol concentration, with the time constant for droplet charging at 2 km in air with a high concentration of aerosols being about an hour, and for clouds at 10 km in clean air being about a minute. The charging timescale is also a strong function of droplet size, with the rate for 15 μm radii droplets being about 70% longer than that for 10 μm droplets, and the rate for 5 μm radii droplets being about 50% smaller. The equilibrium charges accumulated on droplets ranged from tens to hundreds of elementary charges, which is comparable to observed values, and to vary approximately directly with Jz and inversely with the ion production rate q, which is due to the Galactic Cosmic Ray (GCR) flux and depends strongly on altitude.For the case of Jz varying directly with q, which to some extent is the case during Forbush decreases of the GCR flux, the effects on the equilibrium charge tend to cancel. In one run with the model, both q and Jz were decreased by 30%. There was little change in equilibrium charge, but the timescale for charging increased by about 40%, or equivalently, the rate of charging decreased by about 40%. Thus, for exploring the hypothesis that space charge provides a link between GCR (and other inputs that modulate Jz) and changes in clouds and atmospheric dynamics, it is necessary to consider variations in the rate of charging. The present work is intended to provide illustrative examples of time dependent charging for several different types of layer clouds.

Space and surface charge behavior analysis of charge-eliminated polymer films

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

Oda, Tetsuji; Takashima, Kazunori; Ichiyama, Shinichiro

1995-12-31

Charge behavior of corona-charged or charge eliminated polymer films being dipped in the city water were studied. They were polytetrafluoroethylene (PTFE teflon{trademark}), polypropylene (PP), low density or high density polyethylene (LDPE or HDPE) thin films which are as grown (native) or plasma-processed. The plasma processing at low pressure was tested as antistatic processing. Charge elimination was done by being dipped in alcohol or city water. TSDC analysis and surface charge profile measurement were done for both charged and charge eliminated polymer films. Surface charge density of plasma processed polymer films just after corona charging is roughly the same as thatmore » of an original film. There is little difference between surface charge density profile of a native film and that of a plasma processed film. A large hetero current peak of TSDC was observed at room temperature for a processed film. It was found that the hetero peak disappears after charge elimination process. A pressure pulse wave method by using a pulse-driven piezoelectric PVDF polymer film as a piezoelectric actuator was newly developed to observe real space charge distribution. A little difference of internal space charge distribution between the plasma processed film and the native one after corona charging is found.« less

Space charge characteristics of fluorinated polyethylene: Different effects of fluorine and oxygen

NASA Astrophysics Data System (ADS)

Zhao, Ni; Nie, Yongjie; Li, Shengtao

2018-04-01

Direct fluorination are proved having obvious effect on space charge characteristics of polyethylene. It is believed that fluorine has a positive effect on suppressing space charge injection while oxygen impurity has a negative effect. However, the mechanism for the opposite effect of fluorine and oxygen is still not clear. In this paper, the different effects of fluorine and oxygen on space charge characteristics of fluorinated low density polyethylene (LDPE) are investigated on the basis of dielectric property, chemical constitutes and trap performance of surface fluorinated layers. The results show that direct fluorination has obvious effect on chemical constitutes and dielectric properties of surface fluorinated layer. Introduced fluorine is the main factor for suppressing charge injection from the electrodes, because it seriously changes the chemical constitutes and further the trap properties of the surface fluorinated layer. While introduction of oxygen results in heterocharges and makes space charge distribution complex, due to the ionization of generated small groups like C=O containing groups. Moreover, direct fluorination will result in cleavage of some LDPE molecules whatever there is oxygen impurity or not.

Space-charge Effect on Electroresistance in Metal-Ferroelectric-Metal capacitors

PubMed Central

Tian, Bo Bo; Liu, Yang; Chen, Liu Fang; Wang, Jian Lu; Sun, Shuo; Shen, Hong; Sun, Jing Lan; Yuan, Guo Liang; Fusil, Stéphane; Garcia, Vincent; Dkhil, Brahim; Meng, Xiang Jian; Chu, Jun Hao

2015-01-01

Resistive switching through electroresistance (ER) effect in metal-ferroelectric-metal (MFM) capacitors has attracted increasing interest due to its potential applications as memories and logic devices. However, the detailed electronic mechanisms resulting in large ER when polarisation switching occurs in the ferroelectric barrier are still not well understood. Here, ER effect up to 1000% at room temperature is demonstrated in C-MOS compatible MFM nanocapacitors with a 8.8 nm-thick poly(vinylidene fluoride) (PVDF) homopolymer ferroelectric, which is very promising for silicon industry integration. Most remarkably, using theory developed for metal-semiconductor rectifying contacts, we derive an analytical expression for the variation of interfacial barrier heights due to space-charge effect that can interpret the observed ER response. We extend this space-charge model, related to the release of trapped charges by defects, to MFM structures made of ferroelectric oxides. This space-charge model provides a simple and straightforward tool to understand recent unusual reports. Finally, this work suggests that defect-engineering could be an original and efficient route for tuning the space-charge effect and thus the ER performances in future electronic devices. PMID:26670138

Space-charge Effect on Electroresistance in Metal-Ferroelectric-Metal capacitors

NASA Astrophysics Data System (ADS)

Tian, Bo Bo; Liu, Yang; Chen, Liu Fang; Wang, Jian Lu; Sun, Shuo; Shen, Hong; Sun, Jing Lan; Yuan, Guo Liang; Fusil, Stéphane; Garcia, Vincent; Dkhil, Brahim; Meng, Xiang Jian; Chu, Jun Hao

2015-12-01

Resistive switching through electroresistance (ER) effect in metal-ferroelectric-metal (MFM) capacitors has attracted increasing interest due to its potential applications as memories and logic devices. However, the detailed electronic mechanisms resulting in large ER when polarisation switching occurs in the ferroelectric barrier are still not well understood. Here, ER effect up to 1000% at room temperature is demonstrated in C-MOS compatible MFM nanocapacitors with a 8.8 nm-thick poly(vinylidene fluoride) (PVDF) homopolymer ferroelectric, which is very promising for silicon industry integration. Most remarkably, using theory developed for metal-semiconductor rectifying contacts, we derive an analytical expression for the variation of interfacial barrier heights due to space-charge effect that can interpret the observed ER response. We extend this space-charge model, related to the release of trapped charges by defects, to MFM structures made of ferroelectric oxides. This space-charge model provides a simple and straightforward tool to understand recent unusual reports. Finally, this work suggests that defect-engineering could be an original and efficient route for tuning the space-charge effect and thus the ER performances in future electronic devices.

MODELING PARTICULATE CHARGING IN ESPS

EPA Science Inventory

In electrostatic precipitators there is a strong interaction between the particulate space charge and the operating voltage and current of an electrical section. Calculating either the space charge or the operating point when the other is fixed is not difficult, but calculating b...

Ground-Based High-Power Microwave Decoy Discrimination System.

DTIC Science & Technology

1987-12-23

understanding of plasma instabilities, self-induced magnetic effects , space - charge considerations, production of ion currents, etc. 3.3.4 Cross-Field...breakdown, due to small potential differences. Interaction volumes can therefore be large, avoiding breakdown and space - charge effects (at the price...the interference of the incident and reflected wave, and by the electrostatic forces of the surface (positive) and space charge (negative) trapped in

Design guidelines for assessing and controlling spacecraft charging effects

NASA Technical Reports Server (NTRS)

Purvis, C. K.; Garrett, H. B.; Whittlesey, A. C.; Stevens, N. J.

1984-01-01

The need for uniform criteria, or guidelines, to be used in all phases of spacecraft design is discussed. Guidelines were developed for the control of absolute and differential charging of spacecraft surfaces by the lower energy space charged particle environment. Interior charging due to higher energy particles is not considered. A guide to good design practices for assessing and controlling charging effects is presented. Uniform design practices for all space vehicles are outlined.

Design guidelines for assessing and controlling spacecraft charging effects

NASA Technical Reports Server (NTRS)

Purvis, C. K.; Garrett, H. B.; Whittlesey, A.; Stevens, N. J.

1985-01-01

The need for uniform criteria, or guidelines, to be used in all phases of spacecraft design is discussed. Guidelines were developed for the control of absolute and differential charging of spacecraft surfaces by the lower energy space charged particle environment. Interior charging due to higher energy particles is not considered. A guide to good design practices for assessing and controlling charging effects is presented. Uniform design practices for all space vehicles are outlined.

The influence of pre-conditioning on space charge formation in LDPE

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

Fleming, R.J.; Henriksen, M.; Holboell, J.T.

1996-12-31

In this paper the authors present space charge accumulation data for planar low density polyethylene samples subjected to 20kV/mm dc fields at room temperature. The data were obtained using the laser-induced-pressure-pulse (LIPP) technique. Some of the samples were conditioned by holding them at 40 C in short-circuit at rotary pump pressure for 48hr prior to measurement. Such conditioning had no consistent effect on the space charge. The extent of charge injection/extraction at the semicon electrodes appeared to vary considerably between samples.

Scaling for quantum tunneling current in nano- and subnano-scale plasmonic junctions.

PubMed

Zhang, Peng

2015-05-19

When two conductors are separated by a sufficiently thin insulator, electrical current can flow between them by quantum tunneling. This paper presents a self-consistent model of tunneling current in a nano- and subnano-meter metal-insulator-metal plasmonic junction, by including the effects of space charge and exchange correlation potential. It is found that the J-V curve of the junction may be divided into three regimes: direct tunneling, field emission, and space-charge-limited regime. In general, the space charge inside the insulator reduces current transfer across the junction, whereas the exchange-correlation potential promotes current transfer. It is shown that these effects may modify the current density by orders of magnitude from the widely used Simmons' formula, which is only accurate for a limited parameter space (insulator thickness > 1 nm and barrier height > 3 eV) in the direct tunneling regime. The proposed self-consistent model may provide a more accurate evaluation of the tunneling current in the other regimes. The effects of anode emission and material properties (i.e. work function of the electrodes, electron affinity and permittivity of the insulator) are examined in detail in various regimes. Our simple model and the general scaling for tunneling current may provide insights to new regimes of quantum plasmonics.

Scaling for quantum tunneling current in nano- and subnano-scale plasmonic junctions

PubMed Central

Zhang, Peng

2015-01-01

When two conductors are separated by a sufficiently thin insulator, electrical current can flow between them by quantum tunneling. This paper presents a self-consistent model of tunneling current in a nano- and subnano-meter metal-insulator-metal plasmonic junction, by including the effects of space charge and exchange correlation potential. It is found that the J-V curve of the junction may be divided into three regimes: direct tunneling, field emission, and space-charge-limited regime. In general, the space charge inside the insulator reduces current transfer across the junction, whereas the exchange-correlation potential promotes current transfer. It is shown that these effects may modify the current density by orders of magnitude from the widely used Simmons’ formula, which is only accurate for a limited parameter space (insulator thickness > 1 nm and barrier height > 3 eV) in the direct tunneling regime. The proposed self-consistent model may provide a more accurate evaluation of the tunneling current in the other regimes. The effects of anode emission and material properties (i.e. work function of the electrodes, electron affinity and permittivity of the insulator) are examined in detail in various regimes. Our simple model and the general scaling for tunneling current may provide insights to new regimes of quantum plasmonics. PMID:25988951

Negative differential mobility for negative carriers as revealed by space charge measurements on crosslinked polyethylene insulated model cables

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

Teyssedre, G., E-mail: gilbert.teyssedre@laplace.univ-tlse.fr; Laurent, C.; CNRS, LAPLACE, F-31062 Toulouse

Among features observed in polyethylene materials under relatively high field, space charge packets, consisting in a pulse of net charge that remains in the form of a pulse as it crosses the insulation, are repeatedly observed but without complete theory explaining their formation and propagation. Positive charge packets are more often reported, and the models based on negative differential mobility(NDM) for the transport of holes could account for some charge packets phenomenology. Conversely, NDM for electrons transport has never been reported so far. The present contribution reports space charge measurements by pulsed electroacoustic method on miniature cables that are modelmore » of HVDC cables. The measurements were realized at room temperature or with a temperature gradient of 10 °C through the insulation under DC fields on the order 30–60 kV/mm. Space charge results reveal systematic occurrence of a negative front of charges generated at the inner electrode that moves toward the outer electrode at the beginning of the polarization step. It is observed that the transit time of the front of negative charge increases, and therefore the mobility decreases, with the applied voltage. Further, the estimated mobility, in the range 10{sup −14}–10{sup −13} m{sup 2} V{sup −1} s{sup −1} for the present results, increases when the temperature increases for the same condition of applied voltage. The features substantiate the hypothesis of negative differential mobility used for modelling space charge packets.« less

Physical interactions of charged particles for radiotherapy and space applications.

PubMed

Zeitlin, Cary

2012-11-01

In this paper, the basic physics by which energetic charged particles deposit energy in matter is reviewed. Energetic charged particles are used for radiotherapy and are encountered in spaceflight, where they pose a health risk to astronauts. They interact with matter through nuclear and electromagnetic forces. Deposition of energy occurs mostly along the trajectory of the incoming particle, but depending on the type of incident particle and its energy, there is some nonzero probability for energy deposition relatively far from the nominal trajectory, either due to long-ranged knock-on electrons (sometimes called delta rays) or from the products of nuclear fragmentation, including neutrons. In the therapy setting, dose localization is of paramount importance, and the deposition of energy outside nominal treatment volumes complicates planning and increases the risk of secondary cancers as well as noncancer effects in normal tissue. Statistical effects are also important and will be discussed. In contrast to radiation therapy patients, astronauts in space receive comparatively small whole-body radiation doses from energetic charged particles and associated secondary radiation. A unique aspect of space radiation exposures is the high-energy heavy-ion component of the dose. This is not present in terrestrial exposures except in carbon-ion radiotherapy. Designers of space missions must limit exposures to keep risk within acceptable limits. These limits are, at present, defined for low-Earth orbit, but not for deep-space missions outside the geomagnetosphere. Most of the uncertainty in risk assessment for such missions comes from the lack of understanding of the biological effectiveness of the heavy-ion component, with a smaller component due to uncertainties in transport physics and dosimetry. These same uncertainties are also critical in the therapy setting.

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer

DOE PAGES

Dell'Angela, M.; Anniyev, T.; Beye, M.; ...

2015-03-01

Vacuum space charge-induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer.

PubMed

Dell'Angela, M; Anniyev, T; Beye, M; Coffee, R; Föhlisch, A; Gladh, J; Kaya, S; Katayama, T; Krupin, O; Nilsson, A; Nordlund, D; Schlotter, W F; Sellberg, J A; Sorgenfrei, F; Turner, J J; Öström, H; Ogasawara, H; Wolf, M; Wurth, W

2015-03-01

Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

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

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588

2016-05-15

The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-chargemore » wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.« less

Internal electric fields of electrolytic solutions induced by space-charge polarization

NASA Astrophysics Data System (ADS)

Sawada, Atsushi

2006-10-01

The dielectric dispersion of electrolytic solutions prepared using chlorobenzene as a solvent and tetrabutylammonium tetraphenylborate as a solute is analyzed in terms of space-charge polarization in order to derive the ionic constants, and the Stokes radius obtained is discussed in comparison with the values that have been measured by conductometry. A homogeneous internal electric field is assumed for simplicity in the analysis of the space-charge polarization. The justification of the approximation by the homogeneous field is discussed from two points of view: one is the accuracy of the Stokes radius value observed and the other is the effect of bound charges on electrodes in which they level the highly inhomogeneous field, which has been believed in the past. In order to investigate the actual electric field, numerical calculations based on the Poisson equation are carried out by considering the influence of the bound charges. The variation of the number of bound charges with time is clarified by determining the relaxation function of the dielectric constant attributed to the space-charge polarization. Finally, a technique based on a two-field approximation, where homogeneous and hyperbolic fields are independently applied in relevant frequency ranges, is introduced to analyze the space-charge polarization of the electrolytic solutions, and further improvement of the accuracy in the determination of the Stokes radius is achieved.

Understanding cancer development processes after HZE-particle exposure: roles of ROS, DNA damage repair and inflammation.

PubMed

Sridharan, D M; Asaithamby, A; Bailey, S M; Costes, S V; Doetsch, P W; Dynan, W S; Kronenberg, A; Rithidech, K N; Saha, J; Snijders, A M; Werner, E; Wiese, C; Cucinotta, F A; Pluth, J M

2015-01-01

During space travel astronauts are exposed to a variety of radiations, including galactic cosmic rays composed of high-energy protons and high-energy charged (HZE) nuclei, and solar particle events containing low- to medium-energy protons. Risks from these exposures include carcinogenesis, central nervous system damage and degenerative tissue effects. Currently, career radiation limits are based on estimates of fatal cancer risks calculated using a model that incorporates human epidemiological data from exposed populations, estimates of relative biological effectiveness and dose-response data from relevant mammalian experimental models. A major goal of space radiation risk assessment is to link mechanistic data from biological studies at NASA Space Radiation Laboratory and other particle accelerators with risk models. Early phenotypes of HZE exposure, such as the induction of reactive oxygen species, DNA damage signaling and inflammation, are sensitive to HZE damage complexity. This review summarizes our current understanding of critical areas within the DNA damage and oxidative stress arena and provides insight into their mechanistic interdependence and their usefulness in accurately modeling cancer and other risks in astronauts exposed to space radiation. Our ultimate goals are to examine potential links and crosstalk between early response modules activated by charged particle exposure, to identify critical areas that require further research and to use these data to reduced uncertainties in modeling cancer risk for astronauts. A clearer understanding of the links between early mechanistic aspects of high-LET response and later surrogate cancer end points could reveal key nodes that can be therapeutically targeted to mitigate the health effects from charged particle exposures.

Engineering charge ordering into multiferroicity

NASA Astrophysics Data System (ADS)

He, Xu; Jin, Kui-juan

2016-04-01

Multiferroic materials have attracted great interest but are rare in nature. In many transition-metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superlattice. One example of the model demonstrated here is the perovskite (LaFeO3)2/LaTiO3 (111) superlattice, in which the LaTiO3 layer acts as the donor and the spacing layer, and the LaFeO3 layer is half doped and performs charge ordering. The collaboration of the charge ordering and the spacing layer breaks the space inversion symmetry, resulting in a large ferroelectric polarization. As the charge ordering also leads to a ferrimagnetic structure, (LaFeO3)2/LaTiO3 is multiferroic. It is expected that this work can encourage the designing and experimental implementation of a large class of multiferroic structures with novel properties.

Effect of Layer Charge on CO2 and H2O Intercalations in Swelling Clays.

PubMed

Rao, Qi; Leng, Yongsheng

2016-11-08

The effect of layer charge on the intercalation of supercritical carbon dioxide (scCO 2 )-H 2 O mixture in Na-montmorillonite clay interlayers under T = 323 K and P = 90 bar geologic sequestration conditions has been further investigated. This effect includes the charge amount and its location (within either octahedral or tetrahedral layers due to isomorphic substitutions). Two clay models with different layer charges are used in this study. Simulation results show that the increase of charge amount shifts the monolayer-to-bilayer (1W-to-2W) hydration transition toward the lower relative humidity (RH), increasing water sorption at the expense of reducing the overall sorption amount of CO 2 in the clay interlayer. However, the combination of the influence of charge amount and charge location leads to insignificant changes in equilibrium basal spacings of the high- and low-charge clays. Molecular dynamics simulations show that the CO 2 dimers, which are frequently seen in low-charge clay interlayers, vanish in high-charge clay interlayers even at low RH of 30%.

Space Charge Modulated Electrical Breakdown

PubMed Central

Li, Shengtao; Zhu, Yuanwei; Min, Daomin; Chen, George

2016-01-01

Electrical breakdown is one of the most important physical phenomena in electrical and electronic engineering. Since the early 20th century, many theories and models of electrical breakdown have been proposed, but the origin of one key issue, that the explanation for dc breakdown strength being twice or higher than ac breakdown strength in insulating materials, remains unclear. Here, by employing a bipolar charge transport model, we investigate the space charge dynamics in both dc and ac breakdown processes. We demonstrate the differences in charge accumulations under both dc and ac stresses and estimate the breakdown strength, which is modulated by the electric field distortion induced by space charge. It is concluded that dc breakdown initializes in the bulk whereas ac breakdown initializes in the vicinity of the sample-electrode interface. Compared with dc breakdown, the lower breakdown strength under ac stress and the decreasing breakdown strength with an increase in applied frequency, are both attributed to the electric field distortion induced by space charges located in the vicinity of the electrodes. PMID:27599577

Process of breaking and rendering permeable a subterranean rock mass

DOEpatents

Lekas, Mitchell A.

1980-01-01

The process of the present invention involves the following steps: producing, as by hydrofracing, a substantially horizontal fracture in the subterranean rock mass to be processed; emplacing an explosive charge in the mass in spaced juxtaposed position to the fracture; enlarging the fracture to create a void space thereat, an initial lifting of the overburden, and to provide a free face juxtaposed to and arranged to cooperate with the emplaced explosive charge; and exploding the charge against the free face for fragmenting the rock and to distribute the space, thus providing fractured, pervious, rubble-ized rock in an enclosed subterranean chamber. Firing of the charge provides a further lifting of the overburden, an enlargement of the chamber and a larger void space to distribute throughout the rubble-ized rock within the chamber. In some forms of the invention an explosive charge is used to produce a transitory enlargement of the fracture, and the juxtaposed emplaced charge is fired during the critical period of enlargement of the fracture.

The effect of plasma density and emitter geometry on space charge limits for field emitter array electron charge emission into a space plasma

NASA Astrophysics Data System (ADS)

Morris, Dave; Gilchrist, Brian; Gallimore, Alec

2001-02-01

Field Emitter Array Cathodes (FEACs) are a new technology being developed for several potential spacecraft electron emission and charge control applications. Instead of a single hot (i.e., high powered) emitter, or a gas dependant plasma contactor, FEAC systems consist of many (hundreds or thousands) of small (micron level) cathode/gate pairs printed on a semiconductor wafer that effect cold field emission at relatively low voltages. Each individual cathode emits only micro-amp level currents, but a functional array is capable of amp/cm2 current densities. It is hoped that thus FEAC offers the possibility of a relatively low-power, simple to integrate, and inexpensive technique for the high level of current emissions that are required for an electrodynamic tether (EDT) propulsion mission. Space charge limits are a significant concern for the EDT application. Vacuum chamber tests and PIC simulations are being performed at the University of Michigan Plasmadynamics and Electric Propulsion Laboratory and Space Physics Research Laboratory to determine the effect of plasma density and emitter geometry on space charge limitations. The results of this work and conclusions to date of how to best mitigate space charge limits will be presented. .

Charged Particle lunar Environment Experiment (CPLEE)

NASA Technical Reports Server (NTRS)

Reasoner, D. L.

1974-01-01

Research development in the Charged Particle Lunar Environment Experiment (CPLEE) is reported. The CPLEE is ion-electron spectrometer placed on the lunar surface for the purpose of measuring charged particle fluxes impacting the moon from a variety of regions and to study the interactions between space plasmas and the lunar surface. The principal accomplishments reported include: (1) furnishing design specifications for construction of the CPLEE instruments; (2) development of an advanced computer-controlled facility for automated instrument calibration; (3) active participation in the deployment and past-deployment operational phases with regard to data verification and operational mode selection; and (4) publication of research papers, including a study of lunar photoelectrons, a study of plasmas resulting from man-made lunar impart events, a study of magnetotail and magnetosheath particle populations, and a study of solar-flare interplanetary particles.

Electronic Fingerprinting for Industry

NASA Technical Reports Server (NTRS)

1995-01-01

Veritec's VeriSystem is a complete identification and tracking system for component traceability, improved manufacturing and processing, and automated shop floor applications. The system includes the Vericode Symbol, a more accurate and versatile alternative to the traditional bar code, that is scanned by charge coupled device (CCD) cameras. The system was developed by Veritec, Rockwell International and Marshall Space Flight Center to identify and track Space Shuttle parts.

Stackable differential mobility analyzer for aerosol measurement

DOEpatents

Cheng, Meng-Dawn [Oak Ridge, TN; Chen, Da-Ren [Creve Coeur, MO

2007-05-08

A multi-stage differential mobility analyzer (MDMA) for aerosol measurements includes a first electrode or grid including at least one inlet or injection slit for receiving an aerosol including charged particles for analysis. A second electrode or grid is spaced apart from the first electrode. The second electrode has at least one sampling outlet disposed at a plurality different distances along its length. A volume between the first and the second electrode or grid between the inlet or injection slit and a distal one of the plurality of sampling outlets forms a classifying region, the first and second electrodes for charging to suitable potentials to create an electric field within the classifying region. At least one inlet or injection slit in the second electrode receives a sheath gas flow into an upstream end of the classifying region, wherein each sampling outlet functions as an independent DMA stage and classifies different size ranges of charged particles based on electric mobility simultaneously.

1987 Annual Conference on Nuclear and Space Radiation Effects, Snowmass Village, CO, July 28-31, 1987, Proceedings

NASA Technical Reports Server (NTRS)

1987-01-01

Various papers on nuclear and space radiation effects are presented. The general topics addressed include: basic mechanisms of radiation effects, single-event phenomena, temperature and field effects, modeling and characterization of radiation effects, IC radiation effects and hardening, and EMP/SGEMP/IEMP phenomena. Also considered are: dosimetry/energy-dependent effects, sensors in and for radiation environments, spacecraft charging and space radiation effects, radiation effects and devices, radiation effects on isolation technologies, and hardness assurance and testing techniques.

1992 IEEE Annual Conference on Nuclear and Space Radiation Effects, 29th, New Orleans, LA, July 13-17, 1992, Proceedings

NASA Technical Reports Server (NTRS)

Van Vonno, Nick W. (Editor)

1992-01-01

The papers presented in this volume provide an overview of recent theoretical and experimental research related to nuclear and space radiation effects. Topics dicussed include single event phenomena, radiation effects in particle detectors and associated electronics for accelerators, spacecraft charging, and space environments and effects. The discussion also covers hardness assurance and testing techniques, electromagnetic effects, radiation effects in devices and integrated circuits, dosimetry and radiation facilities, isolation techniques, and basic mechanisms.

100 Years of the Physics of Diodes

NASA Astrophysics Data System (ADS)

Luginsland, John

2013-10-01

The Child-Langmuir Law (CL), discovered 100 years ago, gives the maximum current that can be transported across a planar diode in the steady state. As a quintessential example of the impact of space-charge shielding near a charged surface, it is central to the studies of high current diodes, such as high power microwave sources, vacuum microelectronics, electron and ion sources, and high current drivers used in high-energy density physics experiments. CL remains a touchstone of fundamental sheath physics, including contemporary studies of nano-scale quantum diodes and plasmonic devices. Its solid state analog is the Mott-Gurney law, governing the maximum charge injection in solids, such as organic materials and other dielectrics, which is important to energy devices, such as solar cells and light-emitting diodes. This paper reviews the important advances in the physics of diodes since the discovery of CL, including virtual cathode formation and extension of CL to multiple dimensions, to the quantum regime, and to ultrafast processes. We will review the influence of magnetic fields, multiple species in bipolar flow, electromagnetic and time dependent effects in both short pulse and high frequency THz limits, and single electron regimes. Transitions from various emission mechanisms (thermionic, field, and photo-emission) to the space charge limited state (CL) will be addressed, especially highlighting important simulation and experimental developments in selected contemporary areas of study. This talk will stress the fundamental physical links between the physics of beams to limiting currents in other areas, such as low temperature plasmas, laser plasmas, and space propulsion. Also emphasized is the role of non-equilibrium phenomena associated with materials and plasmas in close contact. Work supported by the Air Force Office of Scientific Research.

Space charge induced resonance excitation in high intensity rings

NASA Astrophysics Data System (ADS)

Cousineau, S.; Lee, S. Y.; Holmes, J. A.; Danilov, V.; Fedotov, A.

2003-03-01

We present a particle core model study of the space charge effect on high intensity synchrotron beams, with specific emphasis on the Proton Storage Ring (PSR) at Los Alamos National Laboratory. Our particle core model formulation includes realistic lattice focusing and dispersion. We transport both matched and mismatched beams through real lattice structure and compare the results with those of an equivalent uniform-focusing approximation. The effects of lattice structure and finite momentum spread on the resonance behavior are specifically targeted. Stroboscopic maps of the mismatched envelope are constructed and show high-order resonances and stochastic effects that dominate at high mismatch or high intensity. We observe the evolution of the envelope phase-space structure during a high intensity PSR beam accumulation. Finally, we examine the envelope-particle parametric resonance condition and discuss the possibility for halo growth in synchrotron beams due to this mechanism.

Three dimensional δf simulations of beams in the SSC

NASA Astrophysics Data System (ADS)

Koga, J.; Tajima, T.; Machida, S.

1993-12-01

A three dimensional δf strong-strong algorithm has been developed to apply to the study of such effects as space charge and beam-beam interaction phenomena in the Superconducting Super Collider (SSC). The algorithm is obtained from the merging of the particle tracking code Simpsons used for 3 dimensional space charge effects and a δf code. The δf method is used to follow the evolution of the non-gaussian part of the beam distribution. The advantages of this method are twofold. First, the Simpsons code utilizes a realistic accelerator model including synchrotron oscillations and energy ramping in 6 dimensional phase space with electromagnetic fields of the beams calculated using a realistic 3 dimensional field solver. Second, the beams are evolving in the fully self-consistent strong-strong sense with finite particle fluctuation noise is greatly reduced as opposed to the weak-strong models where one beam is fixed.

Agreement for NASA/OAST - USAF/AFSC space interdependency on spacecraft environment interaction

NASA Technical Reports Server (NTRS)

Pike, C. P.; Stevens, N. J.

1980-01-01

A joint AF/NASA comprehensive program on spacecraft environment interactions consists of combined contractual and in house efforts aimed at understanding spacecraft environment ineraction phenomena and relating ground test results to space conditions. Activities include: (1) a concerted effort to identify project related environmental interactions; (2) a materials investigation to measure the basic properties of materials and develop or modify materials as needed; and (3) a ground simulation investigation to evaluate basic plasma interaction phenomena and provide inputs to the analytical modeling investigation. Systems performance is evaluated by both ground tests and analysis. There is an environmental impact investigation to determine the effect of future large spacecraft on the charged particle environment. Space flight investigations are planned to verify the results. The products of this program are test standards and design guidelines which summarize the technology, specify test criteria, and provide techniques to minimize or eliminate system interactions with the charged particle environment.

Efficient isoparametric integration over arbitrary space-filling Voronoi polyhedra for electronic structure calculations

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

Alam, Aftab; Khan, S. N.; Wilson, Brian G.

2011-07-06

A numerically efficient, accurate, and easily implemented integration scheme over convex Voronoi polyhedra (VP) is presented for use in ab initio electronic-structure calculations. We combine a weighted Voronoi tessellation with isoparametric integration via Gauss-Legendre quadratures to provide rapidly convergent VP integrals for a variety of integrands, including those with a Coulomb singularity. We showcase the capability of our approach by first applying it to an analytic charge-density model achieving machine-precision accuracy with expected convergence properties in milliseconds. For contrast, we compare our results to those using shape-functions and show our approach is greater than 10 5 times faster and 10more » 7 times more accurate. Furthermore, a weighted Voronoi tessellation also allows for a physics-based partitioning of space that guarantees convex, space-filling VP while reflecting accurate atomic size and site charges, as we show within KKR methods applied to Fe-Pd alloys.« less

Alternative Fuels Data Center: Plug-In Electric Vehicle Deployment Policy

Science.gov Websites

addendum to a pre-existing zoning ordinance to specify permissible use of EVSE in single- and multi-family -ready requirements may include EVSE installation, pre-wiring, or space reservation. California building charging infrastructure. Examples include the scope of EVSE pre-wiring or installation from a

The 1982 Goddard Space Flight Center Battery Workshop

NASA Technical Reports Server (NTRS)

Halpert, G. (Editor)

1983-01-01

Various topics concerned with advanced battery technology are addressed including lithium cell and battery safety developments, mathematical modelling, charge control of aerospace power systems, and the application of nickel hydrogen cells/batteries vis-a-vis nickel cadmium cells/batteries.

Investigation of space charge distribution of low-density polyethylene/GO-GNF (graphene oxide from graphite nanofiber) nanocomposite for HVDC application.

PubMed

Kim, Yoon Jin; Ha, Son-Tung; Lee, Gun Joo; Nam, Jin Ho; Ryu, Ik Hyun; Nam, Su Hyun; Park, Cheol Min; In, Insik; Kim, Jiwan; Han, Chul Jong

2013-05-01

This paper reported a research on space charge distribution in low-density polyethylene (LDPE) nanocomposites with different types of graphene and graphene oxide (GO) at low filler content (0.05 wt%) under high DC electric field. Effect of addition of graphene oxide or graphene, its dispersion in LDPE polymer matrix on the ability to suppress space charge generation will be investigated and compared with MgO/LDPE nanocomposite at the same filler concentration. At an applied electric field of 80 kV/mm, a positive packet-like charge was observed in both neat LDPE, MgO/LDPE, and graphene/LDPE nanocomposites, whereas only little homogenous space charge was observed in GO/LDPE nanocomposites, especially with GO synthesized from graphite nano fiber (GNF) which is only -100 nm in diameter. Our research also suggests that dispersion of graphene oxide particles on the polymer matrix plays a significant role to the performance of nanocomposites on suppressing packet-like space charge. From these results, it is expected that nano-sized GO synthesized from GNF can be a promising filler material to LDPE composite for HVDC applications.

Experimental study and simulation of space charge stimulated discharge

NASA Astrophysics Data System (ADS)

Noskov, M. D.; Malinovski, A. S.; Cooke, C. M.; Wright, K. A.; Schwab, A. J.

2002-11-01

The electrical discharge of volume distributed space charge in poly(methylmethacrylate) (PMMA) has been investigated both experimentally and by computer simulation. The experimental space charge was implanted in dielectric samples by exposure to a monoenergetic electron beam of 3 MeV. Electrical breakdown through the implanted space charge region within the sample was initiated by a local electric field enhancement applied to the sample surface. A stochastic-deterministic dynamic model for electrical discharge was developed and used in a computer simulation of these breakdowns. The model employs stochastic rules to describe the physical growth of the discharge channels, and deterministic laws to describe the electric field, the charge, and energy dynamics within the discharge channels and the dielectric. Simulated spatial-temporal and current characteristics of the expanding discharge structure during physical growth are quantitatively compared with the experimental data to confirm the discharge model. It was found that a single fixed set of physically based dielectric parameter values was adequate to simulate the complete family of experimental space charge discharges in PMMA. It is proposed that such a set of parameters also provides a useful means to quantify the breakdown properties of other dielectrics.

On the mechanism of pattern formation in glow dielectric barrier discharge

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

Qiao, Yajun; Li, Ben; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn

2016-01-15

The formation mechanism of pattern in glow dielectric barrier discharge is investigated by two-dimensional fluid modeling. Experimental results are shown for comparison. The simulation results show that the non-uniform distribution of space charges makes the discharge be enhanced in the high-density region but weakened in its neighborhood, which is considered as an activation-inhibition effect. This effect shows through during a current pulse (one discharge event) but also in a certain period of time after discharge that determines a driving frequency range for the non-uniformity of space charges to be enhanced. The effects of applied voltage, surface charge, electrode boundary, andmore » external field are also discussed. All these factors affect the formation of dielectric-barrier-discharge pattern by changing the distribution or the dynamics of space charges and hence the activation-inhibition effect of non-uniform space charges.« less

Optical measurements for interfacial conduction and breakdown

NASA Astrophysics Data System (ADS)

Hebner, R. E., Jr.; Kelley, E. F.; Hagler, J. N.

1983-01-01

Measurements and calculations contributing to the understanding of space and surface charges in practical insulation systems are given. Calculations are presented which indicate the size of charge densities necessary to appreciably modify the electric field from what would be calculated from geometrical considerations alone. Experimental data is also presented which locates the breakdown in an electrode system with a paper sample bridging the gap between the electrodes. It is found that with careful handling, the breakdown does not necessarily occur along the interface even if heavily contaminated oil is used. The effects of space charge in the bulk liquid are electro-optically examined in nitrobenzene and transformer oil. Several levels of contamination in transformer oil are investigated. Whereas much space charge can be observed in nitrobenzene, very little space charge, if any, can be observed in the transformer oil samples even at temperatures near 100 degrees C.

Compression of subrelativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction.

PubMed

van Oudheusden, T; Pasmans, P L E M; van der Geer, S B; de Loos, M J; van der Wiel, M J; Luiten, O J

2010-12-31

We demonstrate the compression of 95 keV, space-charge-dominated electron bunches to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are of sufficient quality to capture a diffraction pattern with a single shot, which we demonstrate by a diffraction experiment on a polycrystalline gold foil. Compression is realized by means of velocity bunching by inverting the positive space-charge-induced velocity chirp. This inversion is induced by the oscillatory longitudinal electric field of a 3 GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs.

Space Charge Effect in the Sheet and Solid Electron Beam

NASA Astrophysics Data System (ADS)

Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung

1998-11-01

We analyze the space charge effect of two different types of electron beam ; sheet and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for sheet and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting current and space charge loading in each geometries.

High Power Klystrons for Efficient Reliable High Power Amplifiers.

DTIC Science & Technology

1980-11-01

techniques to obtain high overall efficiency. One is second harmonic space charge bunching. This is a process whereby the fundamental and second harmonic...components of the space charge waves in the electron beam of a microwave tube are combined to produce more highly concentrated electron bunches raising the...the drift lengths to enhance the 2nd harmonic component in the space charge waves. The latter method was utilized in the VKC-7790. Computer

Numerical Investigation of a Cascaded Longitudinal Space-Charge Amplifier at the Fermilab's Advanced Superconducting Test Accelerator

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

Halavanau, A.; Piot, P.

2015-06-01

In a cascaded longitudinal space-charge amplifier (LSCA), initial density noise in a relativistic e-beam is amplified via the interplay of longitudinal space charge forces and properly located dispersive sections. This type of amplification process was shown to potentially result in large final density modulations [1] compatible with the production of broadband electromagnetic radiation. The technique was recently demonstrated in the optical domain [2]. In this paper we investigate, via numerical simulations, the performances of a cascaded LSCA beamline at the Fermilab’s Advanced Superconducting Test Accelerator (ASTA). We especially explore the properties of the produced broadband radiation. Our studies have beenmore » conducted with a grid-less three-dimensional space-charge algorithm.« less

Electric field and space charge distribution measurement in transformer oil struck by impulsive high voltage

NASA Astrophysics Data System (ADS)

Sima, Wenxia; Guo, Hongda; Yang, Qing; Song, He; Yang, Ming; Yu, Fei

2015-08-01

Transformer oil is widely used in power systems because of its excellent insulation properties. The accurate measurement of electric field and space charge distribution in transformer oil under high voltage impulse has important theoretical and practical significance, but still remains challenging to date because of its low Kerr constant. In this study, the continuous electric field and space charge distribution over time between parallel-plate electrodes in high-voltage pulsed transformer oil based on the Kerr effect is directly measured using a linear array photoelectrical detector. Experimental results demonstrate the applicability and reliability of this method. This study provides a feasible approach to further study the space charge effects and breakdown mechanisms in transformer oil.

14 CFR 389.12 - Payment of fees and charges.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Payment of fees and charges. 389.12 Section 389.12 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ORGANIZATION FEES AND CHARGES FOR SPECIAL SERVICES Fees for Special Services § 389.12 Payment of...

14 CFR 389.12 - Payment of fees and charges.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Payment of fees and charges. 389.12 Section 389.12 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ORGANIZATION FEES AND CHARGES FOR SPECIAL SERVICES Fees for Special Services § 389.12 Payment of...

Space experiments with particle accelerators (SEPAC): Description of instrumentation

NASA Technical Reports Server (NTRS)

Taylor, W. W. L.; Roberts, W. T.; Reasoner, D. L.; Chappell, C. R.; Baker, B. B.; Burch, J. L.; Gibson, W. C.; Black, R. K.; Tomlinson, W. M.; Bounds, J. R.

1987-01-01

SEPAC (Space Experiments with Particle Accelerators) flew on Spacelab 1 (SL 1) in November and December 1983. SEPAC is a joint U.S.-Japan investigation of the interaction of electron, plasma, and neutral beams with the ionosphere, atmosphere and magnetosphere. It is scheduled to fly again on Atlas 1 in August 1990. On SL 1, SEPAC used an electron accelerator, a plasma accelerator, and neutral gas source as active elements and an array of diagnostics to investigate the interactions. For Atlas 1, the plasma accelerator will be replaced by a plasma contactor and charge collection devices to improve vehicle charging meutralization. This paper describes the SEPAC instrumentation in detail for the SL 1 and Atlas 1 flights and includes a bibliography of SEPAC papers.

Particle-in-cell/accelerator code for space-charge dominated beam simulation

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

2012-05-08

Warp is a multidimensional discrete-particle beam simulation program designed to be applicable where the beam space-charge is non-negligible or dominant. It is being developed in a collaboration among LLNL, LBNL and the University of Maryland. It was originally designed and optimized for heave ion fusion accelerator physics studies, but has received use in a broader range of applications, including for example laser wakefield accelerators, e-cloud studies in high enery accelerators, particle traps and other areas. At present it incorporates 3-D, axisymmetric (r,z) planar (x-z) and transverse slice (x,y) descriptions, with both electrostatic and electro-magnetic fields, and a beam envelope model.more » The code is guilt atop the Python interpreter language.« less

A computer model of solar panel-plasma interactions

NASA Technical Reports Server (NTRS)

Cooke, D. L.; Freeman, J. W.

1980-01-01

High power solar arrays for satellite power systems are presently being planned with dimensions of kilometers, and with tens of kilovolts distributed over their surface. Such systems face many plasma interaction problems, such as power leakage to the plasma, particle focusing, and anomalous arcing. These effects cannot be adequately modeled without detailed knowledge of the plasma sheath structure and space charge effects. Laboratory studies of 1 by 10 meter solar array in a simulated low Earth orbit plasma are discussed. The plasma screening process is discussed, program theory is outlined, and a series of calibration models is presented. These models are designed to demonstrate that PANEL is capable of accurate self consistant space charge calculations. Such models include PANEL predictions for the Child-Langmuir diode problem.

Space-Charge Simulation of Integrable Rapid Cycling Synchrotron

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

Eldred, Jeffery; Valishev, Alexander

2017-05-01

Integrable optics is an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use a Synergia space-charge simulation to investigate the application of integrable optics to a high-intensity hadron ring that could replace the Fermilab Booster. We find that incorporating integrability into the design suppresses the beam halo generated by a mismatched KV beam. Our integrable rapid cycling synchrotron (iRCS) design includes other features of modern ring design such as low momentum compaction factor and harmonically canceling sextupoles. Experimental tests of high-intensity beams in integrable lattices will take place over the next several yearsmore » at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER).« less

Photonic crystal devices formed by a charged-particle beam

DOEpatents

Lin, Shawn-Yu; Koops, Hans W. P.

2000-01-01

A photonic crystal device and method. The photonic crystal device comprises a substrate with at least one photonic crystal formed thereon by a charged-particle beam deposition method. Each photonic crystal comprises a plurality of spaced elements having a composition different from the substrate, and may further include one or more impurity elements substituted for spaced elements. Embodiments of the present invention may be provided as electromagnetic wave filters, polarizers, resonators, sources, mirrors, beam directors and antennas for use at wavelengths in the range from about 0.2 to 200 microns or longer. Additionally, photonic crystal devices may be provided with one or more electromagnetic waveguides adjacent to a photonic crystal for forming integrated electromagnetic circuits for use at optical, infrared, or millimeter-wave frequencies.

Role of Near Substrate and Bulk Polymer Morphology on Out-of-Plane Space-Charge Limited Hole Mobility.

PubMed

Turner, Johnathan; Gadisa, Abay

2016-12-07

Charge transport is a central issue in all types of organic electronic devices. In organic films, charge transport is crucially limited by film microstructure and the nature of the substrate/organic interface interactions. In this report, we discuss the influence of active layer thickness on space-charge limited hole transport in pristine polymer and polymer/fullerene bulk heterojunction thin films (∼15-300 nm) in a diode structure. According to the results, the out-of-plane hole mobility in pristine polymers is sensitive to the degree of polymer chain aggregation. Blending the polymers with a fullerene molecule does not change the trend of hole mobility if the polymer tends to make an amorphous structure. However, employing an aggregating polymer in a bulk heterojunction blend gives rise to a marked difference in charge carrier transport behavior compared to the pristine polymer and this difference is sensitive to active layer thickness. In aggregating polymer films, the thickness-dependent interchain interaction was found to have direct impact on hole mobility. The thickness-dependent mobility trend was found to correspond well with the trend of fill factors of corresponding bulk heterojunction solar cells. This investigation has a vital implication for material design and the development of efficient organic electronic devices, including solar cells and light-emitting diodes.

Review of NASA approach to space radiation risk assessments for Mars exploration.

PubMed

Cucinotta, Francis A

2015-02-01

Long duration space missions present unique radiation protection challenges due to the complexity of the space radiation environment, which includes high charge and energy particles and other highly ionizing radiation such as neutrons. Based on a recommendation by the National Council on Radiation Protection and Measurements, a 3% lifetime risk of exposure-induced death for cancer has been used as a basis for risk limitation by the National Aeronautics and Space Administration (NASA) for low-Earth orbit missions. NASA has developed a risk-based approach to radiation exposure limits that accounts for individual factors (age, gender, and smoking history) and assesses the uncertainties in risk estimates. New radiation quality factors with associated probability distribution functions to represent the quality factor's uncertainty have been developed based on track structure models and recent radiobiology data for high charge and energy particles. The current radiation dose limits are reviewed for spaceflight and the various qualitative and quantitative uncertainties that impact the risk of exposure-induced death estimates using the NASA Space Cancer Risk (NSCR) model. NSCR estimates of the number of "safe days" in deep space to be within exposure limits and risk estimates for a Mars exploration mission are described.

Hopf solitons in the Nicole model

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

Gillard, Mike; Sutcliffe, Paul

2010-12-15

The Nicole model is a conformal field theory in a three-dimensional space. It has topological soliton solutions classified by the integer-valued Hopf charge, and all currently known solitons are axially symmetric. A volume-preserving flow is used to construct soliton solutions numerically for all Hopf charges from 1 to 8. It is found that the known axially symmetric solutions are unstable for Hopf charges greater than 2 and new lower energy solutions are obtained that include knots and links. A comparison with the Skyrme-Faddeev model suggests many universal features, though there are some differences in the link types obtained in themore » two theories.« less

Steady-State Ion Beam Modeling with MICHELLE

NASA Astrophysics Data System (ADS)

Petillo, John

2003-10-01

There is a need to efficiently model ion beam physics for ion implantation, chemical vapor deposition, and ion thrusters. Common to all is the need for three-dimensional (3D) simulation of volumetric ion sources, ion acceleration, and optics, with the ability to model charge exchange of the ion beam with a background neutral gas. The two pieces of physics stand out as significant are the modeling of the volumetric source and charge exchange. In the MICHELLE code, the method for modeling the plasma sheath in ion sources assumes that the electron distribution function is a Maxwellian function of electrostatic potential over electron temperature. Charge exchange is the process by which a neutral background gas with a "fast" charged particle streaming through exchanges its electron with the charged particle. An efficient method for capturing this is essential, and the model presented is based on semi-empirical collision cross section functions. This appears to be the first steady-state 3D algorithm of its type to contain multiple generations of charge exchange, work with multiple species and multiple charge state beam/source particles simultaneously, take into account the self-consistent space charge effects, and track the subsequent fast neutral particles. The solution used by MICHELLE is to combine finite element analysis with particle-in-cell (PIC) methods. The basic physics model is based on the equilibrium steady-state application of the electrostatic particle-in-cell (PIC) approximation employing a conformal computational mesh. The foundation stems from the same basic model introduced in codes such as EGUN. Here, Poisson's equation is used to self-consistently include the effects of space charge on the fields, and the relativistic Lorentz equation is used to integrate the particle trajectories through those fields. The presentation will consider the complexity of modeling ion thrusters.

Methodology and Data Sources for Assessing Extreme Charging Events within the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Parker, L. N.; Minow, J. I.; Talaat, E. R.

2016-12-01

Spacecraft surface and internal charging is a potential threat to space technologies because electrostatic discharges on, or within, charged spacecraft materials can result in a number of adverse impacts to spacecraft systems. The Space Weather Action Plan (SWAP) ionizing radiation benchmark team recognized that spacecraft charging will need to be considered to complete the ionizing radiation benchmarks in order to evaluate the threat of charging to critical space infrastructure operating within the near-Earth ionizing radiation environments. However, the team chose to defer work on the lower energy charging environments and focus the initial benchmark efforts on the higher energy galactic cosmic ray, solar energetic particle, and trapped radiation belt particle environments of concern for radiation dose and single event effects in humans and hardware. Therefore, an initial set of 1 in 100 year spacecraft charging environment benchmarks remains to be defined to meet the SWAP goals. This presentation will discuss the available data sources and a methodology to assess the 1 in 100 year extreme space weather events that drive surface and internal charging threats to spacecraft. Environments to be considered are the hot plasmas in the outer magnetosphere during geomagnetic storms, relativistic electrons in the outer radiation belt, and energetic auroral electrons in low Earth orbit at high latitudes.

Effect of ion compensation of the beam space charge on gyrotron operation

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

Fokin, A. P.; Glyavin, M. Yu.; Nusinovich, G. S.

In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ionmore » compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.« less

Working Group 2 Summary:. Space Charge Effects in Bending Systems

NASA Astrophysics Data System (ADS)

Bohn, Courtlandt L.; Emma, Paul J.

2000-12-01

Participants in Working Group 2 included: Y. Batygin, C. Bohn, B. Carlsten, J. Ellison, P. Emma, Z. Huang, A. Kabel, R. Kishek, R. Li, P. Musumeci, S. Nagaitsev, J. Qiang, M. Reiser, A. Ruggerio, R. Warnock, and M. Zeitlin.

Space charge enhanced plasma gradient effects on satellite electric field measurements

NASA Technical Reports Server (NTRS)

Diebold, Dan; Hershkowitz, Noah; Dekock, J.; Intrator, T.; Hsieh, M-K.

1991-01-01

It has been recognized that plasma gradients can cause error in magnetospheric electric field measurements made by double probes. Space charge enhanced Plasma Gradient Induced Error (PGIE) is discussed in general terms, presenting the results of a laboratory experiment designed to demonstrate this error, and deriving a simple expression that quantifies this error. Experimental conditions were not identical to magnetospheric conditions, although efforts were made to insure the relevant physics applied to both cases. The experimental data demonstrate some of the possible errors in electric field measurements made by strongly emitting probes due to space charge effects in the presence of plasma gradients. Probe errors in space and laboratory conditions are discussed, as well as experimental error. In the final section, theoretical aspects are examined and an expression is derived for the maximum steady state space charge enhanced PGIE taken by two identical current biased probes.

Virtual Laboratory Environment for High Voltage Radiation Source Experiments

DTIC Science & Technology

2005-05-01

Dielectric ," Phys. Rev. Lett. 80, 103 (1998). 26.A. Valfells, J. P. Verboncoeur and Y. Y. Lau, " Space charge effects on multipactor on a dielec... effects at the edges of the surface, or due to space charge effects if a plasma is formed at the surface. High density multipactor can result in... multipactors , which can cause significant reflection and absorption of microwave power as well as space charge effects . X-rays can also

The NRL (Naval Research Laboratory) Phase-Locked Gyrotron Oscillator Program for SDIO/IST

DTIC Science & Technology

1988-07-11

are neglected as are space - charge effects . The cold cavity eigenfrequency for the TE6 2 1 mode is 35.08 GHz. The calculated efficiency, output power...improved beam quality on the gyrotron operation, and to eliminate the unknown space charge effects present in the original experiment, in which a...substantial fraction of the diode current is reflected before reaching the gyrotron cavity and may cause space charge problems before being collected on

Induction Linacs and Free Electron Laser Amplifiers

DTIC Science & Technology

1986-03-20

accelerated and the effects of space - charge force is minimized. EMnTANCE-PRESERVING BEAMLINE The beamline (Fig. 5) is designed to preserve the good beam...electrons and pushes them right out of the way leaving a bare ion cloud. With relativistic beams in vacuum, their space charge defocusing is offset by the...suspect, on why charged particle beams cannot be used in space . Now it is a fairly straight- forward extrapolation, already mentioned in Lou Marguet’s

Development of an Annular Electron Beam HPM Amplifier

DTIC Science & Technology

1994-09-01

34, Phys.Rev.Lett., 64(19), ppgs 2320-2323, 7 May 1990 9. Lau, Y.Y. and Chernin, D., "A review of the ac space - charge effect in electron-circuit interactions...the Child-Lanamuir, space - charge limiting current in the beam line. This removes the potential of torming a virtual cathode (Ref. 19). The...propagates the electron beam through a single modulating gap, with a specified voltage, frequency, and gap extent. The beam space charge is an input

Nonvolatile Memory Technology for Space Applications

NASA Technical Reports Server (NTRS)

Oldham, Timothy R.; Irom, Farokh; Friendlich, Mark; Nguyen, Duc; Kim, Hak; Berg, Melanie; LaBel, Kenneth A.

2010-01-01

This slide presentation reviews several forms of nonvolatile memory for use in space applications. The intent is to: (1) Determine inherent radiation tolerance and sensitivities, (2) Identify challenges for future radiation hardening efforts, (3) Investigate new failure modes and effects, and technology modeling programs. Testing includes total dose, single event (proton, laser, heavy ion), and proton damage (where appropriate). Test vehicles are expected to be a variety of non-volatile memory devices as available including Flash (NAND and NOR), Charge Trap, Nanocrystal Flash, Magnetic Memory (MRAM), Phase Change--Chalcogenide, (CRAM), Ferroelectric (FRAM), CNT, and Resistive RAM.

1989 IEEE Annual Conference on Nuclear and Space Radiation Effects, 26th, Marco Island, FL, July 25-29, 1989, Proceedings. Part 1

NASA Technical Reports Server (NTRS)

Ochoa, Agustin, Jr. (Editor)

1989-01-01

Various papers on nuclear science are presented. The general topics addressed include: basic mechanics of radiation effects, dosimetry and energy-dependent effects, hardness assurance and testing techniques, spacecraft charging and space radiation effects, EMP/SGEMP/IEMP phenomena, device radiation effects and hardening, radiation effects on isolation technologies, IC radiation effects and hardening, and single-event phenomena.

The aerodynamics of bodies in a rarefied ionized gas with applications to spacecraft environmental dynamics

NASA Technical Reports Server (NTRS)

Stone, N. H.

1981-01-01

The objectives are to provide a parametric description of the electrostatic interaction of a mesosonic, collisionless plasma with conducting bodies on the order of 1 to 10 Debye lengths in size, and to extend this description to the satellite-ionospheric interaction, where possible. Experimental findings include: the wake of the geometrically complex body appears to be a linear superposition of the wakes of its simple geometric components; and vector ion flux measurements show converging ion streams at the wake axis and direct evidence of ion streams deflected from the wake axis by the positive space charge potential associated with the axial ion peak. The extension to the satellite-ionospheric interaction utilizes qualitative scaling and indicates that similar, but smaller amplitude, wake structures may be expected for small or highly charged bodies. However, for large bodies at small potentials, the structure may be diffused by the thermal ion motion and the dispersion resulting for space charge potentials.

High-temperature superconductivity in space-charge regions of lanthanum cuprate induced by two-dimensional doping

PubMed Central

Baiutti, F.; Logvenov, G.; Gregori, G.; Cristiani, G.; Wang, Y.; Sigle, W.; van Aken, P. A.; Maier, J.

2015-01-01

The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field. PMID:26481902

A versatile detector system to measure the change states, mass compositions and energy spectra of interplanetary and magnetosphere ions

NASA Technical Reports Server (NTRS)

Gloeckler, G.

1977-01-01

An instrument is described for measuring the mass and charge state composition as well as the energy spectra and angular distributions of 0.5 to 350 kev/charge ions in interplanetary space and in magnetospheres of planets such as Jupiter and earth. Electrostatic deflection combined with a time-of-flight and energy measurement allows three-parameter analysis of output signals from which the mass, charge states, and energy are determined. Post-acceleration by 30 kV extends the energy range of the detector system into the solar wind and magnetosphere plasma regime. Isotopes of H and He are easily resolved as are individual elements up to Ne and the dominant elements up to and including Fe. This instrument has an extremely large dynamic range in intensity and is sensitive to rare elements even in the presence of high intensity radiation, and is adapted for interplanetary, deep-space, and out-of-the-ecliptic missions, as well as for flights on spacecraft orbiting Jupiter and earth.

Beam dynamics performances and applications of a low-energy electron-beam magnetic bunch compressor

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

Prokop, C. R.; Piot, P.; Carlsten, B. E.

2013-08-01

Many front-end applications of electron linear accelerators rely on the production of temporally compressed bunches. The shortening of electron bunches is often realized with magnetic bunch compressors located in high-energy sections of accelerators. Magnetic compression is subject to collective effects including space charge and self interaction via coherent synchrotron radiation. In this paper we explore the application of magnetic compression to low-energy (~40MeV), high-charge (nC) electron bunches with low normalized transverse emittances (<5@mm).

Determination of the space-charge field amplitude in polymeric photorefractive polymers.

PubMed

Hwang, Ui-Jung; Choi, Chil-Sung; Vuong, Nguyen Quoc; Kim, Nakjoong

2005-12-22

The space-charge field built in a polymeric photorefractive polymer was calculated by a simple method based on the oriented gas model. When anisotropic chromophores in a photorefractive polymer were exposed to an external field, they oriented preferentially to exhibit a birefringence. Then, under illumination of two coherent beams and an external field, they reoriented to form a photorefractive grating. During the formation of the grating, the chromophores were reoriented by the space-charge field as well as by the external applied field. The birefringence induced in the material by an external electric field was determined by measuring the transmittance of the sample which is placed between crossed polarizers, where birefringence depicts the orientation of the chromophores. By measuring the diffraction efficiency with a modified degenerate four-wave mixing setup, the index amplitude of the grating was determined. Finally, the space-charge field was determined by comparing the diffraction efficiency with the birefringence with respect to the applied electric field. In our study, the space-charge field was about 20% of the external applied field, which coincided with previous results obtained from our laboratory.

Study of electric field distorted by space charges under positive lightning impulse voltage

NASA Astrophysics Data System (ADS)

Wang, Zezhong; Geng, Yinan

2018-03-01

Actually, many insulation problems are related to electric fields. And measuring electric fields is an important research topic of high-voltage engineering. In particular, the electric field distortion caused by space charge is the basis of streamer theory, and thus quantitatively measuring the Poisson electric field caused by space charge is significant to researching the mechanism of air gap discharge. In this paper, we used our photoelectric integrated sensor to measure the electric field distribution in a 1-m rod-plane gap under positive lightning impulse voltage. To verify the reliability of this quantitative measurement, we compared the measured results with calculated results from a numerical simulation. The electric-field time domain waveforms on the axis of the 1-m rod-plane out of the space charge zone were measured with various electrodes. The Poisson electric fields generated by space charge were separated from the Laplace electric field generated by applied voltages, and the amplitudes and variations were measured for various applied voltages and at various locations. This work also supplies the feasible basis for directly measuring strong electric field under high voltage.

Space Environment Effects on Materials : An Overview

NASA Technical Reports Server (NTRS)

Garrett, Henry B.

2006-01-01

A general overview on the space environment and its effects on materials is presented. The topics include: 1) Impact of Space Effects on Spacecraft Costs; 2) Space Environment Effects on Spacecraft by Source; 3) Primary Source of Space Effects: The Sun; 4) The Earth's Environment; 5) Trapped Radiation Belts; 6) Aurora Are Everywhere; 7) Spacecraft Interactions; 8) Atmospheric Effects; 9) Contaminant Effects on Materials; 10) Meteoroid/Debris Effects on Materials; 11) Spacecraft Surface Charging; 12) Surface Discharge Effects; 13) Internal Electrostatic Discharge--Satellite Killer; 14) Plasma Interactions DS-1 Ion Engines; 15) Radiation Effects on Spacecraft Systems and Materials; 16) Total Ionizing Dose Effects Total Ionizing Dose Effects; 17) Man-Made Sources of Space Effects Man-Made Sources of Space Effects; and 18) Space Environments Versus Interactions.

Indirect Charged Particle Detection: Concepts and a Classroom Demonstration

ERIC Educational Resources Information Center

Childs, Nicholas B.; Horányi, Mihály; Collette, Andrew

2013-01-01

We describe the principles of macroscopic charged particle detection in the laboratory and their connections to concepts taught in the physics classroom. Electrostatic dust accelerator systems, capable of launching charged dust grains at hypervelocities (1-100 km/s), are a critical tool for space exploration. Dust grains in space typically have…

Asymptotic symmetries of Rindler space at the horizon and null infinity

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

Chung, Hyeyoun

2010-08-15

We investigate the asymptotic symmetries of Rindler space at null infinity and at the event horizon using both systematic and ad hoc methods. We find that the approaches that yield infinite-dimensional asymptotic symmetry algebras in the case of anti-de Sitter and flat spaces only give a finite-dimensional algebra for Rindler space at null infinity. We calculate the charges corresponding to these symmetries and confirm that they are finite, conserved, and integrable, and that the algebra of charges gives a representation of the asymptotic symmetry algebra. We also use relaxed boundary conditions to find infinite-dimensional asymptotic symmetry algebras for Rindler spacemore » at null infinity and at the event horizon. We compute the charges corresponding to these symmetries and confirm that they are finite and integrable. We also determine sufficient conditions for the charges to be conserved on-shell, and for the charge algebra to give a representation of the asymptotic symmetry algebra. In all cases, we find that the central extension of the charge algebra is trivial.« less

Numerical study on electronic and optical properties of organic light emitting diodes.

PubMed

Kim, Kwangsik; Hwang, Youngwook; Won, Taeyoung

2013-08-01

In this paper, we present a finite element method (FEM) study of space charge effects in organic light emitting diodes. Our model includes a Gaussian density of states to account for the energetic disorder in organic semiconductors and the Fermi-Dirac statistics to account for the charge hopping process between uncorrelated sites. The physical model cover all the key physical processes in OLEDs, namely charge injection, transport and recombination, exciton diffusion, transfer and decay as well as light coupling, and thin-film-optics. The exciton model includes generation, diffusion, and energy transfer as well as annihilation. We assumed that the light emission originates from oscillating and thus embodied as excitons and embedded in a stack of multilayer. The out-coupled emission spectrum has been numerically calculated as a function of viewing angle, polarization, and dipole orientation. We discuss the accumulation of charges at internal interfaces and their signature in the transient response as well as the electric field distribution.

Space charge effects in ultrafast electron diffraction and imaging

NASA Astrophysics Data System (ADS)

Tao, Zhensheng; Zhang, He; Duxbury, P. M.; Berz, Martin; Ruan, Chong-Yu

2012-02-01

Understanding space charge effects is central for the development of high-brightness ultrafast electron diffraction and microscopy techniques for imaging material transformation with atomic scale detail at the fs to ps timescales. We present methods and results for direct ultrafast photoelectron beam characterization employing a shadow projection imaging technique to investigate the generation of ultrafast, non-uniform, intense photoelectron pulses in a dc photo-gun geometry. Combined with N-particle simulations and an analytical Gaussian model, we elucidate three essential space-charge-led features: the pulse lengthening following a power-law scaling, the broadening of the initial energy distribution, and the virtual cathode threshold. The impacts of these space charge effects on the performance of the next generation high-brightness ultrafast electron diffraction and imaging systems are evaluated.

Electrostatic Studies for the 2008 Hubble Service Repair Mission

NASA Technical Reports Server (NTRS)

Buhler, C. R.; Clements, J. S.; Calle, C. I.

2012-01-01

High vacuum triboelectric testing of space materials was required to identify possible Electrostatic Discharge (ESD) concerns for the astronauts in space during electronics board replacement on the Hubble Space Telescope. Testing under high vacuum conditions with common materials resulted in some interesting results. Many materials were able to charge to high levels which did not dissipate quickly even when grounded. Certain materials were able to charge up in contact with grounded metals while others were not. An interesting result was that like materials did not exchange electrostatic charge under high vacuum conditions. The most surprising experimental result is the lack of brush discharges from charged insulators under high vacuum conditions.

Space charge neutralization by electron-transparent suspended graphene

PubMed Central

Srisonphan, Siwapon; Kim, Myungji; Kim, Hong Koo

2014-01-01

Graphene possesses many fascinating properties originating from the manifold potential for interactions at electronic, atomic, or molecular levels. Here we report measurement of electron transparency and hole charge induction response of a suspended graphene anode on top of a void channel formed in a SiO2/Si substrate. A two-dimensional (2D) electron gas induced at the oxide interface emits into air and makes a ballistic transport toward the suspended graphene. A small fraction (>~0.1%) of impinging electrons are captured at the edge of 2D hole system in graphene, demonstrating good transparency to very low energy (<3 eV) electrons. The hole charges induced in the suspended graphene anode have the effect of neutralizing the electron space charge in the void channel. This charge compensation dramatically enhances 2D electron gas emission at cathode to the level far surpassing the Child-Langmuir's space-charge-limited emission. PMID:24441774

Opportunities for Utilizing the International Space Station for Studies of F2- Region Plasma Science and High Voltage Solar Array Interactions with the Plasma Environment

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Coffey, Victoria; Wright, Kenneth; Craven, Paul; Koontz, Steven

2010-01-01

The near circular, 51.6deg inclination orbit of the International Space Station (ISS) is maintained within an altitude range of approximately 300 km to 400 km providing an ideal platform for conducting in-situ studies of space weather effects on the mid and low-latitude F-2 region ionosphere. The Floating Potential Measurement Unit (FPMU) is a suite of instruments installed on the ISS in August 2006 which includes a Floating Potential Probe (FPP), a Plasma Impedance Probe (PIP), a Wide-sweep Langmuir Probe (WLP), and a Narrow-sweep Langmuir Probe (NLP). The primary purpose for deploying the FPMU is to characterize ambient plasma temperatures and densities in which the ISS operates and to obtain measurements of the ISS potential relative to the space plasma environment for use in characterizing and mitigating spacecraft charging hazards to the vehicle and crew. In addition to the engineering goals, data from the FPMU instrument package is available for collaborative multi-satellite and ground based instrument studies of the F-region ionosphere during both quiet and disturbed periods. Finally, the FPMU measurements supported by ISS engineering telemetry data provides a unique opportunity to investigate interactions of the ISS high voltage (160 volt) solar array system with the plasma environment. This presentation will provide examples of FPMU measurements along the ISS orbit including night-time equatorial plasma density depletions sampled near the peak electron density in the F2-region ionosphere, charging phenomenon due to interaction of the ISS solar arrays with the plasma environment, and modification of ISS charging due to visiting vehicles demonstrating the capabilities of the FPMU probes for monitoring mid and low latitude plasma processes as well as vehicle interactions with the plasma environment.

Studies of dynamic processes related to active experiments in space plasmas

NASA Technical Reports Server (NTRS)

Banks, Peter M.; Neubert, Torsten

1992-01-01

This is the final report for grant NAGw-2055, 'Studies of Dynamic Processes Related to Active Experiments in Space Plasmas', covering research performed at the University of Michigan. The grant was awarded to study: (1) theoretical and data analysis of data from the CHARGE-2 rocket experiment (1keV; 1-46 mA electron beam ejections) and the Spacelab-2 shuttle experiment (1keV; 100 mA); (2) studies of the interaction of an electron beam, emitted from an ionospheric platform, with the ambient neutral atmosphere and plasma by means of a newly developed computer simulation model, relating model predictions with CHARGE-2 observations of return currents observed during electron beam emissions; and (3) development of a self-consistent model for the charge distribution on a moving conducting tether in a magnetized plasma and for the potential structure in the plasma surrounding the tether. Our main results include: (1) the computer code developed for the interaction of electrons beams with the neutral atmosphere and plasma is able to model observed return fluxes to the CHARGE-2 sounding rocket payload; and (2) a 3-D electromagnetic and relativistic particle simulation code was developed.

Numerical quasi-linear study of the critical ionization velocity phenomenon

NASA Technical Reports Server (NTRS)

Moghaddam-Taaheri, E.; Goertz, C. K.

1993-01-01

The critical ionization velocity (CIV) for a neutral barium (Ba) gas cloud moving across the static magnetic field is studied numerically using quasi-linear equations and a parameter range which is typical for the shaped-charge Ba gas release experiments in space. For consistency the charge exchange between the background oxygen ions and neutral atoms and its reverse process, as well as the excitation of the neutral Ba atoms, are included. The numerical results indicate that when the ionization rate due to CIV becomes comparable to the charge exchange rate the energy lost to the ionization and excitation collisions by the superthermal electrons exceeds the energy gain from the waves that are excited by the ion beam. This results in a CIV yield less than the yield by the charge exchange process.

An Analysis of High-Power Radar TR-Limited with Very Short Recovery Time,

DTIC Science & Technology

1981-05-07

field in the gap will continuously grow stronger, until the space charge field cancels the accelerating effect of 19 the high frequency field on the...weak in the middle. 29 .,.a1 ,-t *’:.--’ ’ - - Clearly the space charge field has a repelling effect on the secondary electrons emitted by electrode...homogeneous. Therefore, the bias value in the space charge field induces an effect on the kinetic state of the electronic dissipation process. This is small

Experimental and Theoretical Investigations of Charged Phospholipid Bilayers.

NASA Astrophysics Data System (ADS)

Graham, Ian Stanley

1987-09-01

Lipid systems containing charged species are examined by both experiment and theory. Experimental studies of the mixing of phosphatidylcholine or phosphatidylethanolamine with phosphatidic acid show that calcium induces fast ( <=q1s) phase separation of these otherwise miscible systems, and that this can occur in an isolated bilayer. Ionogenic behaviour is theoretically investigated using a new electrolyte model which explicitly includes both the solvent and particle sizes, and a binding model which uses Guggenheim combinatorics to treat non 1-1 binding stoichiometries. This work predicts a reduced dielectric constant near charged surfaces and strong repulsive forces between closely spaced (<15A) surfaces. A reanalysis of data from charged monolayers experiments indicates (1) that the new electrolyte model describes double layer behaviour at high surface charge densities better than the traditional Derjaguin - Landau - Verwey - Overbeek (DLVO) theory, (2) that calcium and magnesium bind to phosphatidylserine monolayers with a 1-1 stoichiometry.

Understanding the Thickness-Dependent Performance of Organic Bulk Heterojunction Solar Cells: The Influence of Mobility, Lifetime, and Space Charge.

PubMed

Kirchartz, Thomas; Agostinelli, Tiziano; Campoy-Quiles, Mariano; Gong, Wei; Nelson, Jenny

2012-12-06

We investigate the reasons for the dependence of photovoltaic performance on the absorber thickness of organic solar cells using experiments and drift-diffusion simulations. The main trend in photocurrent and fill factor versus thickness is determined by mobility and lifetime of the charge carriers. In addition, space charge becomes more and more important the thicker the device is because it creates field free regions with low collection efficiency. The two main sources of space-charge effects are doping and asymmetric mobilities. We show that for our experimental results on Si-PCPDTBT:PC71BM (poly[(4,40-bis(2-ethylhexyl)dithieno[3,2-b:20,30-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,50-diyl]:[6,6]-phenyl C71-butyric acid methyl ester) solar cells, the influence of doping is most likely the dominant influence on the space charge and has an important effect on the thickness dependence of performance.

Longitudinal bunch shaping of picosecond high-charge MeV electron beams

DOE PAGES

Beaudoin, B. L.; Thangaraj, J. C. T.; Edstrom, Jr., D.; ...

2016-10-20

With ever increasing demands for intensities in modern accelerators, the understanding of space-charge effects becomes crucial. Herein are presented measurements of optically shaped picosecond-long electron beams in a superconducting L-band linac over a wide range of charges, from 0.2 nC to 3.4 nC. At low charges, the shape of the electron beam is preserved, while at higher charge densities, modulations on the beam convert to energy modulations. Here, energy profile measurements using a spectrometer and time profile measurements using a streak camera reveal the dynamics of longitudinal space-charge on MeV-scale electron beams.

Validation of the NASCAP model using spaceflight data

NASA Technical Reports Server (NTRS)

Stannard, P. R.; Katz, I.; Gedeon, L.; Roche, J. C.; Rubin, A. G.; Tautz, M. F.

1982-01-01

The NASA Charging Analyzer Program (NASCAP) has been validated in a space environment. Data collected by the SCATHA (Spacecraft Charging at High Altitude) spacecraft has been used with NASCAP to simulate the charging response of the spacecraft ground conductor and dielectric surfaces with considerable success. Charging of the spacecraft ground observed in eclipse, during moderate and severe substorm environments, and in sunlight has been reproduced using the code. Close agreement between both the currents and potentials measured by the SSPM's, and the NASCAP simulated response, has been obtained for differential charging. It is concluded that NASCAP is able to predict spacecraft charging behavior in a space environment.

Over-injection and self-oscillations in an electron vacuum diode

NASA Astrophysics Data System (ADS)

Leopold, J. G.; Siman-Tov, M.; Goldman, A.; Krasik, Ya. E.

2017-07-01

We demonstrate a practical means by which one can inject more than the space-charge limiting current into a vacuum diode. This over-injection causes self-oscillations of the space-charge resulting in an electron beam current modulation at a fixed frequency, a reaction of the system to the Coulomb repulsive forces due to charge accumulation.

1988 IEEE Annual Conference on Nuclear and Space Radiation Effects, 25th, Portland, OR, July 12-15, 1988, Proceedings

NASA Technical Reports Server (NTRS)

Coakley, Peter G. (Editor)

1988-01-01

The effects of nuclear and space radiation on the performance of electronic devices are discussed in reviews and reports of recent investigations. Topics addressed include the basic mechanisms of radiation effects, dosimetry and energy-dependent effects, sensors in and for radiation environments, EMP/SGEMP/IEMP phenomena, radiation effects on isolation technologies, and spacecraft charging and space radiation effects. Consideration is given to device radiation effects and hardening, hardness assurance and testing techniques, IC radiation effects and hardening, and single-event phenomena.

Charge Transport in Spiro-OMeTAD Investigated through Space-Charge-Limited Current Measurements

NASA Astrophysics Data System (ADS)

Röhr, Jason A.; Shi, Xingyuan; Haque, Saif A.; Kirchartz, Thomas; Nelson, Jenny

2018-04-01

Extracting charge-carrier mobilities for organic semiconductors from space-charge-limited conduction measurements is complicated in practice by nonideal factors such as trapping in defects and injection barriers. Here, we show that by allowing the bandlike charge-carrier mobility, trap characteristics, injection barrier heights, and the shunt resistance to vary in a multiple-trapping drift-diffusion model, a numerical fit can be obtained to the entire current density-voltage curve from experimental space-charge-limited current measurements on both symmetric and asymmetric 2 ,2',7 ,7' -tetrakis(N ,N -di-4-methoxyphenylamine)-9 ,9' -spirobifluorene (spiro-OMeTAD) single-carrier devices. This approach yields a bandlike mobility that is more than an order of magnitude higher than the effective mobility obtained using analytical approximations, such as the Mott-Gurney law and the moving-electrode equation. It is also shown that where these analytical approximations require a temperature-dependent effective mobility to achieve fits, the numerical model can yield a temperature-, electric-field-, and charge-carrier-density-independent mobility. Finally, we present an analytical model describing trap-limited current flow through a semiconductor in a symmetric single-carrier device. We compare the obtained charge-carrier mobility and trap characteristics from this analytical model to the results from the numerical model, showing excellent agreement. This work shows the importance of accounting for traps and injection barriers explicitly when analyzing current density-voltage curves from space-charge-limited current measurements.

Particle accelerator employing transient space charge potentials

DOEpatents

Post, Richard F.

1990-01-01

The invention provides an accelerator for ions and charged particles. The plasma is generated and confined in a magnetic mirror field. The electrons of the plasma are heated to high temperatures. A series of local coils are placed along the axis of the magnetic mirror field. As an ion or particle beam is directed along the axis in sequence the coils are rapidly pulsed creating a space charge to accelerate and focus the beam of ions or charged particles.

Surface charge- and space-dependent transport of proteins in crowded environments of nanotailored posts.

PubMed

Choi, Chang Kyoung; Fowlkes, Jason D; Retterer, Scott T; Siuti, Piro; Iyer, Sukanya; Doktycz, Mitchel J

2010-06-22

The reaction and diffusion of molecules across barriers and through crowded environments is integral to biological system function and to separation technologies. Ordered, microfabricated post arrays are a promising route to creating synthetic barriers with controlled chemical and physical characteristics. They can be used to create crowded environments, to mimic aspects of cellular membranes, and to serve as engineered replacements of polymer-based separation media. Here, the translational diffusion of fluorescein isothiocyante and various forms of green fluorescent protein (GFP), including "supercharged" variants, are examined in a silicon-based post array environment. The technique of fluorescence recovery after photobleaching (FRAP) is combined with analytical approximations and numerical simulations to assess the relative effects of reaction and diffusion on molecular transport, respectively. FRAP experiments were conducted for 64 different cases where the molecular species, the density of the posts, and the chemical surface charge of the posts were varied. In all cases, the dense packing of the posts hindered the diffusive transport of the fluorescent species. The supercharged GFPs strongly interacted with oppositely charged surfaces. With similar molecular and surface charges, transport is primarily limited by hindered diffusion. For conventional, enhanced GFP in a positively charged surface environment, transport was limited by the coupled action of hindered diffusion and surface interaction with the posts. Quantification of the size-, space-, time-, and charge-dependent translational diffusion in the post array environments can provide insight into natural processes and guide the design and development of selective membrane systems.

Annual Conference on Nuclear and Space Radiation Effects, Gatlinburg, TN, July 18-21, 1983, Proceedings

NASA Technical Reports Server (NTRS)

1983-01-01

Topics discussed include radiation effects in devices; the basic mechanisms of radiation effects in structures and materials; radiation effects in integrated circuits; spacecraft charging and space radiation effects; hardness assurance for devices and systems; and radiation transport, energy deposition and charge collection. Papers are presented on the mechanisms of small instabilities in irradiated MOS transistors, on the radiation effects on oxynitride gate dielectrics, on the discharge characteristics of a simulated solar cell array, and on latchup in CMOS devices from heavy ions. Attention is also given to proton upsets in orbit, to the modeling of single-event upset in bipolar integrated circuits, to high-resolution studies of the electrical breakdown of soil, and to a finite-difference solution of Maxwell's equations in generalized nonorthogonal coordinates.

Spacecraft Charging Standard Report.

DTIC Science & Technology

1980-09-30

SSPM include: SAMPLE POTENTIAL (with respect to S/C ground) Aluminized Kapton -2.0 kV Silvered Teflon -4.0 kV Astroquartz -3.7 kV 50.3 Analysis. As...and potential gradients on the space vehicle (candidate spacecraft locations for ESD tests) (The NASCAP computer code, when validated, will be useful...The coupling analysis should then determine as a minimum: I. electromagnetic fields generated interior to the space vehicle due to ESD 2. induced

I-V-T analysis of radiation damage in high efficiency Si solar cells

NASA Technical Reports Server (NTRS)

Banerjee, S.; Anderson, W. A.; Rao, B. B.

1985-01-01

A detailed analysis of current-voltage characteristics of N(+)-P/P solar cells indicate that there is a combination of different mechanisms which results in an enhancement in the dark current and in turn deteriorates the photovoltaic performance of the solar cells after 1 MeV e(-) irradiation. The increase in the dark current is due to three effects, i.e., bulk recombination, space charge recombination by deep traps and space charge recombination through shallow traps. It is shown that the increase in bulk recombination current is about 2 to 3 orders of magnitude whereas space charge recombination current due to shallow traps increases only by an order or so and no space charge recombination through deep traps was observed after irradiation. Thus, in order to improve the radiation hardness of these devices, bulk properties should be preserved.

Spinor Structure and Internal Symmetries

NASA Astrophysics Data System (ADS)

Varlamov, V. V.

2015-10-01

Spinor structure and internal symmetries are considered within one theoretical framework based on the generalized spin and abstract Hilbert space. Complex momentum is understood as a generating kernel of the underlying spinor structure. It is shown that tensor products of biquaternion algebras are associated with the each irreducible representation of the Lorentz group. Space-time discrete symmetries P, T and their combination PT are generated by the fundamental automorphisms of this algebraic background (Clifford algebras). Charge conjugation C is presented by a pseudoautomorphism of the complex Clifford algebra. This description of the operation C allows one to distinguish charged and neutral particles including particle-antiparticle interchange and truly neutral particles. Spin and charge multiplets, based on the interlocking representations of the Lorentz group, are introduced. A central point of the work is a correspondence between Wigner definition of elementary particle as an irreducible representation of the Poincaré group and SU(3)-description (quark scheme) of the particle as a vector of the supermultiplet (irreducible representation of SU(3)). This correspondence is realized on the ground of a spin-charge Hilbert space. Basic hadron supermultiplets of SU(3)-theory (baryon octet and two meson octets) are studied in this framework. It is shown that quark phenomenologies are naturally incorporated into presented scheme. The relationship between mass and spin is established. The introduced spin-mass formula and its combination with Gell-Mann-Okubo mass formula allows one to take a new look at the problem of mass spectrum of elementary particles.

Recent Applications of Space Weather Research to NASA Space Missions

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Howard, James W., Jr.; Miller, J. Scott; Minow, Joseph I.; NeergardParker, L.; Suggs, Robert M.

2013-01-01

Marshall Space Flight Center s Space Environments Team is committed to applying the latest research in space weather to NASA programs. We analyze data from an extensive set of space weather satellites in order to define the space environments for some of NASA s highest profile programs. Our goal is to ensure that spacecraft are designed to be successful in all environments encountered during their missions. We also collaborate with universities, industry, and other federal agencies to provide analysis of anomalies and operational impacts to current missions. This presentation is a summary of some of our most recent applications of space weather data, including the definition of the space environments for the initial phases of the Space Launch System (SLS), acquisition of International Space Station (ISS) frame potential variations during geomagnetic storms, and Nascap-2K charging analyses.

Comparison between field mill and corona point instrumentation at Kennedy Space Center - Use of these data with a model to determine cloudbase electric fields

NASA Technical Reports Server (NTRS)

Markson, R.; Anderson, B.; Govaert, J.; Fairall, C. W.

1989-01-01

A novel coronal current-determining instrument is being used at NASA-KSC which overcomes previous difficulties with wind sensitivity and a voltage-threshold 'deadband'. The mounting of the corona needle at an elevated location reduces coronal and electrode layer space-charge influences on electric fields, rendering the measurement of space charge density possible. In conjunction with a space-charge compensation model, these features allow a more realistic estimation of cloud base electric fields and the potential for lightning strike than has previously been possible with ground-based sensors.

Charged-particle emission tomography

NASA Astrophysics Data System (ADS)

Ding, Yijun

Conventional charged-particle imaging techniques--such as autoradiography-- provide only two-dimensional (2D) images of thin tissue slices. To get volumetric information, images of multiple thin slices are stacked. This process is time consuming and prone to distortions, as registration of 2D images is required. We propose a direct three-dimensional (3D) autoradiography technique, which we call charged-particle emission tomography (CPET). This 3D imaging technique enables imaging of thick sections, thus increasing laboratory throughput and eliminating distortions due to registration. In CPET, molecules or cells of interest are labeled so that they emit charged particles without significant alteration of their biological function. Therefore, by imaging the source of the charged particles, one can gain information about the distribution of the molecules or cells of interest. Two special case of CPET include beta emission tomography (BET) and alpha emission tomography (alphaET), where the charged particles employed are fast electrons and alpha particles, respectively. A crucial component of CPET is the charged-particle detector. Conventional charged-particle detectors are sensitive only to the 2-D positions of the detected particles. We propose a new detector concept, which we call particle-processing detector (PPD). A PPD measures attributes of each detected particle, including location, direction of propagation, and/or the energy deposited in the detector. Reconstruction algorithms for CPET are developed, and reconstruction results from simulated data are presented for both BET and alphaET. The results show that, in addition to position, direction and energy provide valuable information for 3D reconstruction of CPET. Several designs of particle-processing detectors are described. Experimental results for one detector are discussed. With appropriate detector design and careful data analysis, it is possible to measure direction and energy, as well as position of each detected particle. The null functions of CPET with PPDs that measure different combinations of attributes are calculated through singular-value decomposition. In general, the more particle attributes are measured from each detection event, the smaller the null space of CPET is. In other words, the higher dimension the data space is, the more information about an object can be recovered from CPET.

46 CFR 525.1 - Purpose and scope.

Code of Federal Regulations, 2014 CFR

2014-10-01

... MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE MARINE TERMINAL OPERATOR... terminal schedule during which cargo may occupy space assigned to it on terminal property, including off... usages, customs or modes of operation which in any way affect, determine or change the rates, charges or...

46 CFR 525.1 - Purpose and scope.

Code of Federal Regulations, 2011 CFR

2011-10-01

... MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE MARINE TERMINAL OPERATOR... terminal schedule during which cargo may occupy space assigned to it on terminal property, including off... usages, customs or modes of operation which in any way affect, determine or change the rates, charges or...

46 CFR 525.1 - Purpose and scope.

Code of Federal Regulations, 2013 CFR

2013-10-01

... MARITIME COMMISSION REGULATIONS AFFECTING OCEAN SHIPPING IN FOREIGN COMMERCE MARINE TERMINAL OPERATOR... terminal schedule during which cargo may occupy space assigned to it on terminal property, including off... usages, customs or modes of operation which in any way affect, determine or change the rates, charges or...

41 CFR 102-79.45 - What type of services may Federal agencies provide without charge to Federal credit unions?

Code of Federal Regulations, 2010 CFR

2010-07-01

... other expenses associated with telephone service); and (g) Security systems (including installation and other expenses associated with security systems). Utilization of Space ... Public Contracts and Property Management Federal Property Management Regulations System (Continued...

Electromagnetic Interference Behavior of Multiwall Carbon Nanotubes and Carbon Nanofibers Composites Under Fatigue

DTIC Science & Technology

2012-03-01

introducing conductive metallic materials onto or into the polymer composite. The earlier process steps included metallic paint coating, insertion......onboard from critical data loss to permanent damage. The ionized radiation strips electrons from atoms in the space plasma, creating charged

Stochastic approach and fluctuation theorem for charge transport in diodes

NASA Astrophysics Data System (ADS)

Gu, Jiayin; Gaspard, Pierre

2018-05-01

A stochastic approach for charge transport in diodes is developed in consistency with the laws of electricity, thermodynamics, and microreversibility. In this approach, the electron and hole densities are ruled by diffusion-reaction stochastic partial differential equations and the electric field generated by the charges is determined with the Poisson equation. These equations are discretized in space for the numerical simulations of the mean density profiles, the mean electric potential, and the current-voltage characteristics. Moreover, the full counting statistics of the carrier current and the measured total current including the contribution of the displacement current are investigated. On the basis of local detailed balance, the fluctuation theorem is shown to hold for both currents.

Comparison of Detector Technologies for CAPS

NASA Technical Reports Server (NTRS)

Stockum, Jana L.

2005-01-01

In this paper, several different detectors are examined for use in a Comet/Asteroid Protection System (CAPS), a conceptual study for a possible future space-based system. Each detector will be examined for its future (25 years or more in the future) ability to find and track near-Earth Objects (NEOs) from a space-based detection platform. Within the CAPS study are several teams of people who each focus on different aspects of the system concept. This study s focus is on detection devices. In particular, evaluations on the following devices have been made: charge-coupled devices (CCDs), charge-injected devices (CIDs), superconducting tunneling junctions (STJs), and transition edge sensors (TESs). These devices can be separated into two main categories; the first category includes detectors that are currently being widely utilized, such as CCDs and CIDs. The second category includes experimental detectors, such as STJs and TESs. After the discussion of the detectors themselves, there will be a section devoted to the explicit use of these detectors with CAPS.

Measurements of Ionospheric Density, Temperature, and Spacecraft Charging in a Space Weather Constellation

NASA Astrophysics Data System (ADS)

Balthazor, R. L.; McHarg, M. G.; Wilson, G.

2016-12-01

The Integrated Miniaturized Electrostatic Analyzer (IMESA) is a space weather sensor developed by the United States Air Force Academy and integrated and flown by the DoD's Space Test Program. IMESA records plasma spectrograms from which can be derived plasma density, temperature, and spacecraft frame charging. Results from IMESA currently orbiting on STPSat-3 are presented, showing frame charging effects dependent on a complex function of the number of solar panel cell strings switched in, solar panel current, and plasma density. IMESA will fly on four more satellites launching in the next two calendar years, enabling an undergraduate DoD space weather constellation in Low Earth Orbit that has the ability to significantly improve space weather forecasting capabilities using assimilative forecast models.

Correlation of ISS Electric Potential Variations with Mission Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda Neergaard

2014-01-01

Orbiting approximately 400 km above the Earth, the International Space Station (ISS) is a unique research laboratory used to conduct ground-breaking science experiments in space. The ISS has eight Solar Array Wings (SAW), and each wing is 11.7 meters wide and 35.1 meters long. The SAWs are controlled individually to maximize power output, minimize stress to the ISS structure, and minimize interference with other ISS operations such as vehicle dockings and Extra-Vehicular Activities (EVA). The Solar Arrays are designed to operate at 160 Volts. These large, high power solar arrays are negatively grounded to the ISS and collect charged particles (predominately electrons) as they travel through the space plasma in the Earth's ionosphere. If not controlled, this collected charge causes floating potential variations which can result in arcing, causing injury to the crew during an EVA or damage to hardware [1]. The environmental catalysts for ISS floating potential variations include plasma density and temperature fluctuations and magnetic induction from the Earth's magnetic field. These alone are not enough to cause concern for ISS, but when they are coupled with the large positive potential on the solar arrays, floating potentials up to negative 95 Volts have been observed. Our goal is to differentiate the operationally induced fluctuations in floating potentials from the environmental causes. Differentiating will help to determine what charging can be controlled, and we can then design the proper operations controls for charge collection mitigation. Additionally, the knowledge of how high power solar arrays interact with the environment and what regulations or design techniques can be employed to minimize charging impacts can be applied to future programs.

The End of Free Space

ERIC Educational Resources Information Center

Carlson, Scott

2012-01-01

The author reports on the reigning economic calculus that helps to drive constant expansion and poor utilization of space on many campuses. The author states that colleges could charge for utilities, which might encourage departments to save energy. Most American colleges do not charge for space--in part because doing so would raise the hackles of…

14 CFR Appendix B to Part 1215 - Factors Affecting Standard Charges

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Factors Affecting Standard Charges B Appendix B to Part 1215 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TRACKING AND DATA RELAY SATELLITE SYSTEM (TDRSS) Pt. 1215, App. B Appendix B to Part 1215—Factors Affecting Standard...

Dielectric properties and effect of electrical aging on space charge accumulation in polyimide/TiO2 nanocomposite films

NASA Astrophysics Data System (ADS)

Zha, Jun-Wei; Dang, Zhi-Min; Song, Hong-Tao; Yin, Yi; Chen, George

2010-11-01

In situ polymerized polyimide/TiO2 (PI/TiO2) nanocomposite films with good electrical aging resistance are studied. Space charge distribution in the PI/TiO2 nanocomposite films are measured using the pulsed electroacoustic method. Dielectric properties of the films are measured in the frequency range of 102 Hz-106 Hz by an impedance analyzer (Agilent 4294A) at room temperature. These nanocomposite films are also characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). It is demonstrated that the nano-TiO2 particles strongly affect dielectric breakdown, lifetime and space charge distribution, and increase the voltage endurance of the nanocomposite films significantly. SEM analyses show that the nanocomposite films are destroyed after corona aging. The relation of space charge distribution with the concentration of the nano-TiO2 particles and the aging time is explored. Results show that an increase in dielectric permittivity of the nanocomposite films is observed with increasing filler concentration. However, the accumulation of space charge decreases with increasing nano-TiO2 particles concentration for the same corona aging time, and depends on the dielectric permittivity of the nanocomposite films.

A particle accelerator employing transient space charge potentials

DOEpatents

Post, R.F.

1988-02-25

The invention provides an accelerator for ions and charged particles. The plasma is generated and confined in a magnetic mirror field. The electrons of the plasma are heated to high temperatures. A series of local coils are placed along the axis of the magnetic mirror field. As an ion or particle beam is directed along the axis in sequence the coils are rapidly pulsed creating a space charge to accelerate and focus the beam of ions or charged particles. 3 figs.

Influences of the coordinate dependent noncommutative space on charged and spin currents

NASA Astrophysics Data System (ADS)

Ren, Ya-Jie; Ma, Kai

2018-06-01

We study the charged and spin currents on a coordinate dependent noncommutative space. Starting from the noncommutative extended relativistic equation of motion, the nonrelativistic approximation is obtained by using the Foldy-Wouthuysen transformation, and then the charged and spin currents are derived by using the extended Drude model. We find that the charged current is twisted by modifying the off-diagonal elements of the Hall conductivity, however, the spin current is not affected up to leading order of the noncommutative parameter.

EOS-AM1 Nickel Hydrogen Cell

NASA Technical Reports Server (NTRS)

Bennett, Charles W.; Keys, Denney J.; Rao, Gopalakrishna M.; Wannemacher, Hari E.; Vaidyanathan, Harry

1997-01-01

This paper reports the interim results of the Earth Observing System AM-1 project (EOS-AM-1) nickel hydrogen cell life test being conducted under contract to National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) at the Lockheed Martin Missile and Space (LMMS) facility in East Windsor, NJ; and at COMSAT Labs., Clarksburg, MD. The purpose of die tests is to verify that the EOS-AM-1 cell design can meet five years of real-time Low Earth Orbit (LEO) cycling. The tests include both real-time LEO and accelerated stress tests. At LMMS, the first real-time LEO simulated 99 minute orbital cycle started on February 7, 1994 and the test has been running continuously since that time, with 18,202 LEO cycles completed as of September 1, 1997. Each cycle consists of a 64 minute charge (VT at 1.507 volts per cell, 1.06 C/D ratio, followed by 0.6 ampere trickle charge) and a 35 minute constant power discharge at 177 watts (22.5% DOD). At COMSAT, the accelerated stress test consists of 90 minute orbital cycles at 60% DOD with a 30 minute discharge at 60 amperes and a 60 minute charge at 40 amperes (VT at 1.54 volts per cell to 1.09 C/D ratio, followed by 0.6 ampere trickle charge). The real-time LEO life test battery consists of seven, 50AH (nameplate rating) Eagle-Picher, Inc. (EPI) Mantech cells manufactured into three, 3-cell pack assemblies (there are two place holder cells that are not part of the life test electrical circuit). The test pack is configured to simulate the conductive thermal design of the spacecraft battery, including: conductive aluminum sleeves, 3-cell pack aluminum baseplate, and honeycomb panel all mounted to a liquid (-5 C) cold plate. The entire assembly is located in a thermal chamber operating at +30 C. The accelerated stress test unit consists of five cells mounted in machined aluminum test sleeves and is operating at +10 C. The real-time LEO life test battery has met all performance requirements through the first 18,202 cycles, including: end of charge mid discharge cell voltages and voltage gradients; end of charge and discharge cell pressures; within cell and between cell temperature gradients; discharge capacity; current and power levels; and all charge parameters. The accelerated stress test battery has completed 11,998 cycles when the test was terminated. The stress test unit met all test parameters. This paper reports battery perfortnances as a funcfion of cycle life for both the real-time LEO and the accelerated life test regimes.

EOS-AM1 Nickel Hydrogen Cell Interim Life Test Report

NASA Technical Reports Server (NTRS)

Bennett, Charles W.; Keys, D. J.; Rao, G. M.; Wannemacher, H. E.; Vaidyanathan, Hari

1998-01-01

This paper reports the interim results Earth Observing System AM-1 project (EOS-AM-1) nickel hydrogen cell life test being conducted under contract to National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) at the Lockheed Martin Missiles and Space (LMMS) facility in East Windsor, NJ; and at COMSAT Labs., Clarksburg, MD. The purpose of the tests is to verify that the EOS-AM-1 cell design can meet five years of real-time Low Earth Orbit (LEO) cycling. The tests include both real-time LEO and accelerated stress tests. At LMMS, the first real-time LEO simulated 99 minute orbital cycle started on February 7, 1994 and the test has been running continuously since that time, with 18202 LEO cycles completed as of September 1, 1997. Each cycle consists of a 64-minute charge (VT at 1,507 volts per cell, 1.06 C/D ratio, followed by 0.6 ampere trickle charge) and a 35 minute constant power discharge at 177 watts (22.5 percent DOD). At COMSAT, the accelerated stress test consists of 90 minute orbital cycles at 60 percent DOD with a 30 minute discharge at 60 amperes and a 60 minute charge at 40 amperes (VT at 1.54 volts per cell to 1.90 C/D ratio, followed by 0.6 ampere trickle charge). The real-time LEO life test battery consists of seven, 50AH (nameplate rating) Eagle-Picher, Inc. (EPI) Mantech cells manufactured into three, 3-cell pack assemblies (there are two place holder cells that are not part of the life test electrical circuit). The test pack is configured to simulate the conductive thermal design of the spacecraft battery, including: conductive aluminum sleeves, 3-cell pack aluminum baseplate, and honeycomb panel all mounted to a liquid (minus 5 deg) cold plate. The entire assembly is located in a thermal chamber operating at plus 3 deg. The accelerated stress test unit consists of five cells mounted in machined aluminum test sleeves and is operating at plus 10 deg. The real-time LEO life test battery has met all performance requirements through the first 18,202 cycles, including: end of charge and discharge cell voltages and voltage gradients; end of charge and discharge cells pressures; within cell and between cell temperature gradients dischare capacity; current and power levels; and all charge parameters. The accelerated stress test battery has completed 11998 cycles when the test was terminated. The stress test unit met all test parameters. This paper reports battery performances as a function of cycle life for both the real-time LEO and the accelerated life test regimes.

ISS Local Environment Spectrometers (ISLES)

NASA Technical Reports Server (NTRS)

Krause, Linda Habash; Gilchrist, Brian E.

2014-01-01

In order to study the complex interactions between the space environment surrounding the ISS and the ISS surface materials, we propose to use lowcost, high-TRL plasma sensors on the ISS robotic arm to probe the ISS space environment. During many years of ISS operation, we have been able to condut effective (but not perfect) extravehicular activities (both human and robotic) within the perturbed local ISS space environment. Because of the complexity of the interaction between the ISS and the LEO space environment, there remain important questions, such as differential charging at solar panel junctions (the so-called "triple point" between conductor, dielectric, and space plasma), increased chemical contamination due to ISS surface charging and/or thruster activation, water dumps, etc, and "bootstrap" charging of insulating surfaces. Some compelling questions could synergistically draw upon a common sensor suite, which also leverages previous and current MSFC investments. Specific questions address ISS surface charging, plasma contactor plume expansion in a magnetized drifting plasma, and possible localized contamination effects across the ISS.

Exact solutions to model surface and volume charge distributions

NASA Astrophysics Data System (ADS)

Mukhopadhyay, S.; Majumdar, N.; Bhattacharya, P.; Jash, A.; Bhattacharya, D. S.

2016-10-01

Many important problems in several branches of science and technology deal with charges distributed along a line, over a surface and within a volume. Recently, we have made use of new exact analytic solutions of surface charge distributions to develop the nearly exact Boundary Element Method (neBEM) toolkit. This 3D solver has been successful in removing some of the major drawbacks of the otherwise elegant Green's function approach and has been found to be very accurate throughout the computational domain, including near- and far-field regions. Use of truly distributed singularities (in contrast to nodally concentrated ones) on rectangular and right-triangular elements used for discretizing any three-dimensional geometry has essentially removed many of the numerical and physical singularities associated with the conventional BEM. In this work, we will present this toolkit and the development of several numerical models of space charge based on exact closed-form expressions. In one of the models, Particles on Surface (ParSur), the space charge inside a small elemental volume of any arbitrary shape is represented as being smeared on several surfaces representing the volume. From the studies, it can be concluded that the ParSur model is successful in getting the estimates close to those obtained using the first-principles, especially close to and within the cell. In the paper, we will show initial applications of ParSur and other models in problems related to high energy physics.

A Triboelectric Sensor Array for Electrostatic Studies on the Lunar Surface

NASA Technical Reports Server (NTRS)

Johansen, Michael R.; Mackey, Paul J.; Calle, C. I.

2015-01-01

The moons electrostatic environment requires careful consideration in the development of future lunar landers. Electrostatically charged dust was well documented during the Apollo missions to cause thermal control, mechanical, and visibility issues. The fine dust particles that make up the surface are electrostatically charged as a result of numerous charging mechanisms. The relatively dry conditions on the moon creates a prime tribocharging environment during surface operations. The photoelectric effect is dominant for lunar day static charging, while plasma electrons are the main contributor for lunar night electrostatic effects. Electrostatic charging is also dependent on solar intensity, Earth-moon relative positions, and cosmic ray flux. This leads to a very complex and dynamic electrostatic environment that must be studied for the success of long term lunar missions.In order to better understand the electrostatic environment of planetary bodies, Kennedy Space Center, in previous collaboration with the Jet Propulsion Laboratory, has developed an electrostatic sensor suite. One of the instruments included in this package is the triboelectric sensor array. It is comprised of strategically selected materials that span the triboelectric series and that also have previous spaceflight history. In this presentation, we discuss detailed testing with the triboelectric sensor array performed at Kennedy Space Center. We will discuss potential benefits and use cases of this low mass, low cost sensor package, both for science and for mission success.

Bounding Extreme Spacecraft Charging in the Lunar Environment

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Parker, Linda N.

2008-01-01

Robotic and manned spacecraft from the Apollo era demonstrated that the lunar surface in daylight will charge to positive potentials of a few tens of volts because the photoelectron current dominates the charging process. In contrast, potentials of the lunar surface in darkness which were predicted to be on the order of a hundred volts negative in the Apollo era have been shown more recently to reach values of a few hundred volts negative with extremes on the order of a few kilovolts. The recent measurements of night time lunar surface potentials are based on electron beams in the Lunar Prospector Electron Reflectometer data sets interpreted as evidence for secondary electrons generated on the lunar surface accelerated through a plasma sheath from a negatively charged lunar surface. The spacecraft potential was not evaluated in these observations and therefore represents a lower limit to the magnitude of the lunar negative surface potential. This paper will describe a method for obtaining bounds on the magnitude of lunar surface potentials from spacecraft measurements in low lunar orbit based on estimates of the spacecraft potential. We first use Nascap-2k surface charging analyses to evaluate potentials of spacecraft in low lunar orbit and then include the potential drops between the ambient space environment and the spacecraft to the potential drop between the lunar surface and the ambient space environment to estimate the lunar surface potential from the satellite measurements.

Space activities and radiation protection of crew members

NASA Astrophysics Data System (ADS)

Straube, Ulrich; Berger, Thomas; Reitz, Guenther; Facius, Rainer; Reiter, Thomas; Kehl, Marcel; Damann, M. D. Volker; Tognini, Michel

Personnel working as crew in space-based activities e.g. professional astronauts and cosmo-nauts but also -to a certain extend-space flight participants ("space tourists"), demand health and safety considerations that have to include radiation protection measures. The radiation environment that a crew is exposed to during a space flight, differs significantly to that found on earth including commercial aviation, mainly due to the presence of heavy charged particles with great potential for biological damage. The exposure exceeds those routinely received by terrestrial radiation workers. A sequence of activities has to be conducted targeting to mitigate adverse effects of space radiation. Considerable information is available and applied through the joint efforts of the Space Agencies that are involved in the operations of the International Space Station, ISS. This presentation will give an introduction to the current measures for ra-diation monitoring and protection of astronauts of the European Space Agency (ESA). It will include information: on the radiation protection guidelines that shall ensure the proper imple-mentation and execution of radiation protection measures, the operational hardware used for radiation monitoring and personal dosimetry on ISS, as well as information about operational procedures that are applied.

Millimeter-Wave Generation Via Plasma Three-Wave Mixing

DTIC Science & Technology

1988-06-01

are coupled to a third space -charge wave with dispersion 2w W k -k k . (16) A plasma-loaded-waveguide mode is excited at the intersection of this...DISPERSION "FAST" W PLASMA WAVE Wc PLASMA WAVE A-lA oppositely directed EPWs with different phase velocities (wp/k., and wO/k. 2) are coupled to a third ... space -charge wave with dispersion 2w I- k k .(16) e 2 A plaama-loaded-waveguide mode is excited at the intersection of this coupled space-charge wave

Experimental Charging Behavior of Orion UltraFlex Array Designs

NASA Technical Reports Server (NTRS)

Golofaro, Joel T.; Vayner, Boris V.; Hillard, Grover B.

2010-01-01

The present ground based investigations give the first definitive look describing the charging behavior of Orion UltraFlex arrays in both the Low Earth Orbital (LEO) and geosynchronous (GEO) environments. Note the LEO charging environment also applies to the International Space Station (ISS). The GEO charging environment includes the bounding case for all lunar mission environments. The UltraFlex photovoltaic array technology is targeted to become the sole power system for life support and on-orbit power for the manned Orion Crew Exploration Vehicle (CEV). The purpose of the experimental tests is to gain an understanding of the complex charging behavior to answer some of the basic performance and survivability issues to ascertain if a single UltraFlex array design will be able to cope with the projected worst case LEO and GEO charging environments. Stage 1 LEO plasma testing revealed that all four arrays successfully passed arc threshold bias tests down to -240 V. Stage 2 GEO electron gun charging tests revealed that only the front side area of indium tin oxide coated array designs successfully passed the arc frequency tests

Simulation on the dynamic charge behavior of vacuum flashover developing across insulator involving outgassing

NASA Astrophysics Data System (ADS)

Sun, Guang-Yu; Guo, Bao-Hong; Song, Bai-Peng; Su, Guo-Qiang; Mu, Hai-Bao; Zhang, Guan-Jun

2018-06-01

A 2D simulation based on particle-in-cell and Monte Carlo collision algorithm is implemented to investigate the accumulation and dissipation of surface charges on an insulator during flashover with outgassing in vacuum. A layer of positive charges is formed on the insulator after the secondary electrons emission (SEE) reaches saturation. With the build-up of local pressure resulting from gas desorption, the incident energy of electrons is affected by electron-neutral collisions and field distortion, remarkably decreasing the charge density on the insulator. Gas desorption ionization initiates near the anode, culminating, and then abates, followed by a steady and gradual augmentation as the negatively charged surface spreads towards the cathode and halts the SEE nearby. The initiation of flashover development is discussed in detail, and a subdivision of flashover development is proposed, including an anode-initiated desorption ionization avalanche, establishment of a plasma sheath, and plasma expansion. The transform from saturation to explosion of space charges and dissipation of the surface charge are revealed, which can be explained by the competition between multipactor electrons and ionized electrons.

Space charge inhibition effect of nano-Fe{sub 3}O{sub 4} on improvement of impulse breakdown voltage of transformer oil based on improved Kerr optic measurements

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

Yang, Qing, E-mail: yangqing@cqu.edu.cn; Yu, Fei; Sima, Wenxia

Transformer oil-based nanofluids (NFs) with 0.03 g/L Fe{sub 3}O{sub 4} nanoparticle content exhibit 11.2% higher positive impulse breakdown voltage levels than pure transformer oils. To study the effects of the Fe{sub 3}O{sub 4} nanoparticles on the space charge in transformer oil and to explain why the nano-modified transformer oil exhibits improved impulse breakdown voltage characteristics, the traditional Kerr electro-optic field mapping technique is improved by increasing the length of the parallel-plate electrodes and by using a photodetector array as a high light sensitivity device. The space charge distributions of pure transformer oil and of NFs containing Fe{sub 3}O{sub 4} nanoparticlesmore » can be measured using the improved Kerr electro-optic field mapping technique. Test results indicate a significant reduction in space charge density in the transformer oil-based NFs with the Fe{sub 3}O{sub 4} nanoparticles. The fast electrons are captured by the nanoparticles and are converted into slow-charged particles in the NFs, which then reduce the space charge density and result in a more uniform electric field distribution. Streamer propagation in the NFs is also obstructed, and the breakdown strengths of the NFs under impulse voltage conditions are also improved.« less

Magnetically insulated coaxial vacuum diode with partial space-charge-limited explosive emission from edge-type cathode

NASA Astrophysics Data System (ADS)

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.

Magnetically insulated coaxial vacuum diode with partial space-charge-limited explosive emission from edge-type cathode

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

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

Specification of the near-Earth space environment with SHIELDS

DOE PAGES

Jordanova, Vania Koleva; Delzanno, Gian Luca; Henderson, Michael Gerard; ...

2017-11-26

Here, predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure is one example of “space weather” and a big space physics challenge. A project recently funded through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program aims at developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to understand the dynamics of the surface charging environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- andmore » micro-scale. Important physics questions related to particle injection and acceleration associated with magnetospheric storms and substorms, as well as plasma waves, are investigated. These challenging problems are addressed using a team of world-class experts in the fields of space science and computational plasma physics, and state-of-the-art models and computational facilities. A full two-way coupling of physics-based models across multiple scales, including a global MHD (BATS-R-US) embedding a particle-in-cell (iPIC3D) and an inner magnetosphere (RAM-SCB) codes, is achieved. New data assimilation techniques employing in situ satellite data are developed; these provide an order of magnitude improvement in the accuracy in the simulation of the SCE. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code that can be used for reanalysis of satellite failures or for satellite design.« less

Specification of the near-Earth space environment with SHIELDS

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

Jordanova, Vania Koleva; Delzanno, Gian Luca; Henderson, Michael Gerard

Here, predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure is one example of “space weather” and a big space physics challenge. A project recently funded through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program aims at developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to understand the dynamics of the surface charging environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- andmore » micro-scale. Important physics questions related to particle injection and acceleration associated with magnetospheric storms and substorms, as well as plasma waves, are investigated. These challenging problems are addressed using a team of world-class experts in the fields of space science and computational plasma physics, and state-of-the-art models and computational facilities. A full two-way coupling of physics-based models across multiple scales, including a global MHD (BATS-R-US) embedding a particle-in-cell (iPIC3D) and an inner magnetosphere (RAM-SCB) codes, is achieved. New data assimilation techniques employing in situ satellite data are developed; these provide an order of magnitude improvement in the accuracy in the simulation of the SCE. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code that can be used for reanalysis of satellite failures or for satellite design.« less

Electromagnetic Compatibility for the Space Shuttle

NASA Technical Reports Server (NTRS)

Scully, Robert C.

2004-01-01

This slide presentation reviews the Space Shuttle electromagnetic compatibility (EMC). It includes an overview of the design of the shuttle with the areas that are of concern for the electromagnetic compatibility. It includes discussion of classical electromagnetic interference (EMI) and the work performed to control the electromagnetic interference. Another area of interest is electrostatic charging and the threat of electrostatic discharge and the attempts to reduce damage to the Shuttle from these possible hazards. The issue of electrical bonding is als reviewed. Lastly the presentation reviews the work performed to protect the shuttle from lightning, both in flight and on the ground.

Natural orbital environment definition guidelines for use in aerospace vehicle development

NASA Technical Reports Server (NTRS)

Anderson, B. Jeffrey (Editor); Smith, Robert E. (Compiler)

1994-01-01

This document provides definitions of the natural near-Earth space environment suitable for use in the initial development/design phase of any space vehicle. The natural environment includes the neutral atmosphere, plasma, charged particle radiation, electromagnetic radiation (EMR), meteoroids, orbital debris, magnetic field, physical and thermal constants, and gravitational field. Communications and other unmanned satellites operate in geosynchronous-Earth orbit (GEO); therefore, some data are given for GEO, but emphasis is on altitudes from 200 km to 1000 km (low-Earth orbit (LEO)). This document does not cover the induced environment of other effects resulting from presence of the space vehicle. Manmade factors are included as part of the ambient natural environment; i.e., orbital debris and radio frequency (RF) noise generated on Earth, because they are not caused by the presence of the space vehicle but form part of the ambient environment that the space vehicle experiences.

Lanzerotti to Head New AGU Journal on Space Weather

NASA Astrophysics Data System (ADS)

Lifland, Jonathan

Louis J. Lanzerotti has been named editor of a new AGU online publication devoted to the emerging field of near-Earth space conditions and their effects on technical systems. Space Weather: The International Journal of Research and Applications, will be the first journal dedicated solely to the subject, and will include peer-reviewed research, as well as news, features, and opinion articles. A quarterly magazine digest will also be published from the online edition and distributed free of charge to space weather professionals. Lanzerotti, a longtime AGU member who was elected an AGU Fellow in 1985, is currently a consulting physicist at Lucent Technologies Bell Laboratories, and a distinguished research professor at the New Jersey Institute of Technology. He also serves on the governing board of the American Institute of Physics. He is author or co-author of more than 500 publications, including many related to space weather and its effects on communications.

The Exploration Portable Electrostatic Detector (xPED)

NASA Technical Reports Server (NTRS)

Jackson, Telana L.; Farrell, William M.

2012-01-01

Astronauts and rovers, while exploring dynamic environments, can experience charge buildup through Tribo-charging (contact electrification). Charge levels can become substantially high. especially in areas where photoelectric and plasma currents are reduced (e.g. lunar polar crater). Tribo-charging in areas that have little to no charge dissipative path can be severe, leaving an astronaut or roving object to remain charged for extended periods of time. Charge buildup on space suits and/or rovers is expected to present significant hazards to missions, such as electrostatic discharge and arcing, dust adhesion to space suits/equipment, and destruction of equipment. The avoidance of hazards associated with charge buildup is critical for future NASA missions to near earth objects, the Moon and Mars. The Exploration Portable Electrostatic Device (xPED) will allow astronauts to determine their charge state, and also characterize the electrical environment from their excursions. xPED would benefit manned, as well as robotic missions.

Effect of electric charge on the adhesion of human blood platelets.

PubMed

Lowkis, B; Szymonowicz, M

1993-01-01

The paper presents the results of research into the effect of the size and depth of the implanted electric charge on the adhesion of human blood platelets. The experiments were carried out on polyethylene terephthalate PET foil of 36 microns thickness. The electret formation process was carried out in an electron-beam device. The electrization conditions were such that electrets with the excess electric charge accumulated at various depths were obtained. The selection of conditions was verified by investigating the space charge distribution with the use of the virtual electrode method. The microscopic observation of non-electrified foils and electrets as well as the quantitative examination of the adhesion of human blood platelets has explicitly confirmed the positive influence of the electret effect on the thrombogenesis of PET foil. This made it possible to define the optimum electrization conditions. The research has additionally indicated that the relationship between the amount of adherent blood platelets and the size of the electric charge is not a simple relation of the kind: the larger negative charge, the more thrombogenic material. The decisive and positive effect of the space charge has been confirmed by analysing the effectiveness of the surface and space charge.

Dielectrics for long term space exposure and spacecraft charging: A briefing

NASA Technical Reports Server (NTRS)

Frederickson, A. R.

1989-01-01

Charging of dielectrics is a bulk, not a surface property. Radiation driven charge stops within the bulk and is not quickly conducted to the surface. Very large electric fields develop in the bulk due to this stopped charge. At space radiation levels, it typically requires hours or days for the internal electric fields to reach steady state. The resulting electric fields are large enough to produce electrical failure within the insulator. This type failure is thought to produce nearly all electric discharge anomalies. Radiation also induces bond breakage, creates reactive radicals, displaces atoms and, in general, severely changes the chemistry of the solid state material. Electric fields can alter this process by reacting with charged species, driving them through the solid. Irradiated polymers often lose as much as a percent of their mass, or more, at exposures typical in space. Very different aging or contaminant emission can be induced by the stopped charge electric fields. These radiation effects are detailed.

Active space debris charging for contactless electrostatic disposal maneuvers

NASA Astrophysics Data System (ADS)

Schaub, Hanspeter; Sternovsky, Zoltán

2014-01-01

The remote charging of a passive object using an electron beam enables touchless re-orbiting of large space debris from geosynchronous orbit (GEO) using electrostatic forces. The advantage of this method is that it can operate with a separation distance of multiple craft radii, thus reducing the risk of collision. The charging of the tug-debris system to high potentials is achieved by active charge transfer using a directed electron beam. Optimal potential distributions using isolated- and coupled-sphere models are discussed. A simple charging model takes into account the primary electron beam current, ultra-violet radiation induced photoelectron emission, collection of plasma particles, secondary electron emission and the recapture of emitted particles. The results show that through active charging in a GEO space environment high potentials can be both achieved and maintained with about a 75% transfer efficiency. Further, the maximum electrostatic tractor force is shown to be insensitive to beam current levels. This latter later result is important when considering debris with unknown properties.

Effect of Temperature on Formation and Stability of Shallow Trap at a Dielectric Interface of the Multilayer

NASA Astrophysics Data System (ADS)

Rogti, F.

2015-12-01

Space-charge behavior at dielectric interfaces in multilayer low-density polyethylene (LDPE) and fluorinated ethylene propylene (FEP) subjected to a direct-current (DC) field has been investigated as a function of temperature using the pulsed electroacoustic technique. A sandwich structure constituted by two nonidentical LDPE/FEP dielectric films was used to study the charging propensity of electrode/dielectric and dielectric/dielectric interfaces. The time dependence of the space-charge distribution was subsequently recorded at four temperatures, 20°C, 25°C, 40°C, and 60°C, under field (polarization) and short-circuit (depolarization) conditions. The experimental results demonstrate that temperature plays a significant role in the space-charge dynamics at the dielectric interface. It affects the charge injection, increases the charge mobility and electrical conductivity, and increases the density of shallow traps and trap filling. It is found that traps formed during polarization at high temperature do not remain stable after complete discharge of the multidielectric structure and when poled at low temperatures.

Internal Structure of Charged Particles in a GRT Gravitational Model

NASA Astrophysics Data System (ADS)

Khlestkov, Yu. A.; Sukhanova, L. A.

2018-05-01

With the help of an exact solution of the Einstein and Maxwell equations, the internal structure of a multiply connected space of wormhole type with two unclosed static throats leading out of it into two parallel vacuum spaces or into one space is investigated in GRT for a free electric field and dust-like matter. The given geometry is considered as a particle-antiparticle pair with fundamental constants arising in the form of first integrals in the solution of the Cauchy problem - electric charges ±e of opposite sign in the throats and rest mass m0 - the total gravitational mass of the inner world of the particle in the throat. With the help of the energy conservation law, the unremovable rotation of the internal structure is included and the projection of the angular momentum of which onto the rotation axis is identified with the z-projection of the spin of the charged particle. The radius of 2-Gaussian curvature of the throat R* is identified with the charge radius of the particle, and the z-projection of the magnetic moment and the g-factor are found. The feasibility of the given gravitational model is confirmed by the found condition of independence of the spin quantum number of the electron and the proton s = 1/2 of the charge radius R* and the relativistic rest mass m* of the rotating throat, which is reliably confirmed experimentally, and also by the coincidence with high accuracy of the proton radius calculated in the model R*p = 0.8412·10-13 cm with the value of the proton charge radius obtained experimentally by measuring the Lamb shift on muonic hydrogen. The electron in the given model also turns out to be a structured particle with radius R*e = 3.8617·10-11 cm.

Application of Dusty Plasmas for Space

NASA Astrophysics Data System (ADS)

Bhavasar, Hemang; Ahuja, Smariti

In space, dust particles alone are affected by gravity and radiation pressure when near stars and planets. When the dust particles are immersed in plasma, the dust is usually charged either by photo ionization, due to incident UV radiation, secondary electron emission, due to collisions with energetic ions and electrons, or absorption of charged particles, due to collisions with thermal ions and electrons. A 1 micron radius dust particle in a plasma with an electron temperature of a few eV, will have a charge corresponding to a few thousand electron volts, with a resulting charge to mass ratio, Q/m ¡1. They will also be affected by electric and magnetic fields. Since the electrons are magnetized in these regions, electron E B or diamagnetic cross-field drifts may drive instabilities. Dust grains (micron to sub-micron sized solid particles) in plasma and/or radiative environments can be electrically charged by processes such as plasma current collection or photoemission. The effect of charged dust on known electrojet instabil-ities and low frequency dust acoustic and dust drift instabilities. As the plasma affects the dust particles, the dust particles can affect the plasma environment. In Dust Plasma, Plasma is Combination of ions and electrons. Dusty plasmas (also known as complex plasmas) are ordinary plasmas with embedded solid particles consisting of electrons, ions, and neutrals. The particles can be made of either dielectric or conducting materials, and can have any shape. The typical size range is anywhere from 100 nm up to say 100 m. Most often, these small objects or dust particles are electrically charged. Dusty plasmas are ubiquitous in the universe as proto-planetary and solar nebulae, molecular clouds, supernova explosions, interplanetary medium, circumsolar rings, and steroids. Closer to earth, there are the noctilucent clouds, clouds of tiny (charged) ice particles that form in the summer polar mesosphere at an altitude of about 85 km. In processing plasmas, dust particles are actually grown in the discharge from the reactive gases used to form the plasmas. Perhaps the most intriguing aspect of dusty plasmas is that the particles can be directly imaged and their dynamic behavior recorded as digital images. This is accomplished by laser light scattering from the particles. Since the particle mass is relatively high, their dynamical timescales are much longer than that of the ions or electrons. Dusty plasmas has a broad range of applications including interplanetary space dust, comets, planetary rings, dusty surfaces in space, and aerosols in the atmosphere.

14 CFR 221.52 - Airport to airport application, accessorial services.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Airport to airport application, accessorial... Charges § 221.52 Airport to airport application, accessorial services. Tariffs shall specify whether or not the fares therein include services in addition to airport-to-airport transportation. ...

14 CFR 221.52 - Airport to airport application, accessorial services.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Airport to airport application, accessorial... Charges § 221.52 Airport to airport application, accessorial services. Tariffs shall specify whether or not the fares therein include services in addition to airport-to-airport transportation. ...

14 CFR 221.52 - Airport to airport application, accessorial services.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Airport to airport application, accessorial... Charges § 221.52 Airport to airport application, accessorial services. Tariffs shall specify whether or not the fares therein include services in addition to airport-to-airport transportation. ...

14 CFR 221.52 - Airport to airport application, accessorial services.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Airport to airport application, accessorial... Charges § 221.52 Airport to airport application, accessorial services. Tariffs shall specify whether or not the fares therein include services in addition to airport-to-airport transportation. ...

14 CFR 221.52 - Airport to airport application, accessorial services.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Airport to airport application, accessorial... Charges § 221.52 Airport to airport application, accessorial services. Tariffs shall specify whether or not the fares therein include services in addition to airport-to-airport transportation. ...

The Effects of Space-Charge on the Dynamics of the Ion Booster in the Jefferson Lab EIC (JLEIC)

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

Bogacz, Alex; Nissen, Edward

Optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime is proposed. This study is motivated by the ultra-high luminosity promised by the JLEIC accelerator complex, which poses several beam dynamics and lattice design challenges for its individual components. We examine the effects of space charge on the dynamics of the booster synchrotron for the proposed JLEIC electron ion collider. This booster will inject and accumulate protons and heavy ions at an energy of 280 MeV and then engage in a process of acceleration and electron cooling to bring it to its extraction energy of 8more » GeV. This would then be sent into the ion collider ring part of JLEIC. In order to examine the effects of space charge on the dynamics of this process we use the software SYNERGIA.« less

Smart sensors II; Proceedings of the Seminar, San Diego, CA, July 31, August 1, 1980

NASA Astrophysics Data System (ADS)

Barbe, D. F.

1980-01-01

Topics discussed include technology for smart sensors, smart sensors for tracking and surveillance, and techniques and algorithms for smart sensors. Papers are presented on the application of very large scale integrated circuits to smart sensors, imaging charge-coupled devices for deep-space surveillance, ultra-precise star tracking using charge coupled devices, and automatic target identification of blurred images with super-resolution features. Attention is also given to smart sensors for terminal homing, algorithms for estimating image position, and the computational efficiency of multiple image registration algorithms.

Acoustic charge transport technology investigation for advanced development transponder

NASA Technical Reports Server (NTRS)

Kayalar, S.

1993-01-01

Acoustic charge transport (ACT) technology has provided a basis for a new family of analog signal processors, including a programmable transversal filter (PTF). Through monolithic integration of ACT delay lines with GaAs metal semiconductor field effect transistor (MESFET) digital memory and controllers, these devices significantly extend the performance of PTF's. This article introduces the basic operation of these devices and summarizes their present and future specifications. The production and testing of these devices indicate that this new technology is a promising one for future space applications.

Charged black lens in de Sitter space

NASA Astrophysics Data System (ADS)

Tomizawa, Shinya

2018-02-01

We obtain a charged black lens solution in the five-dimensional Einstein-Maxwell-Chern-Simons theory with a positive cosmological constant. It is shown that the solution obtained here describes the formation of a black hole with the spatial cross section of a sphere from that of the lens space of L (n ,1 ) in five-dimensional de Sitter space.

The Development Of New Space Charge Compensation Methods For Multi-Components Ion Beam Extracted From ECR Ion Source at IMP

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

Ma, L.; Zhao, H.W.; Cao, Y.

2005-03-15

Two new space charge compensation methods developed in IMP are discussed in this paper. There are negative high voltage electrode method (NHVEM) and electronegative charge gas method (EGM). Some valuable experimental data have been achieved, especially using electronegative gas method in O6+ and O7+ dramatic and stable increasing of ion current was observed.

Computer and laboratory simulation of interactions between spacecraft surfaces and charged-particle environments

NASA Technical Reports Server (NTRS)

Stevens, N. J.

1979-01-01

Cases where the charged-particle environment acts on the spacecraft (e.g., spacecraft charging phenomena) and cases where a system on the spacecraft causes the interaction (e.g., high voltage space power systems) are considered. Both categories were studied in ground simulation facilities to understand the processes involved and to measure the pertinent parameters. Computer simulations are based on the NASA Charging Analyzer Program (NASCAP) code. Analytical models are developed in this code and verified against the experimental data. Extrapolation from the small test samples to space conditions are made with this code. Typical results from laboratory and computer simulations are presented for both types of interactions. Extrapolations from these simulations to performance in space environments are discussed.

Negative space charge effects in photon-enhanced thermionic emission solar converters

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

Segev, G.; Weisman, D.; Rosenwaks, Y.

2015-07-06

In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionicmore » converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163.« less

Survey of International Space Station Charging Events

NASA Technical Reports Server (NTRS)

Craven, P. D.; Wright, Kenneth H., Jr.; Minow, Joseph I.; Coffey, Victoria N.; Schneider, Todd A.; Vaughn, Jason A.; Ferguson, Dale C.; Parker, Linda N.

2009-01-01

With the negative grounding of the 160V Photovoltaic (PV) arrays, the International Space Station (ISS) can experience varied and interesting charging events. Since August 2006, there has been a multi-probe p ackage, called the Floating Potential Measurement Unit (FPMU), availa ble to provide redundant measurements of the floating potential of th e ISS as well as the density and temperature of the local plasma environment. The FPMU has been operated during intermittent data campaigns since August 2006 and has collected over 160 days of information reg arding the charging of the ISS as it has progressed in configuration from one to three PV arrays and with various additional modules such as the European Space Agency?s Columbus laboratory and the Japan Aeros pace Exploration Agency's Kibo laboratory. This paper summarizes the charging of the ISS and the local environmental conditions that contr ibute to those charging events, both as measured by the FPMU.

Indirect Charged Particle Detection: Concepts and a Classroom Demonstration

NASA Astrophysics Data System (ADS)

Childs, Nicholas B.; Horányi, Mihály; Collette, Andrew

2013-11-01

We describe the principles of macroscopic charged particle detection in the laboratory and their connections to concepts taught in the physics classroom. Electrostatic dust accelerator systems, capable of launching charged dust grains at hypervelocities (1-100 km/s), are a critical tool for space exploration. Dust grains in space typically have large speeds relative to the probes or satellites that encounter them. Development and testing of instruments that look for dust in space therefore depends critically on the availability of fast, well-characterized dust grains in the laboratory. One challenge for the experimentalist is to precisely measure the speed and mass of laboratory dust particles without disturbing them. Detection systems currently in use exploit the well-known effect of image charge to register the passage of dust grains without changing their speed or mass. We describe the principles of image charge detection and provide a simple classroom demonstration of the technique using soup cans and pith balls.

Asymmetric Wormholes via Electrically Charged Lightlike Branes

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

Guendelman, E.; Kaganovich, A.; Nissimov, E.

2010-06-17

We consider a self-consistent Einstein-Maxwell-Kalb-Ramond system in the bulk D = 4 space-time interacting with a variable-tension electrically charged lightlike brane. The latter serves both as a material and charge source for gravity and electromagnetism, as well as it dynamically generates a bulk space varying cosmological constant. We find an asymmetric wormhole solution describing two 'universes' with different spherically symmetric black-hole-type geometries connected through a 'throat' occupied by the lightlike brane. The electrically neutral 'left universe' comprises the exterior region of Schwarzschild-de-Sitter (or pure Schwarzschild) space-time above the inner(Schwarzschild-type) horizon, whereas the electrically charged 'right universe' consists of the exteriormore » Reissner-Nordstroem (or Reissner-Nordstroem-de-Sitter) black hole region beyond the outer Reissner-Nordstroem horizon. All physical parameters of the wormhole are uniquely determined by two free parameters - the electric charge and Kalb-Ramond coupling of the lightlike brane.« less

Novel molecular device based on electrostatic interactions in organic polymers.

PubMed

Kwok, H L; Xu, J B

2004-04-01

A number of researchers have reported attempts to design molecular level devices. One approach is to make use of electrostatic interactions in different parts of a polymeric molecule. This paper reports a means to achieve this by adding space charge to a molecule consisting of symmetric and asymmetric subgroups. Physically, space charge residing in a subgroup produces a dipolar charge layer thereby creating a potential trough in the polymer backbone. By lifting or lowering this potential minimum, it is possible to modify the terminal current. The effect of space charge on the potential profile in the polymer backbone was examined and the change correlated to data on carrier mobilities for OC1C10-PPV reported in the literature. Modulation of space charge in the subgroup allows the manipulation of current flow along the polymer backbone, forming the basis for the development of a molecular device. A first-order analysis suggested that such a device could have current-voltage (I-V) characteristics similar to those of a MOSFET at subthreshold, with an estimated transconductance approximately 1-2 pAV and a cutoff frequency approximately 10(15) Hz.

Distinctive electrical properties in sandwich-structured Al2O3/low density polyethylene nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Si-Jiao; Zha, Jun-Wei; Li, Wei-Kang; Dang, Zhi-Min

2016-02-01

The sandwich-structured Al2O3/low density polyethylene (Al2O3/LDPE) nanocomposite dielectrics consisting of layer-by-layer with different concentration Al2O3 loading were prepared by melt-blending and following hot pressing method. The space charge distribution from pulsed electro-acoustic method and breakdown strength of the nanocomposites were investigated. Compared with the single-layer Al2O3/LDPE nanocomposites, the sandwich-structured nanocomposites remarkably suppressed the space charge accumulation and presented higher breakdown strength. The charges in the sandwich-structured nanocomposites decayed much faster than that in the single-layer nanocomposites, which was attributed to an effective electric field caused by the formation of the interfacial space charges. The energy depth of shallow and deep traps was estimated as 0.73 eV and 1.17 eV in the sandwich-structured nanocomposites, respectively, according to the thermal excitation theoretical model we proposed. This work provides an attractive strategy of design and fabrication of polymer nanocomposites with excellent space charge suppression.

Mechanism of Runaway Electron Generation at Gas Pressures from a Few Atmospheres to Several Tens of Atmospheres

NASA Astrophysics Data System (ADS)

Zubarev, N. M.; Ivanov, S. N.

2018-04-01

The mechanism of runaway electron generation at gas pressures from a few atmospheres to several tens of atmospheres is proposed. According to this mechanism, the electrons pass into the runaway mode in the enhanced field zone that arises between a cathode micropoint—a source of field-emission electrons—and the region of the positive ion space charge accumulated near the cathode in the tails of the developing electron avalanches. As a result, volume gas ionization by runaway electrons begins with a time delay required for the formation of the enhanced field zone. This process determines the delay time of breakdown. The influence of the gas pressure on the formation dynamics of the space charge region is analyzed. At gas pressures of a few atmospheres, the space charge arises due to the avalanche multiplication of the very first field-emission electron, whereas at pressures of several tens of atmospheres, the space charge forms as a result of superposition of many electron avalanches with a relatively small number of charge carriers in each.

Assessment and control of electrostatic charges. [hazards to space missions

NASA Technical Reports Server (NTRS)

Barrett, M.

1974-01-01

The experience is described of NASA and DOD with electrostatic problems, generation mechanisms, and type of electrostatic hazards. Guidelines for judging possible effects of electrostatic charges on space missions are presented along with mathematical formulas and definitions.

Heliospheric Physics and NASA's Vision for Space Exploration

NASA Technical Reports Server (NTRS)

Minow, Joseph I.

2007-01-01

The Vision for Space Exploration outlines NASA's development of a new generation of human-rated launch vehicles to replace the Space Shuttle and an architecture for exploring the Moon and Mars. The system--developed by the Constellation Program--includes a near term (approx. 2014) capability to provide crew and cargo service to the International Space Station after the Shuttle is retired in 2010 and a human return to the Moon no later than 2020. Constellation vehicles and systems will necessarily be required to operate efficiently, safely, and reliably in the space plasma and radiation environments of low Earth orbit, the Earth's magnetosphere, interplanetary space, and on the lunar surface. This presentation will provide an overview of the characteristics of space radiation and plasma environments relevant to lunar programs including the trans-lunar injection and trans-Earth injection trajectories through the Earth's radiation belts, solar wind surface dose and plasma wake charging environments in near lunar space, energetic solar particle events, and galactic cosmic rays and discusses the design and operational environments being developed for lunar program requirements to assure that systems operate successfully in the space environment.

SEPAC data analysis in support of the environmental interaction program

NASA Technical Reports Server (NTRS)

Lin, Chin S.

1990-01-01

Injections of nonrelativistic electron beams from an isolated equipotential conductor into a uniform background of plasma and neutral gas were simulated using a two dimensional electrostatic particle code. The ionization effects of spacecraft charging are examined by including interactions of electrons with neutral gas. The simulations show that the conductor charging potential decreases with increasing neutral background density due to the production of secondary electrons near the conductor surface. In the spacecraft wake, the background electrons accelerated towards the charged space craft produced an enhancement of secondary electrons and ions. Simulations run for longer times indicate that the spacecraft potential is further reduced and short wavelength beam-plasma oscillations appear. The results are applied to explain the space craft charging potential measured during the SEPAC experiments from Spacelab 1. A second paper is presented in which a two dimensional electrostatic particle code was used to study the beam radial expansion of a nonrelativistic electron beam injected from an isolated equipotential conductor into a background plasma. The simulations indicate that the beam radius is generally proportional to the beam electron gyroradius when the conductor is charged to a large potential. The simulations also suggest that the charge buildup at the beam stagnation point causes the beam radial expansion. From a survey of the simulation results, it is found that the ratio of the beam radius to the beam electron gyroradius increases with the square root of beam density and decreases inversely with beam injection velocity. This dependence is explained in terms of the ratio of the beam electron Debye length to the ambient electron Debye length. These results are most applicable to the SEPAC electron beam injection experiments from Spacelab 1, where high charging potential was observed.

Spacecraft Charging Hazards In Low-earth Orbit

NASA Astrophysics Data System (ADS)

Anderson, P. C.

The space environment in low-Earth orbit (LEO) has until recently been considered quite benign to high levels of spacecraft charging. However, it has been found that the DMSP spacecraft at 840 km can charge to very large negative voltages (up to - 2000 V) when encountering intense precipitating electron events (auroral arcs) while traversing the auroral zone. The occurrence frequency of charging events, defined as when the spacecraft charged to levels exceeding 100 V negative, was highly correlated with the 11-year solar cycle with the largest number of events occurring during solar minimum. This was due to the requirement that the background thermal plasma den- sity be low, at most 104 cm-2. During solar maximum, the plasma density is typically well above that level due to the solar EUV ionizing radiation, and although the oc- currence frequency of auroral arcs is considerably greater than at solar minimum, the occurrence of high-level charging is minimal. Indeed, of the over 1200 events found during the most recent solar cycle, none occurred during the last solar maximum. This has implications to a number of LEO satellite programs, including the International Space Station (ISS). The plasma density in the ISS orbit, at a much lower altitude than DMSP, is well above that at 840 km and rarely below 104 cm-2. However, in the wake of the ISS, the plasma density can be 2 orders of magnitude or more lower than the background density and thus conditions are ripe for significant charging effects. With an inclination of 51.6 degrees, the ISS does enter the auroral zone, particularly during geomagnetic storms and substorms when the auroral boundary can penetrate to very low latitudes. This has significant implications for EVA operations in the ISS wake.

Space-charge-sustained microbunch structure in the Los Alamos Proton Storage Ring

NASA Astrophysics Data System (ADS)

Cousineau, S.; Danilov, V.; Holmes, J.; Macek, R.

2004-09-01

We present experimental data from the Los Alamos Proton Storage Ring (PSR) showing long-lived linac microbunch structure during beam storage with no rf bunching. Analysis of the experimental data and particle-in-cell simulations of the experiments indicate that space charge, coupled with energy spread effects, is responsible for the sustained microbunch structure. The simulated longitudinal phase space of the beam reveals a well-defined separatrix in the phase space between linac microbunches, with particles executing unbounded motion outside of the separatrix. We show that the longitudinal phase space of the beam was near steady state during the PSR experiments, such that the separatrix persisted for long periods of time. Our simulations indicate that the steady state is very sensitive to the experimental conditions. Finally, we solve the steady-state problem in an analytic, self-consistent fashion for a set of periodic longitudinal space-charge potentials.

Fatigue in artificially layered Pb(Zr,Ti)O3 ferroelectric films

NASA Astrophysics Data System (ADS)

Jiang, A. Q.; Scott, J. F.; Dawber, M.; Wang, C.

2002-12-01

We have performed fatigue tests on lead zirconate titanate (PZT) multilayers having stacks of Pb(Zr0.8Ti0.2)O3/Pb(Zr0.2Ti0.8)O3 with repeated distances of 12 formula groups. The results are compared with single-layer n-type (0.5 at. % Ta-doped) PZT films. We conclude that fatigue is dominated by space-charge layers in each case, but that in the multilayer such space charge accumulates at the layer interfaces, rather than at the electrode-dielectric interface. The model, which includes both drift and diffusion, is quantitative and yields a rate-limiting mobility of 6.9±0.9×10-12 cm2/V s, in excellent agreement with the oxygen vacancy mobility for perovskite oxides obtained from Zafar et al.

Ion exchange polymers for anion separations

DOEpatents

Jarvinen, Gordon D.; Marsh, S. Fredric; Bartsch, Richard A.

1997-01-01

Anion exchange resins including at least two positively charged sites and a ell-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

29 CFR 4901.31 - Charges for services.

Code of Federal Regulations, 2014 CFR

2014-07-01

... operating duplicating machinery. Not included in direct costs are overhead expenses such as costs of space... this part, in a form that is reasonably usable by the requester. Copies can take the form of paper copy... scholarly research. (ii) Noncommercial scientific institution means an institution that is not operated on a...

29 CFR 4901.31 - Charges for services.

Code of Federal Regulations, 2013 CFR

2013-07-01

... operating duplicating machinery. Not included in direct costs are overhead expenses such as costs of space... this part, in a form that is reasonably usable by the requester. Copies can take the form of paper copy... scholarly research. (ii) Noncommercial scientific institution means an institution that is not operated on a...

29 CFR 4901.31 - Charges for services.

Code of Federal Regulations, 2012 CFR

2012-07-01

... operating duplicating machinery. Not included in direct costs are overhead expenses such as costs of space... this part, in a form that is reasonably usable by the requester. Copies can take the form of paper copy... scholarly research. (ii) Noncommercial scientific institution means an institution that is not operated on a...

41 CFR 102-85.115 - How is the Rent determined?

Code of Federal Regulations, 2010 CFR

2010-07-01

... owned space provided by GSA is based on market appraisals of fully serviced rental values for the..., and security charges are calculated separately and added to the appraised shell Rent to establish the... addition to the shell Rent, the Rent includes amortization of TI allowances used, real estate taxes...

41 CFR 102-85.115 - How is the Rent determined?

Code of Federal Regulations, 2013 CFR

2013-07-01

... owned space provided by GSA is based on market appraisals of fully serviced rental values for the..., and security charges are calculated separately and added to the appraised shell Rent to establish the... addition to the shell Rent, the Rent includes amortization of TI allowances used, real estate taxes...

41 CFR 102-85.115 - How is the Rent determined?

Code of Federal Regulations, 2014 CFR

2014-01-01

... owned space provided by GSA is based on market appraisals of fully serviced rental values for the..., and security charges are calculated separately and added to the appraised shell Rent to establish the... addition to the shell Rent, the Rent includes amortization of TI allowances used, real estate taxes...

14 CFR 158.29 - The Administrator's decision.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.29 The Administrator's... process, including any request by the public agency not to require a class of carriers to collect PFC's... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false The Administrator's decision. 158.29...

14 CFR 158.29 - The Administrator's decision.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.29 The Administrator's... process, including any request by the public agency not to require a class of carriers to collect PFC's... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false The Administrator's decision. 158.29...

14 CFR 158.29 - The Administrator's decision.

Code of Federal Regulations, 2012 CFR

2012-01-01

... (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.29 The Administrator's... process, including any request by the public agency not to require a class of carriers to collect PFC's... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false The Administrator's decision. 158.29...

14 CFR 158.29 - The Administrator's decision.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.29 The Administrator's... process, including any request by the public agency not to require a class of carriers to collect PFC's... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false The Administrator's decision. 158.29...

Ion exchange polymers for anion separations

DOEpatents

Jarvinen, G.D.; Marsh, S.F.; Bartsch, R.A.

1997-09-23

Anion exchange resins including at least two positively charged sites and a well-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

Analyzing Power Supply and Demand on the ISS

NASA Technical Reports Server (NTRS)

Thomas, Justin; Pham, Tho; Halyard, Raymond; Conwell, Steve

2006-01-01

Station Power and Energy Evaluation Determiner (SPEED) is a Java application program for analyzing the supply and demand aspects of the electrical power system of the International Space Station (ISS). SPEED can be executed on any computer that supports version 1.4 or a subsequent version of the Java Runtime Environment. SPEED includes an analysis module, denoted the Simplified Battery Solar Array Model, which is a simplified engineering model of the ISS primary power system. This simplified model makes it possible to perform analyses quickly. SPEED also includes a user-friendly graphical-interface module, an input file system, a parameter-configuration module, an analysis-configuration-management subsystem, and an output subsystem. SPEED responds to input information on trajectory, shadowing, attitude, and pointing in either a state-of-charge mode or a power-availability mode. In the state-of-charge mode, SPEED calculates battery state-of-charge profiles, given a time-varying power-load profile. In the power-availability mode, SPEED determines the time-varying total available solar array and/or battery power output, given a minimum allowable battery state of charge.

Lepton-number-charged scalars and neutrino beamstrahlung

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

Berryman, Jeffrey M.; de Gouvea, Andre; Kelly, Kevin J.

Experimentally, baryon number minus lepton number, $B-L$, appears to be a good global symmetry of nature. We explore the consequences of the existence of gauge-singlet scalar fields charged under $B-L$ $-$dubbed lepton-number-charged scalars, LeNCS $-$and postulate that these couple to the standard model degrees of freedom in such a way that $B-L$ is conserved even at the non-renormalizable level. In this framework, neutrinos are Dirac fermions. Including only the lowest mass-dimension effective operators, some of the LeNCS couple predominantly to neutrinos and may be produced in terrestrial neutrino experiments. We examine several existing constraints from particle physics, astrophysics, and cosmologymore » to the existence of a LeNCS carrying $B-L$ charge equal to two, and discuss the emission of LeNCS's via "neutrino beamstrahlung," which occurs every once in a while when neutrinos scatter off of ordinary matter. In conclusion, we identify regions of the parameter space where existing and future neutrino experiments, including the Deep Underground Neutrino Experiment, are at the frontier of searches for such new phenomena.« less

Lepton-number-charged scalars and neutrino beamstrahlung

DOE PAGES

Berryman, Jeffrey M.; de Gouvea, Andre; Kelly, Kevin J.; ...

2018-04-23

Experimentally, baryon number minus lepton number, $B-L$, appears to be a good global symmetry of nature. We explore the consequences of the existence of gauge-singlet scalar fields charged under $B-L$ $-$dubbed lepton-number-charged scalars, LeNCS $-$and postulate that these couple to the standard model degrees of freedom in such a way that $B-L$ is conserved even at the non-renormalizable level. In this framework, neutrinos are Dirac fermions. Including only the lowest mass-dimension effective operators, some of the LeNCS couple predominantly to neutrinos and may be produced in terrestrial neutrino experiments. We examine several existing constraints from particle physics, astrophysics, and cosmologymore » to the existence of a LeNCS carrying $B-L$ charge equal to two, and discuss the emission of LeNCS's via "neutrino beamstrahlung," which occurs every once in a while when neutrinos scatter off of ordinary matter. In conclusion, we identify regions of the parameter space where existing and future neutrino experiments, including the Deep Underground Neutrino Experiment, are at the frontier of searches for such new phenomena.« less

Lepton-number-charged scalars and neutrino beamstrahlung

NASA Astrophysics Data System (ADS)

Berryman, Jeffrey M.; de Gouvêa, André; Kelly, Kevin J.; Zhang, Yue

2018-04-01

Experimentally, baryon number minus lepton number, B -L , appears to be a good global symmetry of nature. We explore the consequences of the existence of gauge-singlet scalar fields charged under B -L -dubbed lepton-number-charged scalars (LeNCSs)—and postulate that these couple to the standard model degrees of freedom in such a way that B -L is conserved even at the nonrenormalizable level. In this framework, neutrinos are Dirac fermions. Including only the lowest mass-dimension effective operators, some of the LeNCSs couple predominantly to neutrinos and may be produced in terrestrial neutrino experiments. We examine several existing constraints from particle physics, astrophysics, and cosmology to the existence of a LeNCS carrying B -L charge equal to two, and discuss the emission of LeNCSs via "neutrino beamstrahlung," which occurs every once in a while when neutrinos scatter off of ordinary matter. We identify regions of the parameter space where existing and future neutrino experiments, including the Deep Underground Neutrino Experiment, are at the frontier of searches for such new phenomena.

Self-consistent Simulation of Microparticle and Ion Wakefield Configuration

NASA Astrophysics Data System (ADS)

Sanford, Dustin; Brooks, Beau; Ellis, Naoki; Matthews, Lorin; Hyde, Truell

2017-10-01

In a complex plasma, positively charged ions often have a directed flow with respect to the negatively charged dust grains. The resulting interaction between the dust and the flowing plasma creates an ion wakefield downstream from the dust particles, with the resulting positive space region modifying the interaction between the grains and contributing to the observed dynamics and equilibrium structure of the system. Here we present a proof of concept method that uses a molecular dynamics simulation to model the ion wakefield allowing the dynamics of the dust particles to be determined self-consistently. The trajectory of each ion is calculated including the forces from all other ions, which are treated as ``Yukawa particles'' and shielded from thermal electrons and the forces of the charged dust particles. Both the dust grain charge and the wakefield structure are also self-consistently determined for various particle configurations. The resultant wakefield potentials are then used to provide dynamic simulations of dust particle pairs. These results will be employed to analyze the formation and dynamics of field-aligned chains in CASPER's PK4 experiment onboard the International Space Station, allowing examination of extended dust chains without the masking force of gravity. This work was supported by the National Science Foundation under Grants PHY-1414523 and PHY-1740203.

A Perspective of the Science and Mission Challenges in Aeronomy

NASA Technical Reports Server (NTRS)

Spann, James F.

2010-01-01

There are significant fundamental problems for which aeronomy can provide solutions and a critical role in applied science and space weather that only aeronomy can address. Examples of unresolved problems include the interaction of neutral and charged, the role of mass and energy transfer across Earth's interface with space, and the predictability of ionospheric density and composition variability. These and other problems impact the productivity of space assets and thus have a tangible applied dimension. This talk will explore open science problems and barriers to potential mission solutions in an era of constrained resources.

Handbook of geophysics and the space environment, 4th edition

NASA Astrophysics Data System (ADS)

Jursa, A. S.

1985-12-01

This fourth edition of the Air Force Handbook of Geophysics and the Space Environment has been completely revised. It begins with chapters on the sun and its emissions, then treats the Earth's magnetic field and the radiation belts, and follows with chapters on the ionosphere and the aurora. The subject of electrical charging of space vehicles has been of special concern to the Air Force and has been included to aid the designers interested in that problem. The next group of chapters deals with properties of the atmosphere, and the handbook concludes with chapters on the earth sciences and infrared astronomy.

Space physics educational outreach

NASA Technical Reports Server (NTRS)

Copeland, Richard A.

1995-01-01

The goal of this Space Physics Educational Outreach project was to develop a laboratory experiment and classroom lecture on Earth's aurora for use in lower division college physics courses, with the particular aim of implementing the experiment and lecture at Saint Mary's College of California. The strategy is to teach physics in the context of an interesting natural phenomenon by investigating the physical principles that are important in Earth's aurora, including motion of charged particles in electric and magnetic fields, particle collisions and chemical reactions, and atomic and molecular spectroscopy. As a by-product, the undergraduate students would develop an appreciation for naturally occurring space physics phenomena.

Jumbo Space Environment Simulation and Spacecraft Charging Chamber Characterization

DTIC Science & Technology

2015-04-09

PAGE Using Government drawings, specifications, or other data included in this document for any purpose other than Government procurement does not...in any way obligate the U.S. Government. The fact that the Government formulated or supplied the drawings, specifications, or other data does not...including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing

High responsivity secondary ion energy analyzer

NASA Astrophysics Data System (ADS)

Belov, A. S.; Chermoshentsev, D. A.; Gavrilov, S. A.; Frolov, O. T.; Netchaeva, L. P.; Nikulin, E. S.; Zubets, V. N.

2018-05-01

The degree of space charge compensation of a 70 mA, 400 keV pulsed hydrogen ion beam has been measured with the use of an electrostatic energy analyzer of secondary ions. The large azimuthal angle of the analyzer enables a high responsivity, defined as the ratio of the slow secondary ion current emerging from the partially-compensated ion beam to the fast ion beam current. We measured 84% space charge compensation of the ion beam. The current from the slow ions and the rise time from the degree of space charge compensation were measured and compared with expected values.

Space-charge effects in Penning ion traps

NASA Astrophysics Data System (ADS)

Porobić, T.; Beck, M.; Breitenfeldt, M.; Couratin, C.; Finlay, P.; Knecht, A.; Fabian, X.; Friedag, P.; Fléchard, X.; Liénard, E.; Ban, G.; Zákoucký, D.; Soti, G.; Van Gorp, S.; Weinheimer, Ch.; Wursten, E.; Severijns, N.

2015-06-01

The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with K39+ using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.

Transverse Mode Coupling Instability of the Bunch with Oscillating Wake Field and Space Charge

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

Balbekov, V.

Transverse mode coupling instability of a single bunch caused by oscillating wake field is considered in the paper. The instability threshold is found at different frequencies of the wake with space charge tune shift taken into account. The wake phase advance in the bunch length from 0 up tomore » $$4\\pi$$ is investigated. It is shown that the space charge can push the instability threshold up or down dependent on the phase advance. Transition region is investigated thoroughly, and simple asymptotic formulas for the threshold are represented.« less

Study of space charge layer in silver bromide microcrystals by means of ultraviolet photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Tani, Tadaaki; Inami, Yoshiyasu

2000-09-01

Ultraviolet photoelectron spectroscopy has been successfully used to measure the heights of the tops of the valence bands of the surfaces of AgBr layers on Ag substrates for the verification of the space charge layer model. According to this model, the positive space charge layer (composed of negative charges with excess negative kink sites on the surface and corresponding positive charges with interstitial silver ions in the interior) is formed in silver halides, causing the difference in the electronic energy levels between their surface and interior. The depression of the positive space charge layer of AgBr caused by such adsorbates as photographic stabilizers and antifoggants was estimated from the decrease in the ionic conductivity of cubic AgBr microcrystals by the adsorbates. It was confirmed by the decrease in the heights of the tops of the valence bands of the surfaces of AgBr layers caused by the adsorbates in the presence of thin gelatin membranes on their surfaces. This result provided the explanation for the fact that the adsorbates increased the number of the microcrystals which formed latent image centers on the surface and decreased the number of the microcrystals, which formed latent image centers in the interior.

Determination of thermal properties of commercial Ni-MH cells

NASA Astrophysics Data System (ADS)

Darcy, Eric C.

1994-02-01

The test objectives were to evaluate the electrical and thermal performance of commercial Ni-MH cells, evaluate the effectiveness of commercial charge control circuits, assess the abuse tolerance of these cells, and correlate performance and abuse tolerances to cell design via disassembly. Design objectives were to determine which cell designs are most suitable for scale-up and to guide the design of future shuttle and space station based battery chargers. Results, displayed in viewgraph format, include: reflex charging with ICS circuit resulted in premature charge termination; Ni-MH cells appear very tolerant to overcharge at low rates; Enstore's charger is more electrically and thermally efficient at high rates; and Ni-MH cycles much more efficiently than Ni-Cd with the delta-V/delta-t termination.

Wakes and precursor soliton excitations by a moving charged object in a plasma

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

Kumar Tiwari, Sanat, E-mail: sanat-tiwari@uiowa.edu; Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242; Sen, Abhijit, E-mail: senabhijit@gmail.com

2016-02-15

We study the evolution of nonlinear ion acoustic wave excitations due to a moving charged source in a plasma. Our numerical investigations of the full set of cold fluid equations go beyond the usual weak nonlinearity approximation and show the existence of a rich variety of solutions including wakes, precursor solitons, and “pinned” solitons that travel with the source velocity. These solutions represent a large amplitude generalization of solutions obtained in the past for the forced Korteweg deVries equation and can find useful applications in a variety of situations in the laboratory and in space, wherever there is a largemore » relative velocity between the plasma and a charged object.« less

Determination of thermal properties of commercial Ni-MH cells

NASA Technical Reports Server (NTRS)

Darcy, Eric C.

1994-01-01

The test objectives were to evaluate the electrical and thermal performance of commercial Ni-MH cells, evaluate the effectiveness of commercial charge control circuits, assess the abuse tolerance of these cells, and correlate performance and abuse tolerances to cell design via disassembly. Design objectives were to determine which cell designs are most suitable for scale-up and to guide the design of future shuttle and space station based battery chargers. Results, displayed in viewgraph format, include: reflex charging with ICS circuit resulted in premature charge termination; Ni-MH cells appear very tolerant to overcharge at low rates; Enstore's charger is more electrically and thermally efficient at high rates; and Ni-MH cycles much more efficiently than Ni-Cd with the delta-V/delta-t termination.

Concept for a commercial space station laboratory

NASA Technical Reports Server (NTRS)

Wood, P. W.; Stark, P. M.

1984-01-01

The concept of a privately owned and operated fee-for-service laboratory as an element of a civil manned space station, envisioned as the venture of a group of private investors and an experienced laboratory operator to be undertaken with the cooperation of NASA is discussed. This group would acquire, outfit, activate, and operate the labortory on a fee-for-service basis, providing laboratory services to commercial firms, universities, and government agencies, including NASA. This concept was developed to identify, stimulate, and assist potential commercial users of a manned space station. A number of the issues which would be related to the concept, including the terms under which NASA might consider permitting private ownership and operation of a major space station component, the policies with respect to international participation in the construction and use of the space station, the basis for charging users for services received from the space station, and the types of support that NASA might be willing to provide to assist private industry in carrying out such a venture are discussed.

Reformulated space-charge-limited current model and its application to disordered organic systems

NASA Astrophysics Data System (ADS)

Woellner, Cristiano F.; Freire, José A.

2011-02-01

We have reformulated a traditional model used to describe the current-voltage dependence of low mobility materials sandwiched between planar electrodes by using the quasi-electrochemical potential as the fundamental variable instead of the local electric field or the local charge carrier density. This allows the material density-of-states to enter explicitly in the equations and dispenses with the need to assume a particular type of contact. The diffusion current is included and as a consequence the current-voltage dependence obtained covers, with increasing bias, the diffusion limited current, the space-charge limited current, and the injection limited current regimes. The generalized Einstein relation and the field and density dependent mobility are naturally incorporated into the formalism; these two points being of particular relevance for disordered organic semiconductors. The reformulated model can be applied to any material where the carrier density and the mobility may be written as a function of the quasi-electrochemical potential. We applied it to the textbook example of a nondegenerate, constant mobility material and showed how a single dimensionless parameter determines the form of the I(V) curve. We obtained integral expressions for the carrier density and for the mobility as a function of the quasi-electrochemical potential for a Gaussianly disordered organic material and found the general form of the I(V) curve for such materials over the full range of bias, showing how the energetic disorder alone can give rise, in the space-charge limited current regime, to an I∝Vn dependence with an exponent n larger than 2.

Applications of particle microbeams in space radiation research.

PubMed

Durante, Marco

2009-03-01

Galactic cosmic radiation is acknowledged as one of the major barriers to human space exploration. In space, astronauts are exposed to charged particles from Z = 1 (H) up to Z = 28 (Ni), but the probability of a hit to a specific single cell in the human body is low. Particle microbeams can deliver single charged particles of different charge and energy to single cells from different tissues, and microbeam studies are therefore very useful for improving current risk estimates for long-term space travel. 2D in vitro cell cultures can be very useful for establishing basic molecular mechanisms, but they are not sufficient to extrapolate risk, given the substantial evidence proving tissue effects are key in determining the response to radiation insult. 3D tissue or animal systems represent a more promising target for space radiobiology using microbeams.

Optimization for Single-Spike X-Ray FELs at LCLS with a Low Charge Beam

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

Wang, L.; Ding, Y.; Huang, Z.

2011-12-14

The Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron radiation sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup at 20 pC charge. In the soft x-ray regime, with combination of slotted-foil or undulator taper, a single spike x-ray pulse is achievablemore » with peak FEL power of a few 10s GW. Linac Coherent Light Source (LCLS), the world's first hard x-ray Free electron laser (FEL), has started operation since 2009. With nominal operation charge of 250 pC, the generated x-ray pulse length is from 70 fs to a few hundred fs. This marks the beginning of a new era of ultrashort x-ray sciences. In addition, a low charge (20pC) operation mode has also been established. Since the collective effects are reduced at the low charge mode, we can increase the compression factor and still achieve a few kA peak current. The expected electron beam and x-ray pulses are less than 10 fs. There are growing interests in even shorter x-ray pulses, such as fs to sub-fs regime. One of the simple solutions is going to even lower charge. As discussed, single-spike x-ray pulses can be generated using 1 pC charge. However, this charge level is out of the present LCLS diagnostic range. 20 pC is a reasonable operation charge at LCLS, based on the present diagnostic system. At 20 pC in the soft x-ray wavelength regime, we have experimentally demonstrated that FEL can work at undercompression or over-compression mode, such as 1 degree off the full-compression; at full-compression, however, there is almost no lasing. In hard x-ray wavelength regime, we observed that there are reasonable photons generated even at full-compression mode, although the photon number is less than that from under-compression or over-compression mode. Since we cannot measure the x-ray pulse length at this time scale, the machine is typically optimized for generating maximum photons, not minimum pulse length. In this paper, we study the methods of producing femtosecond (or single-spike) x-ray pulses at LCLS with 20 pC charge, based on start-to-end simulations. Figure 1 shows a layout of LCLS. The compression in the second bunch compressor (BC2) determines the final e-beam bunch length. However, the laser heater, dog-leg after the main linac (DL2) and collective effects also affect the final bunch length. To adjust BC2 compression, we can either change the L2 phase or BC2 R{sub 56}. In this paper we only tune L2 phase while keep BC2 R{sub 56} fixed. For the start-to-end simulations, we used IMPACT-T and ELEGANT tracking from the photocathode to the entrance of the undulator, after that the FEL radiation was simulated with GENESIS. IMPACT-T tracks about 10{sup 6} particles in the injector part until 135 MeV, including 3D space charge force. The output particles from IMPACT-T are smoothed and increased to 12 x 10{sup 6} to reduce high-frequency numerical noise for subsequent ELEGANT simulations, which include linear and nonlinear transport effects, a 1D transient model of CSR, and longitudinal space charge effects, as well as geometric and resistive wake fields in the accelerator. In GENESIS part, the longitudinal wake field from undulator chamber and longitudinal space field are also included.« less

Charge retention test experiences on Hubble Space Telescope nickel-hydrogen battery cells

NASA Technical Reports Server (NTRS)

Nawrocki, Dave E.; Driscoll, J. R.; Armantrout, J. D.; Baker, R. C.; Wajsgras, H.

1993-01-01

The Hubble Space Telescope (HST) nickel-hydrogen battery module was designed by Lockheed Missile & Space Co (LMSC) and manufactured by Eagle-Picher Ind. (EPI) for the Marshall Space Flight Center (MSFC) as an Orbital Replacement Unit (ORU) for the nickel-cadmium batteries originally selected for this low earth orbit mission. The design features of the HST nickel hydrogen battery are described and the results of an extended charge retention test are summarized.

Development of CCD imaging sensors for space applications, phase 1

NASA Technical Reports Server (NTRS)

Antcliffe, G. A.

1975-01-01

The results of an experimental investigation to develop a large area charge coupled device (CCD) imager for space photography applications are described. Details of the design and processing required to achieve 400 X 400 imagers are presented together with a discussion of the optical characterization techniques developed for this program. A discussion of several aspects of large CCD performance is given with detailed test reports. The areas covered include dark current, uniformity of optical response, square wave amplitude response, spectral responsivity and dynamic range.

Carrier transport and collection in fully depleted semiconductors by a combined action of the space charge field and the field due to electrode voltages

DOEpatents

Rehak, P.; Gatti, E.

1984-02-24

A semiconductor charge transport device and method for making same, characterized by providing a thin semiconductor wafer having rectifying functions on its opposing major surfaces and including a small capacitance ohmic contact, in combination with bias voltage means and associated circuit means for applying a predetermined voltage to effectively deplete the wafer in regions thereof between the rectifying junctions and the ohmic contact. A charge transport device of the invention is usable as a drift chamber, a low capacitance detector, or a charge coupled device each constructed according to the methods of the invention for making such devices. Detectors constructed according to the principles of the invention are characterized by having significantly higher particle position indicating resolution than is attainable with prior art detectors, while at the same time requiring substantially fewer readout channels to realize such high resolution.

Carrier transport and collection in fully depleted semiconductors by a combined action of the space charge field and the field due to electrode voltages

DOEpatents

Rehak, Pavel; Gatti, Emilio

1987-01-01

A semiconductor charge transport device and method for making same, characterized by providing a thin semiconductor wafer having rectifying junctions on its opposing major surfaces and including a small capacitance ohmic contact, in combination with bias voltage means and associated circuit means for applying a predetermined voltage to effectively deplete the wafer in regions thereof between the rectifying junctions and the ohmic contact. A charge transport device of the invention is usable as a drift chamber, a low capacitance detector, or a charge coupled device each constructed according to the methods of the invention for making such devices. Detectors constructed according to the principles of the invention are characterized by having significantly higher particle position indicating resolution than is attainable with prior art detectors, while at the same time requiring substantially fewer readout channels to realize such high resolution.

Carrier transport and collection in fully depleted semiconductors by a combined action of the space charge field and the field due to electrode voltages

DOEpatents

Rehak, P.; Gatti, E.

1987-08-18

A semiconductor charge transport device and method for making same are disclosed, characterized by providing a thin semiconductor wafer having rectifying junctions on its opposing major surfaces and including a small capacitance ohmic contact, in combination with bias voltage means and associated circuit means for applying a predetermined voltage to effectively deplete the wafer in regions thereof between the rectifying junctions and the ohmic contact. A charge transport device of the invention is usable as a drift chamber, a low capacitance detector, or a charge coupled device each constructed according to the methods of the invention for making such devices. Detectors constructed according to the principles of the invention are characterized by having significantly higher particle position indicating resolution than is attainable with prior art detectors, while at the same time requiring substantially fewer readout channels to realize such high resolution. 16 figs.

Analytical model of secondary electron emission yield in electron beam irradiated insulators.

PubMed

Ghorbel, N; Kallel, A; Damamme, G

2018-06-12

The study of secondary electron emission (SEE) yield as a function of the kinetic energy of the incident primary electron beam and its evolution with charge accumulation inside insulators is a source of valuable information (even though an indirect one) on charge transport and trapping phenomena. We will show that this evolution is essentially due, in plane geometry conditions (achieved using a defocused electron beam), to the electric field effect (due to the accumulation of trapped charges in the bulk) in the escape zone of secondary electrons and not to modifications of trapping cross sections, which only have side effects. We propose an analytical model including the main basic phenomena underlying the space charge dynamics. It will be observed that such a model makes it possible to reproduce both qualitatively and quantitatively the measurement of SEE evolution as well as to provide helpful indications concerning charge transport (more precisely, the ratios between the mobility and diffusion coefficient with the thermal velocity of the charge carrier). Copyright © 2018 Elsevier Ltd. All rights reserved.

Charge Storage, Conductivity and Charge Profiles of Insulators as Related to Spacecraft Charging

NASA Technical Reports Server (NTRS)

Dennison, J. R.; Swaminathan, Prasanna; Frederickson, A. R.

2004-01-01

Dissipation of charges built up near the surface of insulators due to space environment interaction is central to understanding spacecraft charging. Conductivity of insulating materials is key to determine how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. To understand these processes requires knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and charge transport within the insulator, and how the profile of trapped charge affects the transport and emission of charges from insulators. One must consider generation of mobile electrons and holes, their trapping, thermal de-trapping, mobility and recombination. Conductivity is more appropriately measured for spacecraft charging applications as the "decay" of charge deposited on the surface of an insulator, rather than by flow of current across two electrodes around the sample. We have found that conductivity determined from charge storage decay methods is 102 to 104 smaller than values obtained from classical ASTM and IEC methods for a variety of thin film insulating samples. For typical spacecraft charging conditions, classical conductivity predicts decay times on the order of minutes to hours (less than typical orbit periods); however, the higher charge storage conductivities predict decay times on the order of weeks to months leading to accumulation of charge with subsequent orbits. We found experimental evidence that penetration profiles of radiation and light are exceedingly important, and that internal electric fields due to charge profiles and high-field conduction by trapped electrons must be considered for space applications. We have also studied whether the decay constants depend on incident voltage and flux or on internal charge distributions and electric fields; light-activated discharge of surface charge to distinguish among differing charge trapping centers; and radiation-induced conductivity. Our experiments also show that "Malter" electron emission occurs for hours after turning off the electron beam. This Malter emission similar to emission due to negative electron affinity in semiconductors is a result of the prior radiation or optical excitations of valence electrons and their slow drift among traps towards the surface where they are subsequently emitted. This work is supported through funding from the NASA Space Environments and Effects Program.

Comparison of Classical and Charge Storage Methods for Determining Conductivity of Thin Film Insulators

NASA Technical Reports Server (NTRS)

Swaminathan, Prasanna; Dennison, J. R.; Sim, Alec; Brunson, Jerilyn; Crapo, Eric; Frederickson, A. R.

2004-01-01

Conductivity of insulating materials is a key parameter to determine how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. Classical ASTM and IEC methods to measure thin film insulator conductivity apply a constant voltage to two electrodes around the sample and measure the resulting current for tens of minutes. However, conductivity is more appropriately measured for spacecraft charging applications as the "decay" of charge deposited on the surface of an insulator. Charge decay methods expose one side of the insulator in vacuum to sequences of charged particles, light, and plasma, with a metal electrode attached to the other side of the insulator. Data are obtained by capacitive coupling to measure both the resulting voltage on the open surface and emission of electrons from the exposed surface, as well monitoring currents to the electrode. Instrumentation for both classical and charge storage decay methods has been developed and tested at Jet Propulsion Laboratory (JPL) and at Utah State University (USU). Details of the apparatus, test methods and data analysis are given here. The JPL charge storage decay chamber is a first-generation instrument, designed to make detailed measurements on only three to five samples at a time. Because samples must typically be tested for over a month, a second-generation high sample throughput charge storage decay chamber was developed at USU with the capability of testing up to 32 samples simultaneously. Details are provided about the instrumentation to measure surface charge and current; for charge deposition apparatus and control; the sample holders to properly isolate the mounted samples; the sample carousel to rotate samples into place; the control of the sample environment including sample vacuum, ambient gas, and sample temperature; and the computer control and data acquisition systems. Measurements are compared here for a number of thin film insulators using both methods at both facilities. We have found that conductivity determined from charge storage decay methods is 102 to 104 larger than values obtained from classical methods. Another Spacecraft Charging Conference presentation describes more extensive measurements made with these apparatus. This work is supported through funding from the NASA Space Environments and Effects Program and the USU Space Dynamics Laboratory Enabling Technologies Program.

Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder

NASA Astrophysics Data System (ADS)

Armano, M.; Audley, H.; Auger, G.; Baird, J. T.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Bursi, A.; Caleno, M.; Cavalleri, A.; Cesarini, A.; Cruise, M.; Danzmann, K.; de Deus Silva, M.; Diepholz, I.; Dolesi, R.; Dunbar, N.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Flatscher, R.; Freschi, M.; Gallegos, J.; García Marirrodriga, C.; Gerndt, R.; Gesa, L.; Gibert, F.; Giardini, D.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hueller, M.; Huesler, J.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Kaune, B.; Killow, C. J.; Korsakova, N.; Lloro, I.; Liu, L.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Madden, S.; Mance, D.; Martín, V.; Martin-Polo, L.; Martino, J.; Martin-Porqueras, F.; Mateos, I.; McNamara, P. W.; Mendes, J.; Mendes, L.; Moroni, A.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Pivato, P.; Plagnol, E.; Prat, P.; Ragnit, U.; Ramos-Castro, J.; Reiche, J.; Romera Perez, J. A.; Robertson, D. I.; Rozemeijer, H.; Rivas, F.; Russano, G.; Sarra, P.; Schleicher, A.; Slutsky, J.; Sopuerta, C.; Sumner, T. J.; Texier, D.; Thorpe, J. I.; Trenkel, C.; Vetrugno, D.; Vitale, S.; Wanner, G.; Ward, H.; Wass, P. J.; Wealthy, D.; Weber, W. J.; Wittchen, A.; Zanoni, C.; Ziegler, T.; Zweifel, P.; LISA Pathfinder Collaboration

2017-04-01

We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0 fm s-2 Hz-1 /2 across the 0.1-100 mHz frequency band that is crucial to an observatory such as the Laser Interferometer Space Antenna (LISA). Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge buildup due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument.

Atomic Radius and Charge Parameter Uncertainty in Biomolecular Solvation Energy Calculations

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

Yang, Xiu; Lei, Huan; Gao, Peiyuan

Atomic radii and charges are two major parameters used in implicit solvent electrostatics and energy calculations. The optimization problem for charges and radii is under-determined, leading to uncertainty in the values of these parameters and in the results of solvation energy calculations using these parameters. This paper presents a method for quantifying this uncertainty in solvation energies using surrogate models based on generalized polynomial chaos (gPC) expansions. There are relatively few atom types used to specify radii parameters in implicit solvation calculations; therefore, surrogate models for these low-dimensional spaces could be constructed using least-squares fitting. However, there are many moremore » types of atomic charges; therefore, construction of surrogate models for the charge parameter space required compressed sensing combined with an iterative rotation method to enhance problem sparsity. We present results for the uncertainty in small molecule solvation energies based on these approaches. Additionally, we explore the correlation between uncertainties due to radii and charges which motivates the need for future work in uncertainty quantification methods for high-dimensional parameter spaces.« less

Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder.

PubMed

Armano, M; Audley, H; Auger, G; Baird, J T; Binetruy, P; Born, M; Bortoluzzi, D; Brandt, N; Bursi, A; Caleno, M; Cavalleri, A; Cesarini, A; Cruise, M; Danzmann, K; de Deus Silva, M; Diepholz, I; Dolesi, R; Dunbar, N; Ferraioli, L; Ferroni, V; Fitzsimons, E D; Flatscher, R; Freschi, M; Gallegos, J; García Marirrodriga, C; Gerndt, R; Gesa, L; Gibert, F; Giardini, D; Giusteri, R; Grimani, C; Grzymisch, J; Harrison, I; Heinzel, G; Hewitson, M; Hollington, D; Hueller, M; Huesler, J; Inchauspé, H; Jennrich, O; Jetzer, P; Johlander, B; Karnesis, N; Kaune, B; Killow, C J; Korsakova, N; Lloro, I; Liu, L; López-Zaragoza, J P; Maarschalkerweerd, R; Madden, S; Mance, D; Martín, V; Martin-Polo, L; Martino, J; Martin-Porqueras, F; Mateos, I; McNamara, P W; Mendes, J; Mendes, L; Moroni, A; Nofrarias, M; Paczkowski, S; Perreur-Lloyd, M; Petiteau, A; Pivato, P; Plagnol, E; Prat, P; Ragnit, U; Ramos-Castro, J; Reiche, J; Romera Perez, J A; Robertson, D I; Rozemeijer, H; Rivas, F; Russano, G; Sarra, P; Schleicher, A; Slutsky, J; Sopuerta, C; Sumner, T J; Texier, D; Thorpe, J I; Trenkel, C; Vetrugno, D; Vitale, S; Wanner, G; Ward, H; Wass, P J; Wealthy, D; Weber, W J; Wittchen, A; Zanoni, C; Ziegler, T; Zweifel, P

2017-04-28

We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0  fm s^{-2} Hz^{-1/2} across the 0.1-100 mHz frequency band that is crucial to an observatory such as the Laser Interferometer Space Antenna (LISA). Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge buildup due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument.

Time-resolved correlative optical microscopy of charge-carrier transport, recombination, and space-charge fields in CdTe heterostructures

DOE PAGES

Kuciauskas, Darius; Myers, Thomas H.; Barnes, Teresa M.; ...

2017-02-20

From time- and spatially resolved optical measurements, we show that extended defects can have a large effect on the charge-carrier recombination in II-VI semiconductors. In CdTe double heterostructures grown by molecular beam epitaxy on the InSb (100)-orientation substrates, we characterized the extended defects and found that near stacking faults the space-charge field extends by 2-5 μm. Charge carriers drift (with the space-charge field strength of 730-1,360 V cm -1) and diffuse (with the mobility of 260 ± 30 cm 2 V -1 s -1) toward the extended defects, where the minority-carrier lifetime is reduced from 560 ns to 0.25 ns.more » Furthermore, the extended defects are nonradiative recombination sinks that affect areas significantly larger than the typical crystalline grains in II-VI solar cells. From the correlative time-resolved photoluminescence and second-harmonic generation microscopy data, we developed a band-diagram model that can be used to analyze the impact of extended defects on solar cells and other electronic devices.« less

Operating in the space plasma environment: A spacecraft charging study of the Solar X-ray Imager

NASA Technical Reports Server (NTRS)

Herr, Joel L.; Mccollum, Matthew B.; James, Bonnie F.

1994-01-01

This study presents the results of a spacecraft charging effects protection study conducted on the Solar X-ray Imager (SXI). The SXI is being developed by NASA Marshall Space Flight Center for NOAA's Space Environment Laboratory, and will be used to aid in forecasting energetic particle events and geomagnetic storms. Images will provide information on the intensity and location of solar flares, coronal mass ejections, and high speed solar streams. The SXI will be flown on a next-generation GOES sometime in the mid to late 1990's. Charging due to the encounter with a worst-case magnetic substorm environment is modeled using the NASCAP/GEO computer code. Charging levels of exterior surfaces and the floating potential of the spacecraft relative to plasma are determined as a function of spacecraft design, operational configuration, and orbital conditions. Areas where large surface voltage gradients exist on or near the SXI are identified as possible arc-discharge sites. Results of the charging analysis are then used to develop design recommendations that will limit the effects of spacecraft charging on the SXI operation.

Non-Faradaic Li + Migration and Chemical Coordination across Solid-State Battery Interfaces

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

Gittleson, Forrest S.; El Gabaly, Farid

Efficient and reversible charge transfer is essential to realizing high-performance solid-state batteries. Efforts to enhance charge transfer at critical electrode–electrolyte interfaces have proven successful, yet interfacial chemistry and its impact on cell function remains poorly understood. Using X-ray photoelectron spectroscopy combined with electrochemical techniques, we elucidate chemical coordination near the LiCoO 2–LIPON interface, providing experimental validation of space-charge separation. Space-charge layers, defined by local enrichment and depletion of charges, have previously been theorized and modeled, but the unique chemistry of solid-state battery interfaces is now revealed. Here we highlight the non-Faradaic migration of Li+ ions from the electrode to themore » electrolyte, which reduces reversible cathodic capacity by ~15%. Inserting a thin, ion-conducting LiNbO 3 interlayer between the electrode and electrolyte, however, can reduce space-charge separation, mitigate the loss of Li+ from LiCoO 2, and return cathodic capacity to its theoretical value. This work illustrates the importance of interfacial chemistry in understanding and improving solid-state batteries.« less

Time-resolved correlative optical microscopy of charge-carrier transport, recombination, and space-charge fields in CdTe heterostructures

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

Kuciauskas, Darius; Myers, Thomas H.; Barnes, Teresa M.

From time- and spatially resolved optical measurements, we show that extended defects can have a large effect on the charge-carrier recombination in II-VI semiconductors. In CdTe double heterostructures grown by molecular beam epitaxy on the InSb (100)-orientation substrates, we characterized the extended defects and found that near stacking faults the space-charge field extends by 2-5 μm. Charge carriers drift (with the space-charge field strength of 730-1,360 V cm -1) and diffuse (with the mobility of 260 ± 30 cm 2 V -1 s -1) toward the extended defects, where the minority-carrier lifetime is reduced from 560 ns to 0.25 ns.more » Furthermore, the extended defects are nonradiative recombination sinks that affect areas significantly larger than the typical crystalline grains in II-VI solar cells. From the correlative time-resolved photoluminescence and second-harmonic generation microscopy data, we developed a band-diagram model that can be used to analyze the impact of extended defects on solar cells and other electronic devices.« less

The Planeterrella: an Analog Model for Teaching About the Invisible Electromagnetic Processes Driving Space Weather

NASA Astrophysics Data System (ADS)

Masongsong, E. V.; Glesener, G. B.; Angelopoulos, V.; Lilensten, J.; Bingley, L.

2015-12-01

The Planeterrella can be used as an analog to help students visualize and understand the electromagnetic processes driving space weather that affect our daily lives. Solar storms and solar wind charged particles (plasma) cause "space weather" via their interaction with Earth's protective magnetic shield, the magnetosphere. The Planeterrella uses magnetized spheres in a vacuum chamber to demonstrate solar wind energy transfer to Earth and planets, with polar localization of aurora due to charged particles traveling along geomagnetic field lines. The Planeterrella provides a unique opportunity to experience and manipulate plasma, the dominant form of matter in our universe, yet seldom observable on Earth. Severe space weather events produce spectacular auroral displays as well as devastating consequences: radiation exposure to air and space travelers, prolonged radio blackouts, and damage to critical GPS and communications satellites. We will (1) discuss ways in which the Planeterrella may be most useful in classroom settings, including large lecture halls, laboratories, and small discussion sessions; (2) provide information on how instructors can produce their own Planeterrella for their courses; and (3) invite meeting attendees to engage in a discussion on how we might be able to improve on the current design of the Planeterrella, and how to reach students in more parts of the world.

Research-to-operations (R2O) for the Space Environmental Effects Fusion System (SEEFS) system-impact products

NASA Astrophysics Data System (ADS)

Quigley, Stephen

The Space Vehicles Directorate of the Air Force Research Laboratory (AFRL/RVBX) and the Space Environment Branch of the Space and Missile Systems Center (SMC SLG/WMLE) have combined efforts to design, develop, test, implement, and validate numerical and graphical products for Air Force Space Command's (AFSPC) Space Environmental Effects Fusion System (SEEFS). These products are generated to analyze, specify, and forecast the effects of the near-earth space environment on Department of Defense weapons, navigation, communications, and surveillance systems. Jointly developed projects that have been completed as prototypes and are undergoing development for real-time operations include a SEEFS architecture and database, five system-impact products, and a high-level decision aid product. This first round of SEEFS products includes the Solar Radio Burst Effects (SoRBE) on radar and satellite communications, Radar Auroral Clutter (RAC), Scintillation Effects on radar and satellite communications (RadScint and SatScint), and Satellite Surface and Deep Charge/Discharge (Char/D) products. This presentation will provide overviews of the current system impact products, along with plans and potentials for future products expected for the SEEFS program. The overviews will include information on applicable research-to-operations (R2O) issues, to include input data coverage and quality control, output confidence levels, modeling standards, and validation efforts.

Charged dust phenomena in the near-Earth space environment.

PubMed

Scales, W A; Mahmoudian, A

2016-10-01

Dusty (or complex) plasmas in the Earth's middle and upper atmosphere ultimately result in exotic phenomena that are currently forefront research issues in the space science community. This paper presents some of the basic criteria and fundamental physical processes associated with the creation, evolution and dynamics of dusty plasmas in the near-Earth space environment. Recent remote sensing techniques to probe naturally created dusty plasma regions are also discussed. These include ground-based experiments employing high-power radio wave interaction. Some characteristics of the dusty plasmas that are actively produced by space-borne aerosol release experiments are discussed. Basic models that may be used to investigate the characteristics of such dusty plasma regions are presented.

Space and Atmospheric Environments: From Low Earth Orbits to Deep Space

NASA Technical Reports Server (NTRS)

Barth, Janet L.

2003-01-01

Natural space and atmospheric environments pose a difficult challenge for designers of technological systems in space. The deleterious effects of environment interactions with the systems include degradation of materials, thermal changes, contamination, excitation, spacecraft glow, charging, radiation damage, and induced background interference. Design accommodations must be realistic with minimum impact on performance while maintaining a balance between cost and risk. The goal of applied research in space environments and effects is to limit environmental impacts at low cost relative to spacecraft cost and to infuse enabling and commercial off-the-shelf technologies into space programs. The need to perform applied research to understand the space environment in a practical sense and to develop methods to mitigate these environment effects is frequently underestimated by space agencies and industry. Applied science research in this area is critical because the complexity of spacecraft systems is increasing, and they are exposed simultaneously to a multitude of space environments.

Finite-element 3D simulation tools for high-current relativistic electron beams

NASA Astrophysics Data System (ADS)

Humphries, Stanley; Ekdahl, Carl

2002-08-01

The DARHT second-axis injector is a challenge for computer simulations. Electrons are subject to strong beam-generated forces. The fields are fully three-dimensional and accurate calculations at surfaces are critical. We describe methods applied in OmniTrak, a 3D finite-element code suite that can address DARHT and the full range of charged-particle devices. The system handles mesh generation, electrostatics, magnetostatics and self-consistent particle orbits. The MetaMesh program generates meshes of conformal hexahedrons to fit any user geometry. The code has the unique ability to create structured conformal meshes with cubic logic. Organized meshes offer advantages in speed and memory utilization in the orbit and field solutions. OmniTrak is a versatile charged-particle code that handles 3D electric and magnetic field solutions on independent meshes. The program can update both 3D field solutions from the calculated beam space-charge and current-density. We shall describe numerical methods for orbit tracking on a hexahedron mesh. Topics include: 1) identification of elements along the particle trajectory, 2) fast searches and adaptive field calculations, 3) interpolation methods to terminate orbits on material surfaces, 4) automatic particle generation on multiple emission surfaces to model space-charge-limited emission and field emission, 5) flexible Child law algorithms, 6) implementation of the dual potential model for 3D magnetostatics, and 7) assignment of charge and current from model particle orbits for self-consistent fields.

Active control of bright electron beams with RF optics for femtosecond microscopy

DOE PAGES

Williams, J.; Zhou, F.; Sun, T.; ...

2017-08-01

A frontier challenge in implementing femtosecond electron microscopy is to gain precise optical control of intense beams to mitigate collective space charge effects for significantly improving the throughput. In this paper, we explore the flexible uses of an RF cavity as a longitudinal lens in a high-intensity beam column for condensing the electron beams both temporally and spectrally, relevant to the design of ultrafast electron microscopy. Through the introduction of a novel atomic grating approach for characterization of electron bunch phase space and control optics, we elucidate the principles for predicting and controlling the phase space dynamics to reach optimalmore » compressions at various electron densities and generating conditions. We provide strategies to identify high-brightness modes, achieving ~100 fs and ~1 eV resolutions with 10 6 electrons per bunch, and establish the scaling of performance for different bunch charges. These results benchmark the sensitivity and resolution from the fundamental beam brightness perspective and also validate the adaptive optics concept to enable delicate control of the density-dependent phase space structures to optimize the performance, including delivering ultrashort, monochromatic, high-dose, or coherent electron bunches.« less

HZETRN: Description of a free-space ion and nucleon transport and shielding computer program

NASA Technical Reports Server (NTRS)

Wilson, John W.; Badavi, Francis F.; Cucinotta, Francis A.; Shinn, Judy L.; Badhwar, Gautam D.; Silberberg, R.; Tsao, C. H.; Townsend, Lawrence W.; Tripathi, Ram K.

1995-01-01

The high-charge-and energy (HZE) transport computer program HZETRN is developed to address the problems of free-space radiation transport and shielding. The HZETRN program is intended specifically for the design engineer who is interested in obtaining fast and accurate dosimetric information for the design and construction of space modules and devices. The program is based on a one-dimensional space-marching formulation of the Boltzmann transport equation with a straight-ahead approximation. The effect of the long-range Coulomb force and electron interaction is treated as a continuous slowing-down process. Atomic (electronic) stopping power coefficients with energies above a few A MeV are calculated by using Bethe's theory including Bragg's rule, Ziegler's shell corrections, and effective charge. Nuclear absorption cross sections are obtained from fits to quantum calculations and total cross sections are obtained with a Ramsauer formalism. Nuclear fragmentation cross sections are calculated with a semiempirical abrasion-ablation fragmentation model. The relation of the final computer code to the Boltzmann equation is discussed in the context of simplifying assumptions. A detailed description of the flow of the computer code, input requirements, sample output, and compatibility requirements for non-VAX platforms are provided.

Active control of bright electron beams with RF optics for femtosecond microscopy

PubMed Central

Williams, J.; Zhou, F.; Sun, T.; Tao, Z.; Chang, K.; Makino, K.; Berz, M.; Duxbury, P. M.; Ruan, C.-Y.

2017-01-01

A frontier challenge in implementing femtosecond electron microscopy is to gain precise optical control of intense beams to mitigate collective space charge effects for significantly improving the throughput. Here, we explore the flexible uses of an RF cavity as a longitudinal lens in a high-intensity beam column for condensing the electron beams both temporally and spectrally, relevant to the design of ultrafast electron microscopy. Through the introduction of a novel atomic grating approach for characterization of electron bunch phase space and control optics, we elucidate the principles for predicting and controlling the phase space dynamics to reach optimal compressions at various electron densities and generating conditions. We provide strategies to identify high-brightness modes, achieving ∼100 fs and ∼1 eV resolutions with 106 electrons per bunch, and establish the scaling of performance for different bunch charges. These results benchmark the sensitivity and resolution from the fundamental beam brightness perspective and also validate the adaptive optics concept to enable delicate control of the density-dependent phase space structures to optimize the performance, including delivering ultrashort, monochromatic, high-dose, or coherent electron bunches. PMID:28868325

The ESA Space Environment Information System (SPENVIS)

NASA Astrophysics Data System (ADS)

Heynderickx, D.; Quaghebeur, B.; Evans, H. D. R.

2002-01-01

The ESA SPace ENVironment Information System (SPENVIS) provides standardized access to models of the hazardous space environment through a user-friendly WWW interface. The interface includes parameter input with extensive defaulting, definition of user environments, streamlined production of results (both in graphical and textual form), background information, and on-line help. It is available on-line at http://www.spenvis.oma.be/spenvis/. SPENVIS Is designed to help spacecraft engineers perform rapid analyses of environmental problems and, with extensive documentation and tutorial information, allows engineers with relatively little familiarity with the models to produce reliable results. It has been developed in response to the increasing pressure for rapid-response tools for system engineering, especially in low-cost commercial and educational programmes. It is very useful in conjunction with radiation effects and electrostatic charging testing in the context of hardness assurance. SPENVIS is based on internationally recognized standard models and methods in many domains. It uses an ESA-developed orbit generator to produce orbital point files necessary for many different types of problem. It has various reporting and graphical utilities, and extensive help facilities. The SPENVIS radiation module features models of the proton and electron radiation belts, as well as solar energetic particle and cosmic ray models. The particle spectra serve as input to models of ionising dose (SHIELDOSE), Non-Ionising Energy Loss (NIEL), and Single Event Upsets (CREME). Material shielding is taken into account for all these models, either as a set of user-defined shielding thicknesses, or in combination with a sectoring analysis that produces a shielding distribution from a geometric description of the satellite system. A sequence of models, from orbit generator to folding dose curves with a shielding distribution, can be run as one process, which minimizes user interaction and facilitates multiple runs with different orbital or shielding configurations. SPENVIS features a number of models and tools for evaluating spacecraft charging. The DERA DICTAT tool for evaluation of internal charging calculates the electron current that passes through a conductive shield and becomes deposited inside a dielectric, and predicts whether an electrostatic discharge will occur. SPENVIS has implemented the DERA EQUIPOT non-geometrical tool for assessing material susceptibility to charging in typical orbital environments, including polar and GEO environments. SPENVIS Also includes SOLARC, for assessment of the current collection and the floating potential of solar arrays in LEO. Finally, the system features access to data from surface charging events on CRRES and the Russian Gorizont spacecraft, in the form of spectrograms and double Maxwellian fit parameters. SPENVIS also contains an active, integrated version of the ECSS Space Environment Standard, and access to in-flight data. Apart from radiation and plasma environments, SPENVIS includes meteoroid and debris models, atmospheric models (including atomic oxygen), and magnetic field models implemented by means of the UNILIB library for magnetic coordinate evaluation, magnetic field line tracing and drift shell tracing. The UNILIB library is freely accessible from the Web (http://www.magnet.oma.be/unilib/) for downloading in the form of a Fortran object library for different platforms (DecAlpha, SunOS, HPUX and PC/MS-Windows).

Real-space measurement of potential distribution in PECVD ONO electrets by Kelvin probe force microscopy.

PubMed

Emmerich, F; Thielemann, C

2016-05-20

Multilayers of silicon oxide/silicon nitride/silicon oxide (ONO) are known for their good electret properties due to deep energy traps near the material interfaces, facilitating charge storage. However, measurement of the space charge distribution in such multilayers is a challenge for conventional methods if layer thickness dimensions shrink below 1 μm. In this paper, we propose an atomic force microscope based method to determine charge distributions in ONO layers with spatial resolution below 100 nm. By applying Kelvin probe force microscopy (KPFM) on freshly cleaved, corona-charged multilayers, the surface potential is measured directly along the z-axis and across the interfaces. This new method gives insights into charge distribution and charge movement in inorganic electrets with a high spatial resolution.

Inter-phase charge and energy transfer in Ruddlesden–Popper 2D perovskites: critical role of the spacing cations

DOE PAGES

Zheng, Kaibo; Chen, Yani; Sun, Yong; ...

2018-01-01

Photo-generated charge carrier dynamics in Ruddlesden–Popper 2D perovskites with linear ( n -BA) and branched (iso-BA) butylamine as spacing cations have been studied by using transient absorption and time-resolved photoluminescence spectroscopies.

Inter-phase charge and energy transfer in Ruddlesden–Popper 2D perovskites: critical role of the spacing cations

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

Zheng, Kaibo; Chen, Yani; Sun, Yong

Photo-generated charge carrier dynamics in Ruddlesden–Popper 2D perovskites with linear ( n -BA) and branched (iso-BA) butylamine as spacing cations have been studied by using transient absorption and time-resolved photoluminescence spectroscopies.

Adaptive matching of the iota ring linear optics for space charge compensation

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

Romanov, A.; Bruhwiler, D. L.; Cook, N.

Many present and future accelerators must operate with high intensity beams when distortions induced by space charge forces are among major limiting factors. Betatron tune depression of above approximately 0.1 per cell leads to significant distortions of linear optics. Many aspects of machine operation depend on proper relations between lattice functions and phase advances, and can be i proved with proper treatment of space charge effects. We implement an adaptive algorithm for linear lattice re matching with full account of space charge in the linear approximation for the case of Fermilab’s IOTA ring. The method is based on a searchmore » for initial second moments that give closed solution and, at the same predefined set of goals for emittances, beta functions, dispersions and phase advances at and between points of interest. Iterative singular value decomposition based technique is used to search for optimum by varying wide array of model parameters« less

Space charge effect in spectrometers of ion mobility increment with planar drift chamber.

PubMed

Elistratov, A A; Sherbakov, L A

2007-01-01

The effect of space charge on the ion beam in a spectrometer of ion mobility increment with the planar drift chamber has been investigated. A model for the drift of ions under a non-uniform high-frequency electric field(1-3) has been developed recently. We have amplified this model by taking space charge effect into account. The ion peak shape taking into consideration the space charge effect is obtained. The output current saturation effect limiting the rise of the ion peak with increasing ion density at the input of the drift chamber of a spectrometer is observed. We show that the saturation effect is caused by the following phenomenon. The maximum possible output ion density exists, depending on the ion type (constant ion mobility, k(0)) and the time of the motion of ions through the drift chamber. At the same time, the ion density does not depend on the parameters of the drift chamber.

Search for space charge effects in the ICARUS T600 LAr-TPC

NASA Astrophysics Data System (ADS)

Torti, Marta

2016-11-01

Space charge in Liquid Argon Time Projection Chamber is due to the accumu- lation of positive ions, produced by ionizing tracks crossing the detector, which slowly flow toward the cathode. As a consequence, electric field distortions may arise, thus hindering the possibility to produce faithful 3D images of the ionizing events. The presence of space charge becomes relevant for large TPCs operating at surface or at shallow depths, where cosmic ray flux is high. These effects could interest the next phase of the ICARUS T600 detector, which will be deployed at shallow depths as a Far Detector for Short Baseline Neutrino experiment at FNAL dedicated to sterile neutrino searches. In 2001, the first ICARUS T600 module (T300) operated at surface in Pavia (Italy), recording cosmic ray data. In this work, a sample of cosmic muon tracks from the 2001 run was analyzed and results on space charge effects in LAr-TPCs are shown.

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

Park, Chong Shik; Shiltsev, Vladimir; Stancari, Giulio

The ability to transport a high current proton beam in a ring is ultimately limited by space charge effects. Two novel ways to overcome this limit in a proton ring are by adding low energy, externally matched electron beams (electron lens, e-lens), and by taking advantage of residual gas ionization induced neutralization to create an electron column (e-column). Theory predicts that an appropriately confined electrons can completely compensate the space charge through neutralization, both transversely and longitudinally. In this report, we will discuss the current status of the Fermilab’s e-lens experiment for the space charge compensation. In addition, we willmore » show how the IOTA e-column compensates space charge with theWARP simulations. The dynamics of proton beams inside of the e-column is understood by changing the magnetic field of a solenoid, the voltage on the electrodes, and the vacuum pressure, and by looking for electron accumulation, as well as by considering various beam dynamics in the IOTA ring.« less

Space charge effects and aberrations on electron pulse compression in a spherical electrostatic capacitor.

PubMed

Yu, Lei; Li, Haibo; Wan, Weishi; Wei, Zheng; Grzelakowski, Krzysztof P; Tromp, Rudolf M; Tang, Wen-Xin

2017-12-01

The effects of space charge, aberrations and relativity on temporal compression are investigated for a compact spherical electrostatic capacitor (α-SDA). By employing the three-dimensional (3D) field simulation and the 3D space charge model based on numerical General Particle Tracer and SIMION, we map the compression efficiency for a wide range of initial beam size and single-pulse electron number and determine the optimum conditions of electron pulses for the most effective compression. The results demonstrate that both space charge effects and aberrations prevent the compression of electron pulses into the sub-ps region if the electron number and the beam size are not properly optimized. Our results suggest that α-SDA is an effective compression approach for electron pulses under the optimum conditions. It may serve as a potential key component in designing future time-resolved electron sources for electron diffraction and spectroscopy experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Simple phenomenological modeling of transition-region capacitance of forward-biased p-n junction diodes and transistor diodes

NASA Technical Reports Server (NTRS)

Lindholm, F. A.

1982-01-01

The derivation of a simple expression for the capacitance C(V) associated with the transition region of a p-n junction under a forward bias is derived by phenomenological reasoning. The treatment of C(V) is based on the conventional Shockley equations, and simpler expressions for C(V) result that are in general accord with the previous analytical and numerical results. C(V) consists of two components resulting from changes in majority carrier concentration and from free hole and electron accumulation in the space-charge region. The space-charge region is conceived as the intrinsic region of an n-i-p structure for a space-charge region markedly wider than the extrinsic Debye lengths at its edges. This region is excited in the sense that the forward bias creates hole and electron densities orders of magnitude larger than those in equilibrium. The recent Shirts-Gordon (1979) modeling of the space-charge region using a dielectric response function is contrasted with the more conventional Schottky-Shockley modeling.

Analytical and exact solutions of the spherical and cylindrical diodes of Langmuir-Blodgett law

NASA Astrophysics Data System (ADS)

Torres-Cordoba, Rafael; Martinez-Garcia, Edgar

2017-10-01

This paper discloses the exact solutions of a mathematical model that describes the cylindrical and spherical electron current emissions within the context of a physics approximation method. The solution involves analyzing the 1D nonlinear Poisson equation, for the radial component. Although an asymptotic solution has been previously obtained, we present a theoretical solution that satisfies arbitrary boundary conditions. The solution is found in its parametric form (i.e., φ(r )=φ(r (τ)) ) and is valid when the electric field at the cathode surface is non-zero. Furthermore, the non-stationary spatial solution of the electric potential between the anode and the cathode is also presented. In this work, the particle-beam interface is considered to be at the end of the plasma sheath as described by Sutherland et al. [Phys. Plasmas 12, 033103 2005]. Three regimes of space charge effects—no space charge saturation, space charge limited, and space charge saturation—are also considered.

Effects of polymer graft properties on protein adsorption and transport in ion exchange chromatography: a multiscale modeling study.

PubMed

Basconi, Joseph E; Carta, Giorgio; Shirts, Michael R

2015-04-14

Multiscale simulation is used to study the adsorption of lysozyme onto ion exchangers obtained by grafting charged polymers into a porous matrix, in systems with various polymer properties and strengths of electrostatic interaction. Molecular dynamics simulations show that protein partitioning into the polymer-filled pore space increases with the overall charge content of the polymers, while the diffusivity in the pore space decreases. However, the combination of greatly increased partitioning and modestly decreased diffusion results in macroscopic transport rates that increase as a function of charge content, as the large concentration driving force due to enhanced pore space partitioning outweighs the reduction in the pore space diffusivity. Matrices having greater charge associated with the grafted polymers also exhibit more diffuse intraparticle concentration profiles during transient adsorption. In systems with a high charge content per polymer and a low protein loading, the polymers preferentially partition toward the surface due to favorable interactions with the surface-bound protein. These results demonstrate the potential of multiscale modeling to illuminate qualitative trends between molecular properties and the adsorption equilibria and kinetic properties observable on macroscopic scales.

Electrical conductivity, dielectric response and space charge dynamics of an electroactive polymer with and without nanofiller reinforcement

NASA Astrophysics Data System (ADS)

Kochetov, R.; Tsekmes, I. A.; Morshuis, P. H. F.

2015-07-01

Electroactive polymers have gained considerable attention over the last 20 years for exhibiting a large displacement in response to electrical stimulation. The promising fields of application include wave energy converters, muscle-like actuators, sensors, robotics, and biomimetics. For an electrical engineer, electroactive polymers can be seen as a dielectric elastomer film or a compliant capacitor with a highly deformable elastomeric medium. If the elastomer is pre-stretched and pre-charged, a reduction of the tensile force lets the elastomer revert to its original form and increases the electrical potential. The light weight of electroactive polymers, low cost, high intrinsic breakdown strength, cyclical way of operation, reliable performance, and high efficiency can be exploited to utilize the elastomeric material as a transducer. The energy storage for a linear dielectric polymer is determined by its relative permittivity and the applied electric field. The latter is limited by the dielectric breakdown strength of the material. Therefore, to generate a high energy density of a flexible capacitor, the film must be used at the voltage level close to the material’s breakdown or inorganic particles with high dielectric permittivity which can be introduced into the polymer matrix. In the present study, silicone-titania elastomer nanocomposites were produced and the influence of nanoparticles on the macroscopic dielectric properties of the neat elastomer including space charge dynamics, complex permittivity, and electrical conductivity, were investigated.

Electrostatic plasma lens for focusing negatively charged particle beams.

PubMed

Goncharov, A A; Dobrovolskiy, A M; Dunets, S M; Litovko, I V; Gushenets, V I; Oks, E M

2012-02-01

We describe the current status of ongoing research and development of the electrostatic plasma lens for focusing and manipulating intense negatively charged particle beams, electrons, and negative ions. The physical principle of this kind of plasma lens is based on magnetic isolation electrons providing creation of a dynamical positive space charge cloud in shortly restricted volume propagating beam. Here, the new results of experimental investigations and computer simulations of wide-aperture, intense electron beam focusing by plasma lens with positive space charge cloud produced due to the cylindrical anode layer accelerator creating a positive ion stream towards an axis system is presented.

The Voyager Cosmic Ray Experiment

NASA Technical Reports Server (NTRS)

Stilwell, D. E.; Davis, W. D.; Joyce, R. M.; Mcdonald, F. B.; Trainor, J. H.; Althouse, W. E.; Cummings, A. C.; Garrard, T. L.; Stone, E. C.; Vogt, R. E.

1979-01-01

The Voyager Cosmic Ray Experiment includes seven dE/dx-E telescopes to measure the energy and charge of particles with atomic numbers from 1 to 26 in the energy range 1-500 MeV/nucleon and to measure electron energy in the range from 3 to 110 MeV. Isotopic composition of hydrogen through sulfur in the range up to 75 Mev/nucleon can also be resolved. The electronic systems include a dual-gain, charge sensitive preamplifier, 4096-channel pulse height analyzers for three parameter analysis of selected events, and an event type readout polling scheme to maximize the use of available telemetry space and to enhance the occurrence of rare events in the data. Details of the detector, electronic and mechanical design are presented.

Non-linear effects in bunch compressor of TARLA

NASA Astrophysics Data System (ADS)

Yildiz, Hüseyin; Aksoy, Avni; Arikan, Pervin

2016-03-01

Transport of a beam through an accelerator beamline is affected by high order and non-linear effects such as space charge, coherent synchrotron radiation, wakefield, etc. These effects damage form of the beam, and they lead particle loss, emittance growth, bunch length variation, beam halo formation, etc. One of the known non-linear effects on low energy machine is space charge effect. In this study we focus on space charge effect for Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) machine which is designed to drive InfraRed Free Electron Laser covering the range of 3-250 µm. Moreover, we discuss second order effects on bunch compressor of TARLA.

Dispersive electron transport in tris(8-hydroxyquinoline) aluminum (Alq3) probed by impedance spectroscopy.

PubMed

Berleb, Stefan; Brütting, Wolfgang

2002-12-31

Electron transport in tris(8-hydroxyquinoline) aluminum (Alq3) is investigated by impedance spectroscopy under conditions of space-charge limited conduction (SCLC). Existing SCLC models are extended to include the field dependence of the charge carrier mobility and energetically distributed trap states. The dispersive nature of electron transport is revealed by a frequency-dependent mobility with a dispersion parameter alpha in the range 0.4-0.5, independent of temperature. This indicates that positional rather than energetic disorder is the dominant mechanism for the dispersive transport of electrons in Alq3.

Visualization of electronic density

DOE PAGES

Grosso, Bastien; Cooper, Valentino R.; Pine, Polina; ...

2015-04-22

An atom’s volume depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent numerical algorithms and packages to calculate it for other materials. 3D visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. We explore several approaches to 3D charge density visualization, including the extension of an anaglyphic stereo visualization application based on the AViz package to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answering interesting questions about nanotube properties.

Micro faraday-element array detector for ion mobility spectroscopy

DOEpatents

Gresham, Christopher A [Albuquerque, NM; Rodacy, Phillip J [Albuquerque, NM; Denton, M Bonner [Tucson, AZ; Sperline, Roger [Tucson, AZ

2004-10-26

An ion mobility spectrometer includes a drift tube having a collecting surface covering a collecting area at one end of the tube. The surface comprises a plurality of closely spaced conductive elements on a non-conductive substrate, each conductive element being electrically insulated from each other element. A plurality of capacitive transimpedance amplifiers (CTIA) adjacent the collecting surface are electrically connected to the plurality of elements, so charge from an ion striking an element is transferred to the capacitor of the connected CTIA. A controller counts the charge on the capacitors over a period of time.

Individually addressable cathodes with integrated focusing stack or detectors

DOEpatents

Thomas, Clarence E.; Baylor, Larry R.; Voelkl, Edgar; Simpson, Michael L.; Paulus, Michael J.; Lowndes, Douglas; Whealton, John; Whitson, John C.; Wilgen, John B.

2005-07-12

Systems and method are described for addressable field emission array (AFEA) chips. A plurality of individually addressable cathodes are integrated with an electrostatic focusing stack and/or a plurality of detectors on the addressable field emission array. The systems and methods provide advantages including the avoidance of space-charge blow-up.

EOS--AM1 Nickel Hydrogen Cell Interim Life Test Report

NASA Technical Reports Server (NTRS)

Bennett, C. W.; Keys, D. J.; Rao, G. M.; Wannemacher, H. E.; Vaidyanathan H.

1999-01-01

This paper reports the interim results of the Earth Observing System AM-1 project (EOS-AM-1) nickel hydrogen cell life test being conducted under contract to National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) at the Lockheed Martin Missiles and Space (LMMS) facility in East Windsor, NJ; and at COMSAT Labs., Clarksburg, MD. The purpose of the tests is to verify that the EOS-AM-1 cell design can meet five years of real-time Low Earth Orbit (LEO) cycling. The tests include both real-time LEO and accelerated stress tests. At LMMS, the first real-time LEO simulated 99 minute orbital cycle started on February 7, 1994 and the test has been running continuously since that time, with 18202 LEO cycles completed as of September 1, 1997. Each cycle consists of a 64 minute charge (VT at 1.507 volts per cell. 1.06 C/D ratio, followed by 0.6 ampere trickle charge) and a 35 minute constant power discharge at 177 watts (22.5% DOD). At COMSAT, the accelerated stress test consists of 90 minute orbital cycles at 60% DOD with a 30 minute discharge at 60 amperes and a 60 minute charge at 40 amperes (VT at 1.54 volts per cell to 1.09 C/D ratio, followed by 0.6 ampere trickle charge). The real-time LEO life test battery consists of seven, 50AH (nameplate rating) Eagle-Picher, Inc. (EPI) Mantech cells manufactured into three. 3-cell pack assemblies (there are two place holder cells that are not part of the life test electrical circuit). The test pack is configured to simulate the conductive thermal design of the spacecraft battery, including: conductive aluminum sleeves, 3-cell pack aluminum baseplate, and honeycomb panel all mounted to a liquid (-5 C) cold plate. The entire assembly is located in a thermal chamber operatina at +30 C. The accelerated stress test unit consists of five cells mounted in machined aluminum test sleeves and is operating at +10 C. The real-time LEO life test battery has met all performance requirements throuch the first 18,202 cycles, including: end of chargee and discharge cell voltages and voltace -radients; end of charge and discharge cell pressures; within cell and between cell temperature gradients; discharge capacity; current and power levels; and all charge parameters. The accelerated stress test battery has completed 11,998 cycles when the test was terminated. The stress test unit met all test parameters. This paper reports battery performances as a function of cycle life for both the real time LEO and the accelerated life test regimes.

REVIEWS OF TOPICAL PROBLEMS: "Magnetized" black holes

NASA Astrophysics Data System (ADS)

Aliev, A. N.; Gal'tsov, D. V.

1989-01-01

Physical aspects of the theory of black holes in an external electromagnetic field are reviewed. The "magnetized" black hole model is currently widely discussed in astrophysics because it provides a basis for the explanation of the high energy activity of galactic cores and quasars. The particular feature of this model is that it predicts unusual "gravimagnetic" phenomena that arise as a result of a natural combination of effects in electrodynamics and gravitation, namely, the appearance of an inductive potential difference during the rotation of a black hole in a magnetic field, the drift of a black hole in an external electromagnetic field, the change in the chemical potential of the event horizon, the creation of an effective ergosphere of a black hole in a magnetic field, and so on. Questions relating to the description of electromagnetic fields in Kerr space-time are examined, including their influence on the space-time metric, the interaction between a rotating charged black hole and an external electromagnetic field, the motion of charged particles near "magnetized" black holes, including their spontaneous and stimulated emission, and the influence of magnetic fields on quantum-mechanical processes in black holes.

Charged polymers in high dimensions

NASA Technical Reports Server (NTRS)

Kantor, Yacov

1990-01-01

A Monte Carlo study of charged polymers with either homogeneously distributed frozen charges or with mobile charges has been performed in four and five space dimensions. The results are consistent with the renormalization-group predictions and contradict the predictions of Flory-type theory. Introduction of charge mobility does not modify the behavior of the polymers.

The Orbit of Water Droplets around Charged Rod

ERIC Educational Resources Information Center

Ferstl, Andrew; Burns, Andrew

2013-01-01

The motion of charges around a centrally charged object is often compared to gravitational orbits (such as satellites around planets). Recently, a video taken by astronaut Don Pettit onboard the International Space Station shows water droplets orbiting a charged knitting needle. Here we attempt to model this motion and estimate the charges on the…

Effects of charge inhomogeneities on elementary excitations in La 2-xSr xCuO₄

DOE PAGES

Park, S. R.; Hamann, A.; Pintschovius, L.; ...

2011-12-12

Purely local experimental probes of many copper oxide superconductors show that their electronic states are inhomogeneous in real space. For example, scanning tunneling spectroscopic imaging shows strong variations in real space, and according to nuclear quadrupole resonance (NQR) studies, the charge distribution in the bulk varies on the nanoscale. However, the analysis of the experimental results utilizing spatially averaged probes often ignores this fact. We have performed a detailed investigation of the doping dependence of the energy and linewidth of the zone-boundary Cu-O bond-stretching vibration in La 2-xSr xCuO₄ by inelastic neutron scattering. Both our results as well as previouslymore » reported angle-dependent momentum widths of the electronic spectral function detected by angle-resolved photoemission can be reproduced by including the same distribution of local environments extracted from the NQR analysis.« less

Quantum Space Charge Waves in a Waveguide Filled with Fermi-Dirac Plasmas Including Relativistic Wake Field and Quantum Statistical Pressure Effects

NASA Astrophysics Data System (ADS)

Hong, Woo-Pyo; Jung, Young-Dae

2018-03-01

The effects of quantum statistical degeneracy pressure on the propagation of the quantum space charge wave are investigated in a cylindrically bounded plasma waveguide filled with relativistically degenerate quantum Fermi-Dirac plasmas and the relativistic ion wake field. The results show that the domain of the degenerate parameter for the resonant beam instability significantly increases with an increase of the scaled beam velocity. It is found that the instability domain of the wave number increases with an increase of the degenerate parameter. It is also found that the growth rate for the resonant beam instability decreases with an increase of the degenerate parameter. In addition, it is shown that the lowest harmonic mode provides the maximum value of the growth rates. Moreover, it is shown that the instability domain of the wave number decreases with an increase of the beam velocity.

Lithium-Ion Technology for Aerospace Applications- Advancing Battery Management Electronics

NASA Astrophysics Data System (ADS)

Gitzendanner, R.; Jones, E.; Deory, C.; Carmen, D.

2005-05-01

Lithium-ion technology offers a unique, weight and volume saving, solution to the power storage needs of space applications. With higher energy and power densities than conventional technologies, such as Nickel-Hydrogen (Ni-H) and Nickel/Cadmium (Ni- Cd), and comparable cycle life and reliability, Lithium-ion technology is gaining interest in many space applications. As the demand for Lithium-ion batteries with high reliability and long life increases, the need for battery management electronics, including individual cell balancing and monitoring, becomes apparent. With onboard electronics, the cells are monitored individually, and are protected from over charge or over discharge by way of integral protection circuitry. State of Charge, State of Health and other useful telemetry can also be calculated by the integrated electronics and reported to the application. Lab-based, and real-life, testing and use of these battery systems has shown the advantages of an integrated electronics package.

Electromagnetic toroidal excitations in matter and free space.

PubMed

Papasimakis, N; Fedotov, V A; Savinov, V; Raybould, T A; Zheludev, N I

2016-03-01

The toroidal dipole is a localized electromagnetic excitation, distinct from the magnetic and electric dipoles. While the electric dipole can be understood as a pair of opposite charges and the magnetic dipole as a current loop, the toroidal dipole corresponds to currents flowing on the surface of a torus. Toroidal dipoles provide physically significant contributions to the basic characteristics of matter including absorption, dispersion and optical activity. Toroidal excitations also exist in free space as spatially and temporally localized electromagnetic pulses propagating at the speed of light and interacting with matter. We review recent experimental observations of resonant toroidal dipole excitations in metamaterials and the discovery of anapoles, non-radiating charge-current configurations involving toroidal dipoles. While certain fundamental and practical aspects of toroidal electrodynamics remain open for the moment, we envision that exploitation of toroidal excitations can have important implications for the fields of photonics, sensing, energy and information.

Controllable transition from positive space charge to negative space charge in an inverted cylindrical magnetron

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

Rane, R., E-mail: ramu@ipr.res.in; Ranjan, M.; Mukherjee, S.

2016-01-15

The combined effect of magnetic field (B), gas pressure (P), and the corresponding discharge voltage on the discharge properties of argon in inverted cylindrical magnetron has been investigated. In the experiment, anode is biased with continuous 10 ms sinusoidal half wave. It is observed that at a comparatively higher magnetic field (i.e., >200 gauss) and lower operating pressure (i.e., <1 × 10{sup −3} mbar), the discharge extinguishes and demands a high voltage to reignite. Discharge current increases with increase in magnetic field and starts reducing at sufficiently higher magnetic field for a particular discharge voltage due to restricted electron diffusion towards the anode.more » It is observed that B/P ratio plays an important role in sustaining the discharge and is constant for a discharge voltage. The discharge is transformed to negative space charge regime from positive space charge regime at certain B/P ratio and this ratio varies linearly with the discharge voltage. The space charge reversal is indicated by the radial profile of the floating potential and plasma potential in between two electrodes for different magnetic fields. At a particular higher magnetic field (beyond 100 gauss), the floating potential increases gradually with the radial distance from cathode, whereas it remains almost constant at lower magnetic field.« less

Analysis of the longitudinal space charge impedance of a round uniform beam inside parallel plates and rectangular chambers

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

Wang, L.; Li, Y.

2015-02-03

This paper analyzes the longitudinal space charge impedances of a round uniform beam inside a rectangular and parallel plate chambers using the image charge method. This analysis is valid for arbitrary wavelengths, and the calculations converge rapidly. The research shows that only a few of the image beams are needed to obtain a relative error less than 0.1%. The beam offset effect is also discussed in the analysis.

Capabilities of the Environmental Effects Branch at Marshall Space Flight Cente

NASA Technical Reports Server (NTRS)

Rogers, Jan; Finckenor, Miria; Nehls, Mary

2016-01-01

The Environmental Effects Branch at the Marshall Space Flight Center supports a myriad array of programs for NASA, DoD, and commercial space including human exploration, advanced space propulsion, improving life on Earth, and the study of the Sun, the Earth, and the solar system. The branch provides testing, evaluation, and qualification of materials for use on external spacecraft surfaces and in contamination-sensitive systems. Space environment capabilities include charged particle radiation, ultraviolet radiation, atomic oxygen, impact, plasma, and thermal vacuum, anchored by flight experiments and analysis of returned space hardware. These environmental components can be combined for solar wind or planetary surface environment studies or to evaluate synergistic effects. The Impact Testing Facility allows simulation of impacts ranging from sand and rain to micrometeoroids and orbital debris in order to evaluate materials and components for flight and ground-based systems. The Contamination Control Team is involved in the evaluation of environmentally-friendly replacements for HCFC-225 for use in propulsion oxygen systems, developing cleaning methods for additively manufactured hardware, and reducing risk for the Space Launch System.

Close-Spaced High Temperature Knudsen Flow.

DTIC Science & Technology

1986-07-15

work~was a study of discharge processes in Knudsen mode (collisionless), thermionic energy converters. Areas of research involve’mechanisms for reducing ...power densities. The mechanisms/we have chosen to study are: reduction of space-charge through a very close interelectrode gap (less than 10 microns...In order to operate at practical current densities, the effect of electron space charge must be reduced . This can be done through very close

EOS-AM1 Nickel Hydrogen Cell Interim Life Test Report

NASA Technical Reports Server (NTRS)

Bennett, C. W.; Keys, D. J.; Rao, G. M.; Wannemacher, H. E.; Vaidyanathan, H.

1997-01-01

This paper reports the interim results of the Earth Observing System AM-1 project (EOS-AM-1) nickel hydrogen cell life test being conducted under contract to National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) at the Lockheed Martin Missiles and Space (LMMS) facility in East Windsor, NJ; and at COMSAT Labs., Clarksburg, MD. The purpose of the tests is to verify that the EOS-AM-l cell design can meet five years of real-time Low Earth Orbit (LEO) cycling. The tests include both real-time LEO and accelerated stress tests. At LMMS, the first real-time LEO simulated 99 minute orbital cycle started on February 7, 1994 and the test has been running continuously since that time, with 13000 LEO cycles completed as of September 2, 1996. Each cycle consists of a 64 minute charge (VT at 1.507 volts per cell, 1.06 C/D ratio, followed by 0.6 ampere trickle charge) and a 35 minute constant power discharge at 177 watts (22.5% DOD). At COMSAT, the accelerated stress test consists of 90 minute orbital cycles at 60% DOD with a 30 minute discharge at 60 amperes and a 60 minute charge at 40 ampercs (VT at 1.54 volts per cell to 1.09 C/D ratio, followed by 0.6 ampere trickle charge). The real-time LEO life test battery consists of seven, 50AH (nameplate rating) Eagle-Picher, Inc. (EPI) Mantech cells manufactured into three, 3-cell pack assemblies (there are two place holder cells that are not part of the life test electrical circuit). The test pack is configured to simulate the conductive thermal design of the spacecraft battely, including: conductive aluminum sleeves, 3-cell pack aluminum baseplate, and honeycomb panel all mounted to a liquid (-5 C) cold plate. The entire assembly is located in a thermal chamber operating at +3 C. The accelerated stress test unit consists of five cells mounted in machined aluminum test sleeves and is operating at +10 C. The real-time LEO life test battery has met all performance requirements through the first 13,000 cycles, including: end of charge and discharge cell voltages and voltage gradients; end of chalge and discharge cell pressures; within cell and between cell temperature gradients; discharge capacity; current and power levels; and all chalge parameters. The accelerated stress test battely has completed over 5900 cycles as of 9/11/96. This paper reports both battery performances as a function of cycle life, with individual cell performance comparisons repolted for selected cycles in both tests.

Theory and experiments characterizing hypervelocity impact plasmas on biased spacecraft materials

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

Lee, Nicolas; Close, Sigrid; Goel, Ashish

2013-03-15

Space weather including solar activity and background plasma sets up spacecraft conditions that can magnify the threat from hypervelocity impacts. Hypervelocity impactors include both meteoroids, traveling between 11 and 72 km/s, and orbital debris, with typical impact speeds of 10 km/s. When an impactor encounters a spacecraft, its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. In order to study this phenomenon, we conducted ground-based experiments to study hypervelocity impact plasmas using amore » Van de Graaff dust accelerator. Iron projectiles ranging from 10{sup -16} g to 10{sup -11} g were fired at speeds of up to 70 km/s into a variety of target materials under a range of surface charging conditions representative of space weather effects. Impact plasmas associated with bare metal targets as well as spacecraft materials were studied. Plasma expansion models were developed to determine the composition and temperature of the impact plasma, shedding light on the plasma dynamics that can lead to spacecraft electrical anomalies. The dependence of these plasma properties on target material, impact speed, and surface charge was analyzed. Our work includes three major results. First, the initial temperature of the impact plasma is at least an order of magnitude lower than previously reported, providing conditions more favorable for sustained RF emission. Second, the composition of impact plasmas from glass targets, unlike that of impact plasmas from tungsten, has low dependence on impact speed, indicating a charge production mechanism that is significant down to orbital debris speeds. Finally, negative ion formation has a strong dependence on target material. These new results can inform the design and operation of spacecraft in order to mitigate future impact-related space weather anomalies and failures.« less

Theory and experiments characterizing hypervelocity impact plasmas on biased spacecraft materials

NASA Astrophysics Data System (ADS)

Lee, Nicolas; Close, Sigrid; Goel, Ashish; Lauben, David; Linscott, Ivan; Johnson, Theresa; Strauss, David; Bugiel, Sebastian; Mocker, Anna; Srama, Ralf

2013-03-01

Space weather including solar activity and background plasma sets up spacecraft conditions that can magnify the threat from hypervelocity impacts. Hypervelocity impactors include both meteoroids, traveling between 11 and 72 km/s, and orbital debris, with typical impact speeds of 10 km/s. When an impactor encounters a spacecraft, its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. In order to study this phenomenon, we conducted ground-based experiments to study hypervelocity impact plasmas using a Van de Graaff dust accelerator. Iron projectiles ranging from 10-16 g to 10-11 g were fired at speeds of up to 70 km/s into a variety of target materials under a range of surface charging conditions representative of space weather effects. Impact plasmas associated with bare metal targets as well as spacecraft materials were studied. Plasma expansion models were developed to determine the composition and temperature of the impact plasma, shedding light on the plasma dynamics that can lead to spacecraft electrical anomalies. The dependence of these plasma properties on target material, impact speed, and surface charge was analyzed. Our work includes three major results. First, the initial temperature of the impact plasma is at least an order of magnitude lower than previously reported, providing conditions more favorable for sustained RF emission. Second, the composition of impact plasmas from glass targets, unlike that of impact plasmas from tungsten, has low dependence on impact speed, indicating a charge production mechanism that is significant down to orbital debris speeds. Finally, negative ion formation has a strong dependence on target material. These new results can inform the design and operation of spacecraft in order to mitigate future impact-related space weather anomalies and failures.

Relativistic Collisions of Highly-Charged Ions

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

Ionescu, Dorin; Belkacem, Ali

1998-11-19

The physics of elementary atomic processes in relativistic collisions between highly-charged ions and atoms or other ions is briefly discussed, and some recent theoretical and experimental results in this field are summarized. They include excitation, capture, ionization, and electron-positron pair creation. The numerical solution of the two-center Dirac equation in momentum space is shown to be a powerful nonperturbative method for describing atomic processes in relativistic collisions involving heavy and highly-charged ions. By propagating negative-energy wave packets in time the evolution of the QED vacuum around heavy ions in relativistic motion is investigated. Recent results obtained from numerical calculations usingmore » massively parallel processing on the Cray-T3E supercomputer of the National Energy Research Scientific Computer Center (NERSC) at Berkeley National Laboratory are presented.« less

46 CFR 147A.13 - Person in charge of the vessel; before fumigation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... fumigation of the spaces that are determined to be safe for occupancy under § 147A.11(b)(1)(i). (b) If no spaces are determined to be safe for occupancy under § 147A.11 (b)(1)(i), the person in charge of the...

46 CFR 147A.13 - Person in charge of the vessel; before fumigation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... fumigation of the spaces that are determined to be safe for occupancy under § 147A.11(b)(1)(i). (b) If no spaces are determined to be safe for occupancy under § 147A.11 (b)(1)(i), the person in charge of the...

Noise of space-charge-limited current in solids is thermal.

NASA Technical Reports Server (NTRS)

Golder, J.; Nicolet, M.-A.; Shumka, A.

1973-01-01

The white noise level of space-charge-limited current (SCLC) of holes in a silicon device measured at five temperatures ranging from 113 to 300 K is shown to be proportional to the absolute temperature. This proves experimentally the thermal origin of noise for SCLC in solids.

Thermal noise in space-charge-limited hole current in silicon

NASA Technical Reports Server (NTRS)

Shumka, A.; Golder, J.; Nicolet, M.

1972-01-01

Present theories on noise in single-carrier space-charge-limited currents in solids have not been quantitatively substantiated by experimental evidence. To obtain such experimental verification, the noise in specially fabricated silicon structures is being measured and analyzed. The first results of this verification effort are reported.

McArthur completes a battery charge on the defibrillator during Expedition 12

NASA Image and Video Library

2005-12-16

ISS012-E-12570 (16 Dec. 2005) --- Astronaut William S. (Bill) McArthur Jr., Expedition 12 commander and NASA space station science officer, completes a battery charge on a cardiac defibrillator at the Human Research Facility (HRF) in the Destiny laboratory of the International Space Station.

Diagnostic resonant cavity for a charged particle accelerator

DOEpatents

Barov, Nikolai

2007-10-02

Disclosed is a diagnostic resonant cavity for determining characteristics of a charged particle beam, such as an electron beam, produced in a charged particle accelerator. The cavity is based on resonant quadrupole-mode and higher order cavities. Enhanced shunt impedance in such cavities is obtained by the incorporation of a set of four or more electrically conductive rods extending inwardly from either one or both of the end walls of the cavity, so as to form capacitive gaps near the outer radius of the beam tube. For typical diagnostic cavity applications, a five-fold increase in shunt impedance can be obtained. In alternative embodiments the cavity may include either four or more opposing pairs of rods which extend coaxially toward one another from the opposite end walls of the cavity and are spaced from one another to form capacitative gaps; or the cavity may include a single set of individual rods that extend from one end wall to a point adjacent the opposing end wall.

Neutron Electric Dipole Moment and Tensor Charges from Lattice QCD.

PubMed

Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Gupta, Rajan; Lin, Huey-Wen; Yoon, Boram

2015-11-20

We present lattice QCD results on the neutron tensor charges including, for the first time, a simultaneous extrapolation in the lattice spacing, volume, and light quark masses to the physical point in the continuum limit. We find that the "disconnected" contribution is smaller than the statistical error in the "connected" contribution. Our estimates in the modified minimal subtraction scheme at 2 GeV, including all systematics, are g_{T}^{d-u}=1.020(76), g_{T}^{d}=0.774(66), g_{T}^{u}=-0.233(28), and g_{T}^{s}=0.008(9). The flavor diagonal charges determine the size of the neutron electric dipole moment (EDM) induced by quark EDMs that are generated in many new scenarios of CP violation beyond the standard model. We use our results to derive model-independent bounds on the EDMs of light quarks and update the EDM phenomenology in split supersymmetry with gaugino mass unification, finding a stringent upper bound of d_{n}<4×10^{-28} e cm for the neutron EDM in this scenario.

Modeling corona sheath dynamics and effects

NASA Astrophysics Data System (ADS)

Carlson, B.; Lehtinen, N. G.

2016-12-01

The conductive lightning channel is only a centimeter or so in diameter, but charge deposited along such a narrow channel produces a large electric field that drives corona discharge in nearby air, carrying the charge outward several meters. The formation of this "corona sheath" affects a wide range of observable properties of lightning, including the overall charge carried by the channel, the shape, speed, and attenuation of impulsive currents, and the possibility of x-ray production. Simplified electrostatic and electrodynamic models of the formation of the sheath will be discussed, with results given including regions near the tip of a hypothetical channel. These results suggest that the sheath initially expands very rapidly, limiting the lifetime of the intense fields nearest the channel. The expansion gradually slows as the fields decrease, but under certain circumstances a large-scale streamer-like process can lead to enhancement of electric fields displaced from the tip of the channel, possibly suggesting a mechanism for space stem formation and leader stepping.

Solar cell radiation handbook

NASA Technical Reports Server (NTRS)

Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

1982-01-01

The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

KSC-97pc138

NASA Image and Video Library

1997-01-12

STS-81 Mission Commander Michael A. Baker is assisted into his launch/entry suit in the Operations and Checkout (O&C) Building. Baker is on his fourth space flight and will have responsibility for the 10-day mission, including the intricate docking and undocking maneuvers with the Russian Mir space station. He will also be in charge of two in-flight Risk Mitigation experiments and be the subject of a Human Life Sciences experiment. He and five crew members will shortly depart the O&C and head for Launch Pad 39B, where the Space Shuttle Atlantis will lift off during a 7-minute window that opens at 4:27 a.m. EST, January 12

Trap Modulated Charge Carrier Transport in Polyethylene/Graphene Nanocomposites.

PubMed

Li, Zhonglei; Du, Boxue; Han, Chenlei; Xu, Hang

2017-06-21

The role of trap characteristics in modulating charge transport properties is attracting much attentions in electrical and electronic engineering, which has an important effect on the electrical properties of dielectrics. This paper focuses on the electrical properties of Low-density Polyethylene (LDPE)/graphene nanocomposites (NCs), as well as the corresponding trap level characteristics. The dc conductivity, breakdown strength and space charge behaviors of NCs with the filler content of 0 wt%, 0.005 wt%, 0.01 wt%, 0.1 wt% and 0.5 wt% are studied, and their trap level distributions are characterized by isothermal discharge current (IDC) tests. The experimental results show that the 0.005 wt% LDPE/graphene NCs have a lower dc conductivity, a higher breakdown strength and a much smaller amount of space charge accumulation than the neat LDPE. It is indicated that the graphene addition with a filler content of 0.005 wt% introduces large quantities of deep carrier traps that reduce charge carrier mobility and result in the homocharge accumulation near the electrodes. The deep trap modulated charge carrier transport attributes to reduce the dc conductivity, suppress the injection of space charges into polymer bulks and enhance the breakdown strength, which is of great significance in improving electrical properties of polymer dielectrics.

Application of the NASCAP Spacecraft Simulation Tool to Investigate Electrodynamic Tether Current Collection in LEO

NASA Technical Reports Server (NTRS)

Adams, Mitzi; HabashKrause, Linda

2012-01-01

Recent interest in using electrodynamic tethers (EDTs) for orbital maneuvering in Low Earth Orbit (LEO) has prompted the development of the Marshall ElectroDynamic Tether Orbit Propagator (MEDTOP) model. The model is comprised of several modules which address various aspects of EDT propulsion, including calculation of state vectors using a standard orbit propagator (e.g., J2), an atmospheric drag model, realistic ionospheric and magnetic field models, space weather effects, and tether librations. The natural electromotive force (EMF) attained during a radially-aligned conductive tether results in electrons flowing down the tether and accumulating on the lower-altitude spacecraft. The energy that drives this EMF is sourced from the orbital energy of the system; thus, EDTs are often proposed as de-orbiting systems. However, when the current is reversed using satellite charged particle sources, then propulsion is possible. One of the most difficult challenges of the modeling effort is to ascertain the equivalent circuit between the spacecraft and the ionospheric plasma. The present study investigates the use of the NASA Charging Analyzer Program (NASCAP) to calculate currents to and from the tethered satellites and the ionospheric plasma. NASCAP is a sophisticated set of computational tools to model the surface charging of three-dimensional (3D) spacecraft surfaces in a time-varying space environment. The model's surface is tessellated into a collection of facets, and NASCAP calculates currents and potentials for each one. Additionally, NASCAP provides for the construction of one or more nested grids to calculate space potential and time-varying electric fields. This provides for the capability to track individual particles orbits, to model charged particle wakes, and to incorporate external charged particle sources. With this study, we have developed a model of calculating currents incident onto an electrodynamic tethered satellite system, and first results are shown here.

Designing heteropolymers to fold into unique structures via water-mediated interactions.

PubMed

Jamadagni, Sumanth N; Bosoy, Christian; Garde, Shekhar

2010-10-28

Hydrophobic homopolymers collapse into globular structures in water driven by hydrophobic interactions. Here we employ extensive molecular dynamics simulations to study the collapse of heteropolymers containing one or two pairs of oppositely charged monomers. We show that charging a pair of monomers can dramatically alter the most stable conformations from compact globular to more open hairpin-like. We systematically explore a subset of the sequence space of one- and two-charge-pair polymers, focusing on the locations of the charge pairs. Conformational stability is governed by a balance of hydrophobic interactions, hydration and interactions of charge groups, water-mediated charged-hydrophobic monomer repulsions, and other factors. As a result, placing charge pairs in the middle, away from the hairpin ends, leads to stable hairpin-like structures. Turning off the monomer-water attractions enhances hydrophobic interactions significantly leading to a collapse into compact globular structures even for two-charge-pair heteropolymers. In contrast, the addition of salt leads to open and extended structures, suggesting that solvation of charged monomer sites by salt ions dominates the salt-induced enhancement of hydrophobic interactions. We also test the ability of a predictive scheme based on the additivity of free energy of contact formation. The success of the scheme for symmetric two-charge-pair sequences and the failure for their flipped versions highlight the complexity of the heteropolymer conformation space and of the design problem. Collectively, our results underscore the ability of tuning water-mediated interactions to design stable nonglobular structures in water and present model heteropolymers for further studies in the extended thermodynamic space and in inhomogeneous environments.

Space charge effects on the current-voltage characteristics of gated field emitter arrays

NASA Astrophysics Data System (ADS)

Jensen, K. L.; Kodis, M. A.; Murphy, R. A.; Zaidman, E. G.

1997-07-01

Microfabricated field emitter arrays (FEAs) can provide the very high electron current densities required for rf amplifier applications, typically on the order of 100 A/cm2. Determining the dependence of emission current on gate voltage is important for the prediction of emitter performance for device applications. Field emitters use high applied fields to extract current, and therefore, unlike thermionic emitters, the current densities can exceed 103A/cm2 when averaged over an array. At such high current densities, space charge effects (i.e., the influence of charge between cathode and collector on emission) affect the emission process or initiate conditions which can lead to failure mechanisms for field emitters. A simple model of a field emitter will be used to calculate the one-dimensional space charge effects on the emission characteristics by examining two components: charge between the gate and anode, which leads to Child's law, and charge within the FEA unit cell, which gives rise to a field suppression effect which can exist for a single field emitter. The predictions of the analytical model are compared with recent experimental measurements designed to assess space charge effects and predict the onset of gate current. It is shown that negative convexity on a Fowler-Nordheim plot of Ianode(Vgate) data can be explained in terms of field depression at the emitter tip in addition to reflection of electrons by a virtual cathode created when the anode field is insufficient to extract all of the current; in particular, the effects present within the unit cell constitute a newly described effect.

Emittance growth due to static and radiative space charge forces in an electron bunch compressor

NASA Astrophysics Data System (ADS)

Talman, Richard; Malitsky, Nikolay; Stulle, Frank

2009-01-01

Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004)PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel , Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)NIMAER0168-900210.1016/S0168-9002(00)00729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]). All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance γx on beam width (as controlled by the lattice βx function) at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening , in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001), http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR). (ii) A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the 2004 FEL Conference, pp. 18-21, MOCOS05, available at http://www.JACoW.org], a code with similar capabilities. For this comparison an appropriately new, 50 MeV, “standard chicane” is introduced. Unlike CSRTrack (which neglects vertical forces) the present simulation shows substantial growth of vertical emittance. But “turning off” vertical forces in the UAL code (to match the CSRTrack treatment) brings the two codes into excellent agreement. (iii) Results are also obtained for 5 GeV electrons passing through a previously introduced “standard chicane” [Coherent Synchrotron Radiation, CSR Workshop, Berlin 2002, http://www.desy.de/csr] [of the sort needed for linear colliders and free electron lasers (FEL’s) currently under design or construction]. Relatively little emittance growth is predicted for typical bunch parameters at such high electron energy. Results are obtained for both round beams and ribbon beams (like those actually needed in practice). Little or no excess emittance growth is found for ribbon bunches compared to round bunches of the same charge and bunch width. The UAL string space charge formulation (like TraFic4 and CSRTrack) avoids the regularization step (subtracting the free-space space charge force) which is required (to remove divergence) in some methods. Also, by avoiding the need to calculate a retarded-time, four-dimensional field history, the computation time needed for realistic bunch evolution calculations is modest. Some theories of bunch dilution, because they ascribe emittance growth entirely to CSR, break down at low energy. In the present treatment, as well as CSR, all free-space Coulomb and magnetic space charge forces (but not image forces), and also the centrifugal space charge force (CSCF) are included. Charge-dependent beam steering due to CSCF, as observed recently by Beutner et al. [B. Beutner , in Proceedings of FEL Conference, BESSY, Berlin, Germany, 2006, MOPPH009], is also investigated.

The Design of a 100 GHz CARM (Cyclotron Auto-Resonance Maser) Oscillator Experiment

DTIC Science & Technology

1988-09-14

pulsed-power system must be considered. A model of the voltage pulse that consists of a linear voltage rise from zero to the operating voltage...to vary as the voltage to the 3/2 power in order to model space-charge limited flow from a relativistic diode.. As the current rises in the pulse, the...distribution due to a space-charge-limited, laminar flow of electrons based on a one-dimensional, planar, relativistic model . From the charge distribution

The heavy ions in space experiment

NASA Technical Reports Server (NTRS)

Adams, J. H., Jr.; Beahm, L. P.; Stiller, B.

1985-01-01

The Heavy Ions in Space (HIIS) experiment was developed and is currently in orbit onboard the long duration facility (LDEF). The HIIS will record relativistic cosmic ray nuclei heavier than magnesium and stopping nuclei down to helium. The experiment uses plastic track detectors that have a charge resolution of 0.15 charge units at krypton and 0.10 charge units, or better, for nuclei lighter than cobalt. The HIIS has a collecting power of 2 square meter steradians and it has already collected more than a year's data.

Full dyon excitation spectrum in extended Levin-Wen models

NASA Astrophysics Data System (ADS)

Hu, Yuting; Geer, Nathan; Wu, Yong-Shi

2018-05-01

In Levin-Wen (LW) models, a wide class of exactly solvable discrete models, for two-dimensional topological phases, it is relatively easy to describe only single-fluxon excitations, but not the charge and dyonic as well as many-fluxon excitations. To incorporate charged and dyonic excitations in (doubled) topological phases, an extension of the LW models is proposed in this paper. We first enlarge the Hilbert space with adding a tail on one of the edges of each trivalent vertex to describe the internal charge degrees of freedom at the vertex. Then, we study the full dyon spectrum of the extended LW models, including both quantum numbers and wave functions for dyonic quasiparticle excitations. The local operators associated with the dyonic excitations are shown to form the so-called tube algebra, whose representations (modules) form the quantum double (categoric center) of the input data (unitary fusion category). In physically relevant cases, the input data are from a finite or quantum group (with braiding R matrices), and we find that the elementary excitations (or dyon species), as well as any localized/isolated excited states, are characterized by three quantum numbers: charge, fluxon type, and twist. They provide a "complete basis" for many-body states in the enlarged Hilbert space. Concrete examples are presented and the relevance of our results to the electric-magnetic duality existing in the models is addressed.

Insulator charging limits direct current across tunneling metal-insulator-semiconductor junctions

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

Vilan, Ayelet

Molecular electronics studies how the molecular nature affects the probability of charge carriers to tunnel through the molecules. Nevertheless, transport is also critically affected by the contacts to the molecules, an aspect that is often overlooked. Specifically, the limited ability of non-metallic contacts to maintain the required charge balance across the fairly insulating molecule often have dramatic effects. This paper shows that in the case of lead/organic monolayer-silicon junctions, a charge balance is responsible for an unusual current scaling, with the junction diameter (perimeter), rather than its area. This is attributed to the balance between the 2D charging at themore » metal/insulator interface and the 3D charging of the semiconductor space-charge region. A derivative method is developed to quantify transport across tunneling metal-insulator-semiconductor junctions; this enables separating the tunneling barrier from the space-charge barrier for a given current-voltage curve, without complementary measurements. The paper provides practical tools to analyze specific molecular junctions compatible with existing silicon technology, and demonstrates the importance of contacts' physics in modeling charge transport across molecular junctions.« less

A Laboratory Study of the Charging/Discharging Mechanisms of a Dust Particle Exposed to an Electron Beam

NASA Technical Reports Server (NTRS)

Venturini, C. C.; Spann, J. F.; Comfort, R. H.

1999-01-01

The interaction of micron sized particles or "dust particles" with different space and planetary environments has become an important area of research. One particular area of interest is how dust particles interact with plasmas. Studies have shown that charged dust particles immersed in plasmas can alter plasma characteristics, while ions and electrons in plasmas can affect a particle's potential and thereby, its interaction with other particles. The basis for understanding these phenomena is the charging mechanisms of the dust particle, specifically, how the particle's charge and characteristics are affected when exposed to ions and electrons. At NASA Marshall Space Flight Center, a laboratory experiment has been developed to study the interaction of dust particles with electrons. Using a unique laboratory technique known as electrodynamic suspension, a single charged particle is suspended in a modified quadrupole trap. Once suspended, the particle is then exposed to an electron beam to study the charging/discharging mechanisms due to collisions of energetic electrons. The change in the particle's charge, approximations of the charging/discharging currents, and the charging/discharging yield are calculated.

Wireless Communications

NASA Astrophysics Data System (ADS)

1991-01-01

A technology utilization project led to the commercial adaptation of a Space Shuttle Orbiter wireless infrared voice communications system. The technology was adapted to a LAN system by Wilton Industries, one of the participants. Because the system is cable-free, installation charges are saved, and it can be used where cable is impractical. Resultant products include the IRplex 6000. Transceivers can be located anywhere and can include mobile receivers. The system provides wireless LAN coverage up to 44,000 square feet. applications include stock exchange communications, trade shows, emergency communications, etc.

Physics and biophysics experiments needed for improved risk assessment in space

NASA Astrophysics Data System (ADS)

Sihver, L.

To improve the risk assessment of radiation carcinogenesis, late degenerative tissue effects, acute syndromes, synergistic effects of radiation and microgravity or other spacecraft factors, and hereditary effects, on future LEO and interplanetary space missions, the radiobiological effects of cosmic radiation before and after shielding must be well understood. However, cosmic radiation is very complex and includes low and high LET components of many different neutral and charged particles. The understanding of the radiobiology of the heavy ions, from GCRs and SPEs, is still a subject of great concern due to the complicated dependence of their biological effects on the type of ion and energy, and its interaction with various targets both outside and within the spacecraft and the human body. In order to estimate the biological effects of cosmic radiation, accurate knowledge of the physics of the interactions of both charged and non-charged high-LET particles is necessary. Since it is practically impossible to measure all primary and secondary particles from all projectile-target-energy combinations needed for a correct risk assessment in space, accurate particle and heavy ion transport codes might be a helpful instrument to overcome those difficulties. These codes have to be carefully validated to make sure they fulfill preset accuracy criteria, e.g. to be able to predict particle fluence and energy distributions within a certain accuracy. When validating the accuracy of the transport codes, both space and ground-based accelerator experiments are needed. In this paper current and future physics and biophysics experiments needed for improved risk assessment in space will be discussed. The cyclotron HIRFL (heavy ion research facility in Lanzhou) and the new synchrotron CSR (cooling storage ring), which can be used to provide ion beams for space related experiments at the Institute of Modern Physics, Chinese Academy of Sciences (IMP-CAS), will be presented together with the physical and biomedical research performed at IMP-CAS.

Depolarization current relaxation process of insulating dielectrics after corona poling under different charging conditions

NASA Astrophysics Data System (ADS)

Zhang, J. W.; Zhou, T. C.; Wang, J. X.; Yang, X. F.; Zhu, F.; Tian, L. M.; Liu, R. T.

2017-10-01

As an insulating dielectric, polyimide is favorable for the application of optoelectronics, electrical insulation system in electric power industry, insulating, and packaging materials in space aircraft, due to its excellent thermal, mechanical and electrical insulating stability. The charge storage profile of such insulating dielectric is utmost important to its application, when it is exposed to electron irradiation, high voltage corona discharge or other treatments. These treatments could induce changes in physical and chemical properties of treated samples. To investigate the charge storage mechanism of the insulating dielectrics after high-voltage corona discharge, the relaxation processes responsible for corona charged polyimide films under different poling conditions were analyzed by the Thermally Stimulated Discharge Currents method (TSDC). In the results of thermal relaxation process, the appearance of various peaks in TSDC spectra provided a deep insight into the molecular status in the dielectric material and reflected stored space charge relaxation process in the insulating polymers after corona discharge treatments. Furthermore, the different space charge distribution status under various poling temperature and different discharge voltage level were also investigated, which could partly reflect the influence of the ambiance condition on the functional dielectrics after corona poling.

Alternative Fuels Data Center

Science.gov Websites

vehicle in a parking space where there is a PEV charging station and signage indicating that parking is for PEV charging only, unless the vehicle is connected to the charging equipment. Violations will be

Space environmental interactions with spacecraft surfaces

NASA Technical Reports Server (NTRS)

Stevens, J. N.

1979-01-01

Environmental interactions are defined as the response of spacecraft surfaces to the charged-particle environment. These interactions are divided into two broad categories: spacecraft passive, in which the environment acts on the surfaces and spacecraft active, in which the spacecraft or a system on the spacecraft causes the interaction. The principal spacecraft passive interaction of concern is the spacecraft charging phenomenon. The spacecraft active category introduces the concept of interactions with the thermal plasma environment and Earth's magnetic fields, which are important at all altitudes and must be considered the designs of proposed large space structures and space power systems. The status of the spacecraft charging investigations is reviewed along with the spacecraft active interactions.

Synergia: an accelerator modeling tool with 3-D space charge

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

Amundson, James F.; Spentzouris, P.; /Fermilab

2004-07-01

High precision modeling of space-charge effects, together with accurate treatment of single-particle dynamics, is essential for designing future accelerators as well as optimizing the performance of existing machines. We describe Synergia, a high-fidelity parallel beam dynamics simulation package with fully three dimensional space-charge capabilities and a higher order optics implementation. We describe the computational techniques, the advanced human interface, and the parallel performance obtained using large numbers of macroparticles. We also perform code benchmarks comparing to semi-analytic results and other codes. Finally, we present initial results on particle tune spread, beam halo creation, and emittance growth in the Fermilab boostermore » accelerator.« less

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

Valerio-Lizarraga, Cristhian A., E-mail: cristhian.alfonso.valerio.lizarraga@cern.ch; Departamento de Investigación en Física, Universidad de Sonora, Hermosillo; Lallement, Jean-Baptiste

The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H{sup −} beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directlymore » into the beam transport region has been used to modify the space charge compensation degree.« less

Non-linear effects in bunch compressor of TARLA

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

Yildiz, Hüseyin, E-mail: huseyinyildiz006@gmail.com, E-mail: huseyinyildiz@gazi.edu.tr; Aksoy, Avni; Arikan, Pervin

2016-03-25

Transport of a beam through an accelerator beamline is affected by high order and non-linear effects such as space charge, coherent synchrotron radiation, wakefield, etc. These effects damage form of the beam, and they lead particle loss, emittance growth, bunch length variation, beam halo formation, etc. One of the known non-linear effects on low energy machine is space charge effect. In this study we focus on space charge effect for Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) machine which is designed to drive InfraRed Free Electron Laser covering the range of 3-250 µm. Moreover, we discuss second order effects onmore » bunch compressor of TARLA.« less

The University of Maryland Electron Ring: A Model Recirculator for Intense Beam Physics Research

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

Bernal, S.; Li, H.; Cui, Y.

2004-12-07

The University of Maryland Electron Ring (UMER), designed for transport studies of space-charge dominated beams in a strong focusing lattice, is nearing completion. Low energy, high intensity electron beams provide an excellent model system for experimental studies with relevance to all areas that require high quality, intense charged-particle beams. In addition, UMER constitutes an important tool for benchmarking of computer codes. When completed, the UMER lattice will consist of 36 alternating-focusing (FODO) periods over an 11.5-m circumference. Current studies in UMER over about 2/3 of the ring include beam-envelope matching, halo formation, asymmetrical focusing, and longitudinal dynamics (beam bunch erosionmore » and wave propagation.) Near future, multi-turn operation of the ring will allow us to address important additional issues such as resonance-traversal, energy spread and others. The main diagnostics are phosphor screens and capacitive beam position monitors placed at the center of each 200 bending section. In addition, pepper-pot and slit-wire emittance meters are in operation. The range of beam currents used corresponds to space charge tune depressions from 0.2 to 0.8, which is unprecedented for a circular machine.« less

Battery charge regulator is coulometer controlled

NASA Technical Reports Server (NTRS)

Paulkovich, J.

1967-01-01

Coulometer controlled battery charge regulator controls nickel/cadmium type primary cells used in space applications. The use of the coulometer as an ampere hour measuring device permits all available current to go to the battery until full charge state is reached, at which time the charge rate is automatically reduced.

Analysis of Surface Charging for a Candidate Solar Sail Mission Using NASCAP-2K

NASA Technical Reports Server (NTRS)

Parker, Linda Neergaard; Minow, Joseph L.; Davis, V. A.; Mandell, Myron; Gardner, Barbara

2005-01-01

The characterization of the electromagnetic interaction for a solar sail in the solar wind environment and identification of viable charging mitigation strategies are critical solar sail mission design tasks. Spacecraft charging has important implications both for science applications and for lifetime and reliability issues of sail propulsion systems. To that end, surface charging calculations of a candidate 150-meter-class solar sail spacecraft for the 0.5 AU solar polar and 1.9 AU LI solar wind environments are performed. A model of the spacecraft with candidate materials having appropriate electrical properties is constructed using Object Toolkit. The spacecraft charging analysis is performed using Nascap-2k. the NASA/AFRL sponsored spacecraft charging analysis tool. Nominal and atypical solar wind environments appropriate for the 0.5 AU and 1.0 AU missions are used to establish current collection of solar wind ions and electrons. Finally, a geostationary orbit environment case is included to demonstrate a bounding example of extreme (negative) charging of a solar sail spacecraft. Results from the charging analyses demonstrate that minimal differential potentials (and resulting threat of electrostatic discharge) occur when the spacecraft is constructed entirely of conducting materials, as anticipated from standard guidelines for mitigation of spacecraft charging issues. Examples with dielectric materials exposed to the space environment exhibit differential potentials ranging from a few volts to extreme potentials in the kilovolt range.

Analysis of Surface Charging for a Candidate Solar Sail Mission Using Nascap-2k

NASA Technical Reports Server (NTRS)

Parker, Linda Neergaard; Minow, Joseph I.; Davis, Victoria; Mandell, Myron; Gardner, Barbara

2005-01-01

The characterization of the electromagnetic interaction for a solar sail in the solar wind environment and identification of viable charging mitigation strategies are critical solar sail mission design task. Spacecraft charging has important implications both for science applications and for lifetime and reliability issues of sail propulsion systems. To that end, surface charging calculations of a candidate 150-meter-class solar sail spacecraft for the 0.5 AU solar polar and 1.0 AU L1 solar wind environments are performed. A model of the spacecraft with candidate materials having appropriate electrical properties is constructed using Object Toolkit. The spacecraft charging analysis is performed using Nascap-2k, the NASA/AFRL sponsored spacecraft charging analysis tool. Nominal and atypical solar wind environments appropriate for the 0.5 AU and 1.0 AU missions are used to establish current collection of solar wind ions and electrons. Finally, a geostationary orbit environment case is included to demonstrate a bounding example of extreme (negative) charging of a solar sail spacecraft. Results from the charging analyses demonstrate that minimal differential potentials (and resulting threat of electrostatic discharge) occur when the spacecraft is constructed entirely of conducting materials, as anticipated from standard guidelines for mitigation of spacecraft charging issues. Examples with dielectric materials exposed to the space environment exhibit differential potentials ranging from a few volts to extreme potentials in the kilovolt range.

Recent charge-breeding developments with EBIS/T devices (invited).

PubMed

Schwarz, S; Lapierre, A

2016-02-01

Short breeding times, narrow charge state distributions, low background, high efficiency, and the flexible time structure of the ejected low-emittance ion pulses are among the most attractive features of electron beam ion source or trap (EBIS/T) based charge breeders. Significant progress has been made to further improve these properties: Several groups are working to increase current densities towards 10(3) or even 10(4) A/cm(2). These current densities will become necessary to deliver high charge states of heavy nuclei in a short time and/or provide sufficient space-charge capacity to handle high-current ion beams in next-generation rare-isotope beam (RIB) facilities. Efficient capture of continuous beams, attractive because of its potential of handling highest-current ion beams, has become possible with the development of high-density electron beams of >1 A. Requests for the time structure of the charge bred ion pulse range from ultra-short pulses to quasi-continuous beams. Progress is being made on both ends of this spectrum, by either dividing the extracted charge in many pulse-lets, adjusting the extraction potential for a near-uniform long pulse, or adding dedicated devices to spread the ion bunches delivered from the EBIS/T in time. Advances in EBIS/T charge state breeding are summarized, including recent results with NSCL's ReA EBIS/T charge breeder.

Recent charge-breeding developments with EBIS/T devices (invited)

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

Schwarz, S., E-mail: schwarz@nscl.msu.edu; Lapierre, A.

Short breeding times, narrow charge state distributions, low background, high efficiency, and the flexible time structure of the ejected low-emittance ion pulses are among the most attractive features of electron beam ion source or trap (EBIS/T) based charge breeders. Significant progress has been made to further improve these properties: Several groups are working to increase current densities towards 10{sup 3} or even 10{sup 4} A/cm{sup 2}. These current densities will become necessary to deliver high charge states of heavy nuclei in a short time and/or provide sufficient space-charge capacity to handle high-current ion beams in next-generation rare-isotope beam (RIB) facilities.more » Efficient capture of continuous beams, attractive because of its potential of handling highest-current ion beams, has become possible with the development of high-density electron beams of >1 A. Requests for the time structure of the charge bred ion pulse range from ultra-short pulses to quasi-continuous beams. Progress is being made on both ends of this spectrum, by either dividing the extracted charge in many pulse-lets, adjusting the extraction potential for a near-uniform long pulse, or adding dedicated devices to spread the ion bunches delivered from the EBIS/T in time. Advances in EBIS/T charge state breeding are summarized, including recent results with NSCL’s ReA EBIS/T charge breeder.« less

Real-space visualization of remnant Mott gap and magnon excitations.

PubMed

Wang, Y; Jia, C J; Moritz, B; Devereaux, T P

2014-04-18

We demonstrate the ability to visualize real-space dynamics of charge gap and magnon excitations in the Mott phase of the single-band Hubbard model and the remnants of these excitations with hole or electron doping. At short times, the character of magnetic and charge excitations is maintained even for large doping away from the Mott and antiferromagnetic phases. Doping influences both the real-space patterns and long timescales of these excitations with a clear carrier asymmetry attributable to particle-hole symmetry breaking in the underlying model. Further, a rapidly oscillating charge-density-wave-like pattern weakens, but persists as a visible demonstration of a subleading instability at half-filling which remains upon doping. The results offer an approach to analyzing the behavior of systems where momentum space is either inaccessible or poorly defined.

Analytical theory of the space-charge region of lateral p-n junctions in nanofilms

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

Gurugubelli, Vijaya Kumar, E-mail: vkgurugubelli@gmail.com; Karmalkar, Shreepad

There is growing interest in fabricating conventional semiconductor devices in a nanofilm which could be a 3D material with one reduced dimension (e.g., silicon-on-insulator (SOI) film), or single/multiple layers of a 2D material (e.g., MoS{sub 2}), or a two dimensional electron gas/two dimensional hole gas (2DEG/2DHG) layer. Lateral p-n junctions are essential parts of these devices. The space-charge region electrostatics in these nanofilm junctions is strongly affected by the surrounding field, unlike in bulk junctions. Current device physics of nanofilms lacks a simple analytical theory of this 2D electrostatics of lateral p-n junctions. We present such a theory taking intomore » account the film's thickness, permittivity, doping, interface charge, and possibly different ambient permittivities on film's either side. In analogy to the textbook theory of the 1D electrostatics of bulk p-n junctions, our theory yields simple formulas for the depletion width, the extent of space-charge tails beyond this width, and the screening length associated with the space-charge layer in nanofilm junctions; these formulas agree with numerical simulations and measurements. Our theory introduces an electrostatic thickness index to classify nanofilms into sheets, bulk and intermediate sized.« less

Spacecraft Charging Current Balance Model Applied to High Voltage Solar Array Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Pour, Maria Z. A.

2016-01-01

Spacecraft charging induced by high voltage solar arrays can result in power losses and degradation of spacecraft surfaces. In some cases, it can even present safety issues for astronauts performing extravehicular activities. An understanding of the dominant processes contributing to spacecraft charging induced by solar arrays is important to current space missions, such as the International Space Station, and to any future space missions that may employ high voltage solar arrays. A common method of analyzing the factors contributing to spacecraft charging is the current balance model. Current balance models are based on the simple idea that the spacecraft will float to a potential such that the current collecting to the surfaces equals the current lost from the surfaces. However, when solar arrays are involved, these currents are dependent on so many factors that the equation becomes quite complicated. In order for a current balance model to be applied to solar array operations, it must incorporate the time dependent nature of the charging of dielectric surfaces in the vicinity of conductors1-3. This poster will present the factors which must be considered when developing a current balance model for high voltage solar array operations and will compare results of a current balance model with data from the Floating Potential Measurement Unit4 on board the International Space Station.

Evaluation of Radiation Belt Space Weather Forecasts for Internal Charging Analyses

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Coffey, Victoria N.; Jun, Insoo; Garrett, Henry B.

2007-01-01

A variety of static electron radiation belt models, space weather prediction tools, and energetic electron datasets are used by spacecraft designers and operations support personnel as internal charging code inputs to evaluate electrostatic discharge risks in space systems due to exposure to relativistic electron environments. Evaluating the environment inputs is often accomplished by comparing whether the data set or forecast tool reliability predicts measured electron flux (or fluence over a given period) for some chosen period. While this technique is useful as a model metric, it does not provide the information necessary to evaluate whether short term deviances of the predicted flux is important in the charging evaluations. In this paper, we use a 1-D internal charging model to compute electric fields generated in insulating materials as a function of time when exposed to relativistic electrons in the Earth's magnetosphere. The resulting fields are assumed to represent the "true" electric fields and are compared with electric field values computed from relativistic electron environments derived from a variety of space environment and forecast tools. Deviances in predicted fields compared to the "true" fields which depend on insulator charging time constants will be evaluated as a potential metric for determining the importance of predicted and measured relativistic electron flux deviations over a range of time scales.

Space charge effect in the spiral inflector

NASA Astrophysics Data System (ADS)

Toprek, Dragan

2000-10-01

This paper presents the analytical and numerical theory of the space charge effects in the beam in the spiral inflector. It considers a simplified model of a "straight" cylindrical beam by using a uniform particle distribution. Numerical results represented in this paper are obtained by using a modified version of the program CASINO.

14 CFR 382.31 - May carriers impose special charges on passengers with a disability for providing services and...

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false May carriers impose special charges on... 382.31 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) SPECIAL REGULATIONS NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Nondiscrimination...

14 CFR 382.31 - May carriers impose special charges on passengers with a disability for providing services and...

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false May carriers impose special charges on... 382.31 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) SPECIAL REGULATIONS NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Nondiscrimination...

14 CFR 382.31 - May carriers impose special charges on passengers with a disability for providing services and...

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false May carriers impose special charges on... 382.31 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) SPECIAL REGULATIONS NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Nondiscrimination...

14 CFR 382.31 - May carriers impose special charges on passengers with a disability for providing services and...

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false May carriers impose special charges on... 382.31 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) SPECIAL REGULATIONS NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Nondiscrimination...

14 CFR 382.31 - May carriers impose special charges on passengers with a disability for providing services and...

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false May carriers impose special charges on... 382.31 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) SPECIAL REGULATIONS NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Nondiscrimination...

Triple points and phase diagrams in the extended phase space of charged Gauss-Bonnet black holes in AdS space

NASA Astrophysics Data System (ADS)

Wei, Shao-Wen; Liu, Yu-Xiao

2014-08-01

We study the triple points and phase diagrams in the extended phase space of the charged Gauss-Bonnet black holes in d-dimensional anti-de Sitter space, where the cosmological constant appears as a dynamical pressure of the system and its conjugate quantity is the thermodynamic volume of the black holes. Employing the equation of state T=T(v,P), we demonstrate that the information of the phase transition and behavior of the Gibbs free energy are potential encoded in the T-v (T-rh) line with fixed pressure P. We get the phase diagrams for the charged Gauss-Bonnet black holes with different values of the charge Q and dimension d. The result shows that the small/large black hole phase transitions appear for any d, which is reminiscent of the liquid/gas transition of a Van der Waals type. Moreover, the interesting thermodynamic phenomena, i.e., the triple points and the small/intermediate/large black hole phase transitions are observed for d=6 and Q ∈(0.1705,0.1946).

Qubit and fermionic Fock spaces from type II superstring black holes

NASA Astrophysics Data System (ADS)

Belhaj, A.; Bensed, M.; Benslimane, Z.; Sedra, M. B.; Segui, A.

Using Hodge diagram combinatorial data, we study qubit and fermionic Fock spaces from the point of view of type II superstring black holes based on complex compactifications. Concretely, we establish a one-to-one correspondence between qubits, fermionic spaces and extremal black holes in maximally supersymmetric supergravity obtained from type II superstring on complex toroidal and Calabi-Yau compactifications. We interpret the differential forms of the n-dimensional complex toroidal compactification as states of n-qubits encoding information on extremal black hole charges. We show that there are 2n copies of n qubit systems which can be split as 2n = 2n-1 + 2n-1. More precisely, 2n-1 copies are associated with even D-brane charges in type IIA superstring and the other 2n-1 ones correspond to odd D-brane charges in IIB superstring. This correspondence is generalized to a class of Calabi-Yau manifolds. In connection with black hole charges in type IIA superstring, an n-qubit system has been obtained from a canonical line bundle of n factors of one-dimensional projective space ℂℙ1.

Studies on space charge neutralization and emittance measurement of beam from microwave ion source.

PubMed

Misra, Anuraag; Goswami, A; Sing Babu, P; Srivastava, S; Pandit, V S

2015-11-01

A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

Studies on space charge neutralization and emittance measurement of beam from microwave ion source

NASA Astrophysics Data System (ADS)

Misra, Anuraag; Goswami, A.; Sing Babu, P.; Srivastava, S.; Pandit, V. S.

2015-11-01

A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (˜5 mA at 75 keV), it is possible to reduce the beam spot size by ˜34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

A Numerical Scheme for the Solution of the Space Charge Problem on a Multiply Connected Region

NASA Astrophysics Data System (ADS)

Budd, C. J.; Wheeler, A. A.

1991-11-01

In this paper we extend the work of Budd and Wheeler ( Proc. R. Soc. London A, 417, 389, 1988) , who described a new numerical scheme for the solution of the space charge equation on a simple connected domain, to multiply connected regions. The space charge equation, ▿ · ( Δ overlineϕ ▽ overlineϕ) = 0 , is a third-order nonlinear partial differential equation for the electric potential overlineϕ which models the electric field in the vicinity of a coronating conductor. Budd and Wheeler described a new way of analysing this equation by constructing an orthogonal coordinate system ( overlineϕ, overlineψ) and recasting the equation in terms of x, y, and ▽ overlineϕ as functions of ( overlineϕ, overlineψ). This transformation is singular on multiply connected regions and in this paper we show how this may be overcome to provide an efficient numerical scheme for the solution of the space charge equation. This scheme also provides a new method for the solution of Laplaces equation and the calculation of orthogonal meshes on multiply connected regions.

Experiment definition studies for AMPS Spacelab

NASA Technical Reports Server (NTRS)

Liemohn, H.

1975-01-01

The electrical charging of the space shuttle orbiter is discussed in relation to the AMPS Spacelab payload along with an operations research technique for the selection of AMPS Spacelab experiments. Experiments proposed for AMPS include: hydromagnetic wave experiments; bistatic sounder of AMPS wake; and an artificial meteor gun. Experiment objectives and instrument functions are given for all experiments.

14 CFR 158.13 - Use of PFC revenue.

Code of Federal Regulations, 2012 CFR

2012-01-01

... PASSENGER FACILITY CHARGES (PFC'S) General § 158.13 Use of PFC revenue. PFC revenue, including any interest... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Use of PFC revenue. 158.13 Section 158.13... costs of approved projects at any airport the public agency controls. (a) Total cost. PFC revenue may be...

14 CFR 158.13 - Use of PFC revenue.

Code of Federal Regulations, 2013 CFR

2013-01-01

... PASSENGER FACILITY CHARGES (PFC'S) General § 158.13 Use of PFC revenue. PFC revenue, including any interest... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Use of PFC revenue. 158.13 Section 158.13... costs of approved projects at any airport the public agency controls. (a) Total cost. PFC revenue may be...

14 CFR 158.13 - Use of PFC revenue.

Code of Federal Regulations, 2014 CFR

2014-01-01

... PASSENGER FACILITY CHARGES (PFC'S) General § 158.13 Use of PFC revenue. PFC revenue, including any interest... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Use of PFC revenue. 158.13 Section 158.13... costs of approved projects at any airport the public agency controls. (a) Total cost. PFC revenue may be...

Higher dimensional Taub-NUT spaces and applications

NASA Astrophysics Data System (ADS)

Stelea, Cristian Ionut

In the first part of this thesis we discuss classes of new exact NUT-charged solutions in four dimensions and higher, while in the remainder of the thesis we make a study of their properties and their possible applications. Specifically, in four dimensions we construct new families of axisymmetric vacuum solutions using a solution-generating technique based on the hidden SL(2,R) symmetry of the effective action. In particular, using the Schwarzschild solution as a seed we obtain the Zipoy-Voorhees generalisation of the Taub-NUT solution and of the Eguchi-Hanson soliton. Using the C-metric as a seed, we obtain and study the accelerating versions of all the above solutions. In higher dimensions we present new classes of NUT-charged spaces, generalising the previously known even-dimensional solutions to odd and even dimensions, as well as to spaces with multiple NUT-parameters. We also find the most general form of the odd-dimensional Eguchi-Hanson solitons. We use such solutions to investigate the thermodynamic properties of NUT-charged spaces in (A)dS backgrounds. These have been shown to yield counter-examples to some of the conjectures advanced in the still elusive dS/CFT paradigm (such as the maximal mass conjecture and Bousso's entropic N-bound). One important application of NUT-charged spaces is to construct higher dimensional generalisations of Kaluza-Klein magnetic monopoles, generalising the known 5-dimensional Kaluza-Klein soliton. Another interesting application involves a study of time-dependent higher-dimensional bubbles-of-nothing generated from NUT-charged solutions. We use them to test the AdS/CFT conjecture as well as to generate, by using stringy Hopf-dualities, new interesting time-dependent solutions in string theory. Finally, we construct and study new NUT-charged solutions in higher-dimensional Einstein-Maxwell theories, generalising the known Reissner-Nordstrom solutions.

A Spacecraft Charging Capability for SXTF.

DTIC Science & Technology

1979-01-17

surfaces can charge up. ’Iiiis differential charging of satellite surfaces can cause vacutum sparks , and dielectric breakdowns, and wi 11 effect the S...times required to reach steady charge state in the spacecraft internal dielectrics upon electron irradiation. In space , typical times (order of magni...WORDS (Continue on reverse side it necessary end Identify by block nunmber) Spacecraft charging Dielectric breakdown SGEMP Electron accelerators

Description of bipolar charge transport in polyethylene using a fluid model with a constant mobility: model prediction

NASA Astrophysics Data System (ADS)

LeRoy, S.; Segur, P.; Teyssedre, G.; Laurent, C.

2004-01-01

We present a conduction model aimed at describing bipolar transport and space charge phenomena in low density polyethylene under dc stress. In the first part we recall the basic requirements for the description of charge transport and charge storage in disordered media with emphasis on the case of polyethylene. A quick review of available conduction models is presented and our approach is compared with these models. Then, the bases of the model are described and related assumptions are discussed. Finally, results on external current, trapped and free space charge distributions, field distribution and recombination rate are presented and discussed, considering a constant dc voltage, a step-increase of the voltage, and a polarization-depolarization protocol for the applied voltage. It is shown that the model is able to describe the general features reported for external current, electroluminescence and charge distribution in polyethylene.

Is the negative glow plasma of a direct current glow discharge negatively charged?

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

Bogdanov, E. A.; Saifutdinov, A. I.; Demidov, V. I., E-mail: Vladimir.Demidov@mail.wvu.edu

A classic problem in gas discharge physics is discussed: what is the sign of charge density in the negative glow region of a glow discharge? It is shown that traditional interpretations in text-books on gas discharge physics that states a negative charge of the negative glow plasma are based on analogies with a simple one-dimensional model of discharge. Because the real glow discharges with a positive column are always two-dimensional, the transversal (radial) term in divergence with the electric field can provide a non-monotonic axial profile of charge density in the plasma, while maintaining a positive sign. The numerical calculationmore » of glow discharge is presented, showing a positive space charge in the negative glow under conditions, where a one-dimensional model of the discharge would predict a negative space charge.« less

Space Weather Influence on Relative Motion Control using the Touchless Electrostatic Tractor

NASA Astrophysics Data System (ADS)

Hogan, Erik A.; Schaub, Hanspeter

2016-09-01

With recent interest in the use of electrostatic forces for contactless tugging and attitude control of noncooperative objects for orbital servicing and active debris mitigation, the need for a method of remote charge control arises. In this paper, the use of a directed electron beam for remote charge control is considered in conjunction with the relative motion control. A tug vehicle emits an electron beam onto a deputy object, charging it negatively. At the same time, the tug is charged positively due to beam emission, resulting in an attractive electrostatic force. The relative position feedback control between the tug and the passive debris object is studied subject to the charging being created through an electron beam. Employing the nominal variations of the GEO space weather conditions across longitude slots, two electrostatic tugging strategies are considered. First, the electron beam current is adjusted throughout the orbit in order to maximize this resulting electrostatic force. This open-loop control strategy compensates for changes in the nominally expected local space weather environment in the GEO region to adjust for fluctuations in the local plasma return currents. Second, the performance impact of using a fixed electron beam current on the electrostatic tractor is studied if the same natural space weather variations are assumed. The fixed electron beam current shows a minor performance penalty (<5 %) while providing a much simpler implementation that does not require any knowledge of local space weather conditions.

Space-charge limitations in a collider

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

Fedotov, A.; Heimerle, M.

Design of several projects which envision hadron colliders operating at low energies such as NICA at JINR [1] and Electron-Nucleon Collider at FAIR [2] is under way. In Brookhaven National Laboratory (BNL), a new physics program requires operation of Relativistic Heavy Ion Collider (RHIC) with heavy ions at low energies at g=2.7-10 [3]. In a collider, maximum achievable luminosity is typically limited by beam-beam effects. For heavy ions significant luminosity degradation, driving bunch length and transverse emittance growth, comes from Intrabeam Scattering (IBS). At these low energies, IBS growth can be effectively counteracted, for example, with cooling techniques. If IBSmore » were the only limitation, one could achieve small hadron beam emittance and bunch length with the help of cooling, resulting in a dramatic luminosity increase. However, as a result of low energies, direct space-charge force from the beam itself is expected to become the dominant limitation. Also, the interplay of both beambeam and space-charge effects may impose an additional limitation on achievable maximum luminosity. Thus, understanding at what values of space-charge tune shift one can operate in the presence of beam-beam effects in a collider is of great interest for all of the above projects. Operation of RHIC for Low-Energy physics program started in 2010 which allowed us to have a look at combined impact of beam-beam and space-charge effects on beam lifetime experimentally. Here we briefly discuss expected limitation due to these effects with reference to recent RHIC experience.« less

Magnetically coupled resonance wireless charging technology principles and transfer mechanisms

NASA Astrophysics Data System (ADS)

Zhou, Jiehua; Wan, Jian; Ma, Yinping

2017-05-01

With the tenure of Electric-Vehicle rising around the world, the charging methods have been paid more and more attention, the current charging mode mainly has the charging posts and battery swapping station. The construction of the charging pile or battery swapping station not only require lots of manpower, material costs but the bare conductor is also easy to generate electric spark hidden safety problems, still occupies large space. Compared with the wired charging, wireless charging mode is flexible, unlimited space and location factors and charging for vehicle safety and quickly. It complements the traditional charging methods in adaptability and the independent charge deficiencies. So the researching the wireless charging system have an important practical significance and application value. In this paper, wireless charging system designed is divided into three parts: the primary side, secondary side and resonant coupling. The main function of the primary side is to generate high-frequency alternating current, so selecting CLASS-E amplifier inverter structure through the research on full bridge, half-bridge and power amplification circuit. Addition, the wireless charging system is susceptible to outside interference, frequency drift phenomenon. Combined with the wireless energy transmission characteristics, resonant parts adopt resonant coupling energy transmission scheme and the Series-Series coupling compensation structure. For the electric vehicle charging power and voltage requirements, the main circuit is a full bridge inverter and Boost circuit used as the secondary side.

The Situational Awareness Sensor Suite for the ISS (SASSI): A Mission Concept to Investigate ISS Charging and Wake Effects

NASA Technical Reports Server (NTRS)

Krause, L. Habash; Minow, J. I.; Coffey, V. N.; Gilchrist, Brian E.; Hoegy, W. R.

2014-01-01

The complex interaction between the International Space Station (ISS) and the surrounding plasma environment often generates unpredictable environmental situations that affect operations. Examples of affected systems include extravehicular activity (EVA) safety, solar panel efficiency, and scientific instrument integrity. Models and heuristically-derived best practices are well-suited for routine operations, but when it comes to unusual or anomalous events or situations, especially those driven by space weather, there is no substitute for real-time monitoring. Space environment data collected in real-time (or near-real time) can be used operationally for both real-time alarms and data sources in assimilative models to predict environmental conditions important for operational planning. Fixed space weather instruments mounted to the ISS can be used for monitoring the ambient space environment, but knowing whether or not (or to what extent) the ISS affects the measurements themselves requires adequate space situational awareness (SSA) local to the ISS. This paper presents a mission concept to use a suite of plasma instruments mounted at the end of the ISS robotic arm to systematically explore the interaction between the Space Station structure and its surrounding environment. The Situational Awareness Sensor Suite for the ISS (SASSI) would be deployed and operated on the ISS Express Logistics Carrier (ELC) for long-term "survey mode" observations and the Space Station Remote Manipulator System (SSRMS) for short-term "campaign mode" observations. Specific areas of investigation include: 1) ISS frame and surface charging during perturbations of the local ISS space environment, 2) calibration of the ISS Floating Point Measurement Unit (FPMU), 3) long baseline measurements of ambient ionospheric electric potential structures, 4) electromotive force-induced currents within large structures moving through a magnetized plasma, and 5) wake-induced ion waves in both electrostatic (i.e. particles) and electromagnetic modes. SASSI will advance the understanding of plasma-boundary interaction phenomena, demonstrate a suite a sensors acting in concert to provide effective SSA, and validate and/or calibrate existing ISS space environment instruments and models.

Advanced thermionic energy conversion

NASA Technical Reports Server (NTRS)

1979-01-01

Developments towards space and terrestrial applications of thermionic energy conversion are presented. Significant accomplishments for the three month period include: (1) devised a blade-type distributed lead design with many advantages compared to the stud-type distributed lead; (2) completed design of Marchuk tube test apparatus; (3) concluded, based on current understanding, that residual hydrogen should not contribute to a negative space charge barrier at the collector; (4) modified THX design program to include series-coupled designs as well as inductively-coupled designs; (5) initiated work on the heat transfer technology, THX test module, output power transfer system, heat transfer system, and conceptual plant design tasks; and (6) reached 2200 hours of operation in JPL-5 cylindrical converter envelope test.

Rapid Charged Geosynchronous Debris Perturbation Modeling of Electrodynamic Disturbances

NASA Astrophysics Data System (ADS)

Hughes, Joseph; Schaub, Hanspeter

2018-06-01

Charged space objects experience small perturbative torques and forces from their interaction with Earth's magnetic field. These small perturbations can change the orbits of lightweight, uncontrolled debris objects dramatically even over short periods. This paper investigates the effects of the isolated Lorentz force, the effects of including or neglecting this and other electromagnetic perturbations in a full propagation, and then analyzes for which objects electromagnetic effects have the most impact. It is found that electromagnetic forces have a negligible impact on their own. However, if the center of charge is not collocated with the center of mass, electromagnetic torques are produced which do impact the attitude, and thus the position by affecting the direction and magnitude of the solar radiation pressure force. The objects for which electrostatic torques have the most influence are charged above the kilovolt level, have a difference between their center of mass and center of charge, have highly attitude-dependent cross-sectional area, and are not spinning stably about an axis of maximum inertia. Fully coupled numerical simulation illustrate the impact of electromagnetic disturbances through the solar radiation pressure coupling.

Development of an EMCCD for lidar applications

NASA Astrophysics Data System (ADS)

De Monte, B.; Bell, R. T.

2017-11-01

A novel detector, incorporating e2v's L3 CCD (L3Vision™) [1] technology for use in LIDAR (Light Detection And Ranging) applications has been designed, manufactured and characterised. The most critical performance aspect was the requirement to collect charge from a 120μm square detection area for a 667ns temporal sampling window, with low crosstalk between successive samples, followed by signal readout with sub-electron effective noise. Additional requirements included low dark signal, high quantum efficiency at the 355nm laser wavelength and the ability to handle bright laser echoes, without corruption of the much fainter useful signals. The detector architecture used high speed charge binning to combine signal from each sampling window into a single charge packet. This was then passed through a multiplication register (Electron Multiplying Charge Coupled Device) operating with a typical gain of 100X to a conventional charge detection circuit. The detector achieved a typical quantum efficiency of 80% and a total noise in darkness of < 0.5 electrons rms. Development of the detector was supported by ESA (European Space Agency).

Rapid Charged Geosynchronous Debris Perturbation Modeling of Electrodynamic Disturbances

NASA Astrophysics Data System (ADS)

Hughes, Joseph; Schaub, Hanspeter

2018-04-01

Charged space objects experience small perturbative torques and forces from their interaction with Earth's magnetic field. These small perturbations can change the orbits of lightweight, uncontrolled debris objects dramatically even over short periods. This paper investigates the effects of the isolated Lorentz force, the effects of including or neglecting this and other electromagnetic perturbations in a full propagation, and then analyzes for which objects electromagnetic effects have the most impact. It is found that electromagnetic forces have a negligible impact on their own. However, if the center of charge is not collocated with the center of mass, electromagnetic torques are produced which do impact the attitude, and thus the position by affecting the direction and magnitude of the solar radiation pressure force. The objects for which electrostatic torques have the most influence are charged above the kilovolt level, have a difference between their center of mass and center of charge, have highly attitude-dependent cross-sectional area, and are not spinning stably about an axis of maximum inertia. Fully coupled numerical simulation illustrate the impact of electromagnetic disturbances through the solar radiation pressure coupling.

Instrumentation for Studies of Electron Emission and Charging From Insulators

NASA Technical Reports Server (NTRS)

Thomson, C. D.; Zavyalov, V.; Dennison, J. R.

2004-01-01

Making measurements of electron emission properties of insulators is difficult since insulators can charge either negatively or positively under charge particle bombardment. In addition, high incident energies or high fluences can result in modification of a material s conductivity, bulk and surface charge profile, structural makeup through bond breaking and defect creation, and emission properties. We discuss here some of the charging difficulties associated with making insulator-yield measurements and review the methods used in previous studies of electron emission from insulators. We present work undertaken by our group to make consistent and accurate measurements of the electron/ion yield properties for numerous thin-film and thick insulator materials using innovative instrumentation and techniques. We also summarize some of the necessary instrumentation developed for this purpose including fast response, low-noise, high-sensitivity ammeters; signal isolation and interface to standard computer data acquisition apparatus using opto-isolation, sample-and-hold, and boxcar integration techniques; computer control, automation and timing using Labview software; a multiple sample carousel; a pulsed, compact, low-energy, charge neutralization electron flood gun; and pulsed visible and UV light neutralization sources. This work is supported through funding from the NASA Space Environments and Effects Program and the NASA Graduate Research Fellowship Program.

Characterization of heterocyclic rings through quantum chemical topology.

PubMed

Griffiths, Mark Z; Popelier, Paul L A

2013-07-22

Five-membered rings are found in a myriad of molecules important in a wide range of areas such as catalysis, nutrition, and drug and agrochemical design. Systematic insight into their largely unexplored chemical space benefits from first principle calculations presented here. This study comprehensively investigates a grand total of 764 different rings, all geometry optimized at the B3LYP/6-311+G(2d,p) level, from the perspective of Quantum Chemical Topology (QCT). For the first time, a 3D space of local topological properties was introduced, in order to characterize rings compactly. This space is called RCP space, after the so-called ring critical point. This space is analogous to BCP space, named after the bond critical point, which compactly and successfully characterizes a chemical bond. The relative positions of the rings in RCP space are determined by the nature of the ring scaffold, such as the heteroatoms within the ring or the number of π-bonds. The summed atomic QCT charges of the five ring atoms revealed five features (number and type of heteroatom, number of π-bonds, substituent and substitution site) that dictate a ring's net charge. Each feature independently contributes toward a ring's net charge. Each substituent has its own distinct and systematic effect on the ring's net charge, irrespective of the ring scaffold. Therefore, this work proves the possibility of designing a ring with specific properties by fine-tuning it through manipulation of these five features.

Charged Particle Dose Measurements by the Odyssey/MARIE Instrument in Mars Orbit and Model Calculations

NASA Technical Reports Server (NTRS)

Cleghorn, T. F.; Saganti, P. B.; Zeitlin, C.; Cucinotta, F. A.

2004-01-01

Knowledge of the space radiation environment is crucial both for human space exploration, and robotic space missions. It is likely that human explorers will return to the moon, and then go to Mars within the next thirty years. The radiation environment that they will encounter is a significant obstacle to future exploration, and must be dealt with successfully before longterm human missions outside of the magnetosphere can take place. Shielding technologies and materials must be developed to lower the dose and dose equivalent that human beings will receive on such missions. To begin this development, a fairly complete and accurate understanding of the space environment must be obtained. The major components of the space particle radiation environment that are most hazardous to humans are: galactic cosmic rays (GCR), the particles contained in solar particle events, (SPE), and secondary particles generated in material in the spacecraft itself. The intensity of the GCR varies by roughly a factor of two over the eleven-year solar cycle, inversely with the level of solar activity. These GCR particles are fully stripped nuclei, predominantly protons and helium, but also significant numbers of heavier ions, including carbon, oxygen, and iron. Since the ionization caused by nuclei passing through matter is proportional to the square of its charge (Z=10). The MARIE instrument has been described elsewhere.

Kinetic energy offsets for multicharged ions from an electron beam ion source.

PubMed

Kulkarni, D D; Ahl, C D; Shore, A M; Miller, A J; Harriss, J E; Sosolik, C E; Marler, J P

2017-08-01

Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar 4+ and Ar 8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

Interstellar Chemistry Gets More Complex With New Charged-Molecule Discovery

NASA Astrophysics Data System (ADS)

2007-07-01

Astronomers using data from the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) have found the largest negatively-charged molecule yet seen in space. The discovery of the third negatively-charged molecule, called an anion, in less than a year and the size of the latest anion will force a drastic revision of theoretical models of interstellar chemistry, the astronomers say. Molecule formation Formation Process of Large, Negatively-Charged Molecule in Interstellar Space CREDIT: Bill Saxton, NRAO/AUI/NSF Click on image for page of graphics and detailed information "This discovery continues to add to the diversity and complexity that is already seen in the chemistry of interstellar space," said Anthony J. Remijan of the National Radio Astronomy Observatory (NRAO). "It also adds to the number of paths available for making the complex organic molecules and other large molecular species that may be precursors to life in the giant clouds from which stars and planets are formed," he added. Two teams of scientists found negatively-charged octatetraynyl, a chain of eight carbon atoms and one hydrogen atom, in the envelope of gas around an old, evolved star and in a cold, dark cloud of molecular gas. In both cases, the molecule had an extra electron, giving it a negative charge. About 130 neutral and about a dozen positively-charged molecules have been discovered in space, but the first negatively-charged molecule was not discovered until late last year. The largest previously-discovered negative ion found in space has six carbon atoms and one hydrogen atom. "Until recently, many theoretical models of how chemical reactions evolve in interstellar space have largely neglected the presence of anions. This can no longer be the case, and this means that there are many more ways to build large organic molecules in cosmic environments than have been explored," said Jan M. Hollis of NASA's Goddard Space Flight Center (GSFC). Ultraviolet light from stars can knock an electron off a molecule, creating a positively-charged ion. Astronomers had thought that molecules would not be able to retain an extra electron, and thus a negative charge, in interstellar space for a significant time. "That obviously is not the case," said Mike McCarthy of the Harvard-Smithsonian Center for Astrophysics. "Anions are surprisingly abundant in these regions." Remijan and his colleagues found the octatetraynyl anions in the envelope of the evolved giant star IRC +10 216, about 550 light-years from Earth in the constellation Leo. They found radio waves emitted at specific frequencies characteristic of the charged molecule by searching archival data from the GBT, the largest fully-steerable radio telescope in the world. Another team from the Harvard-Smithsonian Center for Astrophysics (CfA) found the same characteristic emission when they observed a cold cloud of molecular gas called TMC-1 in the constellation Taurus. These observations also were done with the GBT. In both cases, preceding laboratory experiments by the CfA team showed which radio frequencies actually are emitted by the molecule, and thus told the astronomers what to look for. "It is essential that likely interstellar molecule candidates are first studied in laboratory experiments so that the radio frequencies they can emit are known in advance of an astronomical observation," said Frank Lovas of the National Institute of Standards and Technology (NIST). Both teams announced their results in the July 20 edition of the Astrophysical Journal Letters. "With three negatively-charged molecules now found in a short period of time, and in very different environments, it appears that many more probably exist. We believe that we can discover more new species using very sensitive and advanced radio telescopes such as the GBT, once they have been characterized in the laboratory," said Sandra Bruenken of the CfA. "Further detailed studies of anions, including astronomical observations, laboratory studies, and theoretical calculations, will allow us to use them to reveal new information about the physical and chemical processes going on in interstellar space," said Martin Cordiner, of Queen's University in Belfast, Northern Ireland. "The GBT continues to take a leading role in discovering, identifying and mapping the distribution of the largest molecules ever found in astronomical environments and will continue to do so for the next several decades," said Phil Jewell of NRAO. In addition to Hollis, Lovas, Cordiner and Jewell, Remijan worked with Tom Millar of Queen's University in Belfast, Northern Ireland, and Andrew Markwick-Kemper of the University of Manchester in the UK. Bruenken worked with McCarthy, Harshal Gupta, Carl Gottlieb, and Patrick Thaddeus, all of the Harvard-Smithsonian Center for Astrophysics. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Initial Efforts in Characterizing Radiation and Plasma Effects on Space Assets: Bridging the Space Environment, Engineering and User Community

NASA Astrophysics Data System (ADS)

Zheng, Y.; Ganushkina, N. Y.; Guild, T. B.; Jiggens, P.; Jun, I.; Mazur, J. E.; Meier, M. M.; Minow, J. I.; Pitchford, D. A.; O'Brien, T. P., III; Shprits, Y.; Tobiska, W. K.; Xapsos, M.; Rastaetter, L.; Jordanova, V. K.; Kellerman, A. C.; Fok, M. C. H.

2017-12-01

The Community Coordinated Modeling Center (CCMC) has been leading the community-wide model validation projects for many years. Such effort has been broadened and extended via the newly-launched International Forum for Space Weather Modeling Capabilities Assessment (https://ccmc.gsfc.nasa.gov/assessment/), Its objective is to track space weather models' progress and performance over time, which is critically needed in space weather operations. The Radiation and Plasma Effects Working Team is working on one of the many focused evaluation topics and deals with five different subtopics: Surface Charging from 10s eV to 40 keV electrons, Internal Charging due to energetic electrons from hundreds keV to several MeVs. Single Event Effects from solar energetic particles (SEPs) and galactic cosmic rays (GCRs) (several MeV to TeVs), Total Dose due to accumulation of doses from electrons (>100 KeV) and protons (> 1 MeV) in a broad energy range, and Radiation Effects from SEPs and GCRs at aviation altitudes. A unique aspect of the Radiation and Plasma Effects focus area is that it bridges the space environments, engineering and user community. This presentation will summarize the working team's progress in metrics discussion/definition and the CCMC web interface/tools to facilitate the validation efforts. As an example, tools in the areas of surface charging/internal charging will be demoed.

Quasi-integrability in deformed sine-Gordon models and infinite towers of conserved charges

NASA Astrophysics Data System (ADS)

Blas, Harold; Callisaya, Hector Flores

2018-02-01

We have studied the space-reflection symmetries of some soliton solutions of deformed sine-Gordon models in the context of the quasi-integrability concept. Considering a dual pair of anomalous Lax representations of the deformed model we compute analytically and numerically an infinite number of alternating conserved and asymptotically conserved charges through a modification of the usual techniques of integrable field theories. The charges associated to two-solitons with a definite parity under space-reflection symmetry, i.e. kink-kink (odd parity) and kink-antikink (even parity) scatterings with equal and opposite velocities, split into two infinite towers of conserved and asymptotically conserved charges. For two-solitons without definite parity under space-reflection symmetry (kink-kink and kink-antikink scatterings with unequal and opposite velocities) our numerical results show the existence of the asymptotically conserved charges only. However, we show that in the center-of-mass reference frame of the two solitons the parity symmetries and their associated set of exactly conserved charges can be restored. Moreover, the positive parity breather-like (kink-antikink bound state) solution exhibits a tower of exactly conserved charges and a subset of charges which are periodic in time. We back up our results with extensive numerical simulations which also demonstrate the existence of long lived breather-like states in these models. The time evolution has been simulated by the 4th order Runge-Kutta method supplied with non-reflecting boundary conditions.

Absence of Disorder-Driven Metal-Insulator Transitions in Simple Holographic Models

NASA Astrophysics Data System (ADS)

Grozdanov, Sašo; Lucas, Andrew; Sachdev, Subir; Schalm, Koenraad

2015-11-01

We study electrical transport in a strongly coupled strange metal in two spatial dimensions at finite temperature and charge density, holographically dual to the Einstein-Maxwell theory in an asymptotically four-dimensional anti-de Sitter space spacetime, with arbitrary spatial inhomogeneity, up to mild assumptions including emergent isotropy. In condensed matter, these are candidate models for exotic strange metals without long-lived quasiparticles. We prove that the electrical conductivity is bounded from below by a universal minimal conductance: the quantum critical conductivity of a clean, charge-neutral plasma. Beyond nonperturbatively justifying mean-field approximations to disorder, our work demonstrates the practicality of new hydrodynamic insight into holographic transport.

Electrostatic Evaluation of the Propellant Handlers Ensemble

NASA Technical Reports Server (NTRS)

Hogue, Michael D.; Calle, Carlos I.; Buhler, Charles

2006-01-01

The Self-Contained Atmospheric Protective Ensemble (SCAPE) used in propellant handling at NASA's Kennedy Space Center (KSC) has recently completed a series of tests to determine its electrostatic properties of the coverall fabric used in the Propellant Handlers Ensemble (PHE). Understanding these electrostatic properties are fundamental to ensuring safe operations when working with flammable rocket propellants such as hydrazine, methyl hydrazine, and unsymmetrical dimethyl hydrazine. These tests include surface resistivity, charge decay, triboelectric charging, and flame incendivity. In this presentation, we will discuss the results of these tests on the current PHE as well as new fabrics and materials being evaluated for the next generation of PHE.

Relativistic fluid dynamics with spin

NASA Astrophysics Data System (ADS)

Florkowski, Wojciech; Friman, Bengt; Jaiswal, Amaresh; Speranza, Enrico

2018-04-01

Using the conservation laws for charge, energy, momentum, and angular momentum, we derive hydrodynamic equations for the charge density, local temperature, and fluid velocity, as well as for the polarization tensor, starting from local equilibrium distribution functions for particles and antiparticles with spin 1/2. The resulting set of differential equations extends the standard picture of perfect-fluid hydrodynamics with a conserved entropy current in a minimal way. This framework can be used in space-time analyses of the evolution of spin and polarization in various physical systems including high-energy nuclear collisions. We demonstrate that a stationary vortex, which exhibits vorticity-spin alignment, corresponds to a special solution of the spin-hydrodynamical equations.

An electron beam ion trap and source for re-acceleration of rare-isotope ion beams at TRIUMF

NASA Astrophysics Data System (ADS)

Blessenohl, M. A.; Dobrodey, S.; Warnecke, C.; Rosner, M. K.; Graham, L.; Paul, S.; Baumann, T. M.; Hockenbery, Z.; Hubele, R.; Pfeifer, T.; Ames, F.; Dilling, J.; Crespo López-Urrutia, J. R.

2018-05-01

Electron beam driven ionization can produce highly charged ions (HCIs) in a few well-defined charge states. Ideal conditions for this are maximally focused electron beams and an extremely clean vacuum environment. A cryogenic electron beam ion trap fulfills these prerequisites and delivers very pure HCI beams. The Canadian rare isotope facility with electron beam ion source-electron beam ion sources developed at the Max-Planck-Institut für Kernphysik (MPIK) reaches already for a 5 keV electron beam and a current of 1 A with a density in excess of 5000 A/cm2 by means of a 6 T axial magnetic field. Within the trap, the beam quickly generates a dense HCI population, tightly confined by a space-charge potential of the order of 1 keV times the ionic charge state. Emitting HCI bunches of ≈107 ions at up to 100 Hz repetition rate, the device will charge-breed rare-isotope beams with the mass-over-charge ratio required for re-acceleration at the Advanced Rare IsotopE Laboratory (ARIEL) facility at TRIUMF. We present here its design and results from commissioning runs at MPIK, including X-ray diagnostics of the electron beam and charge-breeding process, as well as ion injection and HCI-extraction measurements.

Effect of electrode materials on the space charge distribution of an Al2O3 nano-modified transformer oil under impulse voltage conditions

NASA Astrophysics Data System (ADS)

Yang, Qing; Liu, Mengna; Sima, Wenxia; Jin, Yang

2017-11-01

The combined effect mechanism of electrode materials and Al2O3 nanoparticles on the insulating characteristics of transformer oil was investigated. Impulse breakdown tests of pure transformer oil and Al2O3 nano-modified transformer oil of varying concentrations with different electrode materials (brass, aluminum and stainless steel) showed that the breakdown voltage of Al2O3 nano-modified transformer oil is higher than that of pure transformer oil and there is a there is an optimum concentration for Al2O3 nanoparticles when the breakdown voltage reaches the maximum. In addition, the breakdown voltage was highest with the brass electrode, followed by that with stainless steel and then aluminum, irrespective of the concentration of nanoparticles in the transformer oil. This is explained by the charge injection patterns from different electrode materials according to the results of space charge measurements in pure and nano-modified transformer oil using the Kerr electro-optic system. The test results indicate that there are electrode-dependent differences in the charge injection patterns and quantities and then the electric field distortion, which leads to the difference breakdown strength in result. As for the nano-modified transformer oil, due to the Al2O3 nanoparticle’s ability of shielding space charges of different polarities and the charge injection patterns of different electrodes, these two factors have different effects on the electric field distribution and breakdown process of transformer oil between different electrode materials. This paper provides a feasible approach to exploring the mechanism of the effect of the electrode material and nanoparticles on the breakdown strength of liquid dielectrics and analyzing the breakdown process using the space charge distribution.

Battery charge control with temperature compensated voltage limit

NASA Technical Reports Server (NTRS)

Thierfelder, H. E.

1983-01-01

Battery charge control for orbiting spacecraft with mission durations from three to ten years, is a critical design feature that is discussed. Starting in 1974, the General Electric Space Systems Division designed, manufactured and tested battery systems for six different space programs. Three of these are geosynchronous missions, two are medium altitude missions and one is a near-earth mission. All six power subsystems contain nickel cadmium batteries which are charged using a temperature compensated voltage limit. This charging method was found to be successful in extending the life of nickel cadmium batteries in all three types of earth orbits. Test data and flight data are presented for each type of orbit.

19 CFR 118.4 - Responsibilities of a CES operator.

Code of Federal Regulations, 2011 CFR

2011-04-01

...; (j) Provide office space, parking spaces, appropriate sanitary facilities, and potable water to Customs personnel at no charge or a charge of $1 per year; and (k) Perform in accordance with any other..., 1993, as amended by T.D. 94-81, 59 FR 51495, Oct. 12, 1994; T.D. 95-77, 60 FR 50020, Sept. 27, 1995; T...

19 CFR 118.4 - Responsibilities of a CES operator.

Code of Federal Regulations, 2014 CFR

2014-04-01

...; (j) Provide office space, parking spaces, appropriate sanitary facilities, and potable water to Customs personnel at no charge or a charge of $1 per year; and (k) Perform in accordance with any other..., 1993, as amended by T.D. 94-81, 59 FR 51495, Oct. 12, 1994; T.D. 95-77, 60 FR 50020, Sept. 27, 1995; T...

19 CFR 118.4 - Responsibilities of a CES operator.

Code of Federal Regulations, 2012 CFR

2012-04-01

...; (j) Provide office space, parking spaces, appropriate sanitary facilities, and potable water to Customs personnel at no charge or a charge of $1 per year; and (k) Perform in accordance with any other..., 1993, as amended by T.D. 94-81, 59 FR 51495, Oct. 12, 1994; T.D. 95-77, 60 FR 50020, Sept. 27, 1995; T...

19 CFR 118.4 - Responsibilities of a CES operator.

Code of Federal Regulations, 2010 CFR

2010-04-01

...; (j) Provide office space, parking spaces, appropriate sanitary facilities, and potable water to Customs personnel at no charge or a charge of $1 per year; and (k) Perform in accordance with any other..., 1993, as amended by T.D. 94-81, 59 FR 51495, Oct. 12, 1994; T.D. 95-77, 60 FR 50020, Sept. 27, 1995; T...

19 CFR 118.4 - Responsibilities of a CES operator.

Code of Federal Regulations, 2013 CFR

2013-04-01

...; (j) Provide office space, parking spaces, appropriate sanitary facilities, and potable water to Customs personnel at no charge or a charge of $1 per year; and (k) Perform in accordance with any other..., 1993, as amended by T.D. 94-81, 59 FR 51495, Oct. 12, 1994; T.D. 95-77, 60 FR 50020, Sept. 27, 1995; T...

Space-charge compensation measurements in electron cyclotron resonance ion source low energy beam transport lines with a retarding field analyzer

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

Winklehner, D.; Leitner, D., E-mail: leitnerd@nscl.msu.edu; Cole, D.

2014-02-15

In this paper we describe the first systematic measurement of beam neutralization (space charge compensation) in the ECR low energy transport line with a retarding field analyzer, which can be used to measure the potential of the beam. Expected trends for the space charge compensation levels such as increase with residual gas pressure, beam current, and beam density could be observed. However, the overall levels of neutralization are consistently low (<60%). The results and the processes involved for neutralizing ion beams are discussed for conditions typical for ECR injector beam lines. The results are compared to a simple theoretical beammore » plasma model as well as simulations.« less

Energy broadening due to space-charge oscillations in high current electron beams. [SEPAC payload experiment on Spacelab 1

NASA Technical Reports Server (NTRS)

Katz, I.; Jongeward, G. A.; Parks, D. E.; Reasoner, D. L.; Purvis, C. K.

1986-01-01

During electron beam accelerator operation on Spacelab I, substantial fluxes of electrons were observed with energies greater than the initial beam energy. Numerical calculations are performed for the emission of an unneutralized, one-dimensional electron beam. These calculations show clearly that space charge oscillations, which are associated with the charge buildup on the emitter, strongly modify the beam and cause the returning beam particles to have a distribution of kinetic energies ranging from half to over twice the initial energy.

Spacecraft Charging: Hazard Causes, Hazard Effects, Hazard Controls

NASA Technical Reports Server (NTRS)

Koontz, Steve.

2018-01-01

Spacecraft flight environments are characterized both by a wide range of space plasma conditions and by ionizing radiation (IR), solar ultraviolet and X-rays, magnetic fields, micrometeoroids, orbital debris, and other environmental factors, all of which can affect spacecraft performance. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of spacecraft charging and charging effects that can be applied to solving practical spacecraft and spacesuit engineering design, verification, and operations problems, with an emphasis on spacecraft operations in low-Earth orbit, Earth's magnetosphere, and cis-Lunar space.

Satellites, scientists track storm from Sun to surface

NASA Astrophysics Data System (ADS)

Carlowicz, Michael

1997-02-01

On January 6, the Sun spat a coronal mass ejection (CME) into the solar wind and toward Earth; by January 10, a cloud of charged particles buffeted the face of the planet. It was, by several accounts, a run-of-the-mill space weather event. But the scientific work surrounding the storm was anything but run-of-the-mill. For the first time, space physicists observed and recorded a space weather event from start to finish, from solar surface to earthly impact. Researchers are calling it the first true success story of the four-year-old International Solar Terrestrial Physics program (ISTP), which includes NASA's WIND and POLAR spacecraft; the joint Solar and Heliospheric Observatory (SOHO) mission of NASA and the European Space Agency; the joint Geotail mission of NASA and Japan's Institute of Space and Aeronautical Science; and Russia's Interball satellites.

Neutralization of beam-emitting spacecraft by plasma injection

NASA Technical Reports Server (NTRS)

Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Obayashi, T.; Roberts, W. T.; Reasoner, D. L.; Taylor, W. W. L.

1987-01-01

An impulsive plasma injection has been used to study charge neutralization of the Space Shuttle Orbiter while it was emitting an electron beam into space. This investigation was performed by Space Experiments with Particle Accelerators on Spacelab-1. A plasma consisting of 10 to the 19th argon ion-electron pairs was injected into space for 1 ms while an electron beam was also being emitted into space. The electron beam energy and current were as high as 5 keV and 300 mA. While the orbiter potential was positive before the plasma injection and began to decrease during the plasma injection, it was near zero for 6 to 20 ms after the plasma injection. The recovery time to the initial level of charging varied from 10 to 100 ms. In a laboratory test in a large space chamber using the same flight hardware, the neutralization time was 8-17 ms and the recovery time was 11-20 ms. The long duration of the neutralization effect in space can be explained by a model of diffusion of the cold plasma which is produced near the Orbiter by charge exchange between the neutral argon atoms and the energetic argon ions during plasma injection.