Exploding conducting film laser pumping apparatus

DOEpatents

Ware, K.D.; Jones, C.R.

1984-04-27

The 342-nm molecular iodine and the 1.315-..mu..m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.

An experimental platform for pulsed-power driven magnetic reconnection

NASA Astrophysics Data System (ADS)

Hare, J. D.; Suttle, L. G.; Lebedev, S. V.; Loureiro, N. F.; Ciardi, A.; Chittenden, J. P.; Clayson, T.; Eardley, S. J.; Garcia, C.; Halliday, J. W. D.; Robinson, T.; Smith, R. A.; Stuart, N.; Suzuki-Vidal, F.; Tubman, E. R.

2018-05-01

We describe a versatile pulsed-power driven platform for magnetic reconnection experiments, based on the exploding wire arrays driven in parallel [Suttle et al., Phys. Rev. Lett. 116, 225001 (2016)]. This platform produces inherently magnetised plasma flows for the duration of the generator current pulse (250 ns), resulting in a long-lasting reconnection layer. The layer exists for long enough to allow the evolution of complex processes such as plasmoid formation and movement to be diagnosed by a suite of high spatial and temporal resolution laser-based diagnostics. We can access a wide range of magnetic reconnection regimes by changing the wire material or moving the electrodes inside the wire arrays. We present results with aluminium and carbon wires, in which the parameters of the inflows and the layer that forms are significantly different. By moving the electrodes inside the wire arrays, we change how strongly the inflows are driven. This enables us to study both symmetric reconnection in a range of different regimes and asymmetric reconnection.

Evaluation of electrical conductivity and equations of state of non-ideal plasma through microsecond timescale underwater electrical wire explosion

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

Sheftman, D.; Krasik, Ya. E.

2011-09-15

Experimental and simulation results of underwater electrical Cu, Al, and W wire explosions in the microsecond timescale are presented. It was shown that the electrical conductivity results for Cu and Al agree well with modified Lee-More and quantum molecular dynamic models for temperatures above 10 kK. The equation of state (EOS) values based on SESAME tables for Cu and Al were slightly modified for intermediate temperatures in order to obtain fitting between experimental and simulated exploding wire radial expansion. Also, it was shown that the electrical conductivity results and the EOS evaluation differ significantly from the results obtained in nanosecondmore » timescale experiments. Finally, it was found that underwater electrical W wire explosion is characterized by the appearance of non-uniformities along the z-axis of the wire. This phenomena adds uncertainty to the possibility of applying this type of experiments for evaluation of the electrical conductivity and EOS of W.« less

Breakdown dynamics of electrically exploding thin metal wires in vacuum

NASA Astrophysics Data System (ADS)

Sarkisov, G. S.; Caplinger, J.; Parada, F.; Sotnikov, V. I.

2016-10-01

Using a two-frame intensified charge coupled device (iCCD) imaging system with a 2 ns exposure time, we observed the dynamics of voltage breakdown and corona generation in experiments of fast ns-time exploding fine Ni and stainless-steel (SS) wires in a vacuum. These experiments show that corona generation along the wire surface is subjected to temporal-spatial inhomogeneity. For both metal wires, we observed an initial generation of a bright cathode spot before the ionization of the entire wire length. This cathode spot does not expand with time. For 25.4 μm diameter Ni and SS wire explosions with positive polarity, breakdown starts from the ground anode and propagates to the high voltage cathode with speeds approaching 3500 km/s or approximately one percent of light speed.

Power and energy of exploding wires

DOE PAGES

Valancius, Cole J.; Garasi, Christopher J.; O?Malley, Patrick D.

2017-01-01

Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a moremore » broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.« less

Power and energy of exploding wires

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

Valancius, Cole J.; Garasi, Christopher J.; O?Malley, Patrick D.

Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a moremore » broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.« less

Characterisation of the current switch mechanism in two-stage wire array Z-pinches

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

Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.

2015-11-15

In this paper, we describe the operation of a two-stage wire array z-pinch driven by the 1.4 MA, 240 ns rise-time Magpie pulsed-power device at Imperial College London. In this setup, an inverse wire array acts as a fast current switch, delivering a current pre-pulse into a cylindrical load wire array, before rapidly switching the majority of the generator current into the load after a 100–150 ns dwell time. A detailed analysis of the evolution of the load array during the pre-pulse is presented. Measurements of the load resistivity and energy deposition suggest significant bulk heating of the array mass occurs. Themore » ∼5 kA pre-pulse delivers ∼0.8 J of energy to the load, leaving it in a mixed, predominantly liquid-vapour state. The main current switch occurs as the inverse array begins to explode and plasma expands into the load region. Electrical and imaging diagnostics indicate that the main current switch may evolve in part as a plasma flow switch, driven by the expansion of a magnetic cavity and plasma bubble along the length of the load array. Analysis of implosion trajectories suggests that approximately 1 MA switches into the load in 100 ns, corresponding to a doubling of the generator dI/dt. Potential scaling of the device to higher current machines is discussed.« less

Four-dimensional (4D) tracking of high-temperature microparticles

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

Wang, Zhehui, E-mail: zwang@lanl.gov; Liu, Q.; Waganaar, W.

High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

Four-dimensional (4D) tracking of high-temperature microparticles

NASA Astrophysics Data System (ADS)

Wang, Zhehui; Liu, Q.; Waganaar, W.; Fontanese, J.; James, D.; Munsat, T.

2016-11-01

High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

NASA Marshall Impact Testing Facility Capabilities Applicable to Lunar Dust Work

NASA Technical Reports Server (NTRS)

Evans, Steven W.; Finchum, Andy; Hubbs, Whitney; Eskridge, Richard; Martin, Jim

2008-01-01

The Impact Testing Facility at Marshall Space Flight Center has several guns that would be of use in studying impact phenomena with respect to lunar dust. These include both ballistic guns, using compressed gas and powder charges, and hypervelocity guns, either light gas guns or an exploding wire gun. In addition, a plasma drag accelerator expected to reach 20 km/s for small particles is under development. Velocity determination and impact event recording are done using ultra-high-speed cameras. Simulation analysis is also available using the SPHC hydrocode.

Four-dimensional (4D) tracking of high-temperature microparticles

DOE PAGES

Wang, Zhehui; Liu, Qiuguang; Waganaar, Bill; ...

2016-07-08

High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. As a result, velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

Four-dimensional (4D) tracking of high-temperature microparticles.

PubMed

Wang, Zhehui; Liu, Q; Waganaar, W; Fontanese, J; James, D; Munsat, T

2016-11-01

High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

Characterizing detonator output using dynamic witness plates

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

Murphy, Michael John; Adrian, Ronald J

2009-01-01

A sub-microsecond, time-resolved micro-particle-image velocimetry (PIV) system is developed to investigate the output of explosive detonators. Detonator output is directed into a transparent solid that serves as a dynamic witness plate and instantaneous shock and material velocities are measured in a two-dimensional plane cutting through the shock wave as it propagates through the solid. For the case of unloaded initiators (e.g. exploding bridge wires, exploding foil initiators, etc.) the witness plate serves as a surrogate for the explosive material that would normally be detonated. The velocity-field measurements quantify the velocity of the shocked material and visualize the geometry of themore » shocked region. Furthermore, the time-evolution of the velocity-field can be measured at intervals as small as 10 ns using the PIV system. Current experimental results of unloaded exploding bridge wire output in polydimethylsiloxane (PDMS) witness plates demonstrate 20 MHz velocity-field sampling just 300 ns after initiation of the wire.« less

Diagnostics of underwater electrical wire explosion through a time- and space-resolved hard x-ray source

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

Sheftman, D.; Shafer, D.; Efimov, S.

2012-10-15

A time- and space-resolved hard x-ray source was developed as a diagnostic tool for imaging underwater exploding wires. A {approx}4 ns width pulse of hard x-rays with energies of up to 100 keV was obtained from the discharge in a vacuum diode consisting of point-shaped tungsten electrodes. To improve contrast and image quality, an external pulsed magnetic field produced by Helmholtz coils was used. High resolution x-ray images of an underwater exploding wire were obtained using a sensitive x-ray CCD detector, and were compared to optical fast framing images. Future developments and application of this diagnostic technique are discussed.

Diagnostics of underwater electrical wire explosion through a time- and space-resolved hard x-ray source.

PubMed

Sheftman, D; Shafer, D; Efimov, S; Gruzinsky, K; Gleizer, S; Krasik, Ya E

2012-10-01

A time- and space-resolved hard x-ray source was developed as a diagnostic tool for imaging underwater exploding wires. A ~4 ns width pulse of hard x-rays with energies of up to 100 keV was obtained from the discharge in a vacuum diode consisting of point-shaped tungsten electrodes. To improve contrast and image quality, an external pulsed magnetic field produced by Helmholtz coils was used. High resolution x-ray images of an underwater exploding wire were obtained using a sensitive x-ray CCD detector, and were compared to optical fast framing images. Future developments and application of this diagnostic technique are discussed.

Patterning of Thick Parylene Films by Oxygen Plasma for Application as Exploding Foil Initiator Flyer Material

DTIC Science & Technology

2009-09-01

exploding foil initiator ( EFI ) type fuzes are being explored to...Acronyms Au gold Cr chromium Cu copper EFI exploding foil initiator BOE buffered oxide etch MEMS microelectromechanical systems RIE reactive ion...Patterning of Thick Parylene Films by Oxygen Plasma for Application as Exploding Foil Initiator Flyer Material by Eugene Zakar and Michael

Examination of rapid phase change in copper wires to improve material models and understanding of burst

NASA Astrophysics Data System (ADS)

Olles, Joseph; Garasi, Christopher; Ball, J. Patrick

2017-11-01

Electrically-pulsed wires undergo multiple phase changes including a postulated metastable phase resulting in explosive wire growth. Simulations using the MHD approximation attempt to account for the governing physics, but lack the material properties (equations-of-state and electrical conductivity) to accurately predict the phase evolution of the exploding (bursting) wire. To explore the dynamics of an exploding copper wire (in water), we employ a digital micro-Schlieren streak photography technique. This imaging quantifies wire expansion and shock waves emitted from the wire during phase changes. Using differential voltage probes, a Rogowski coil, and timing fiducials, the phase change of the wire is aligned with electrical power and energy deposition. Time-correlated electrical diagnostics and imaging allow for detailed validation of MHD simulations, comparing observed phases with phase change details found in the material property descriptions. In addition to streak imaging, a long exposure image is taken to capture axial striations along the length of the wire. These images are used to compare with results from 3D MHD simulations which propose that these perturbations impact the rate of wire expansion and temporal change in phases. If successful, the experimental data will identify areas for improvement in the material property models, and modeling results will provide insight into the details of phase change in the wire with correlation to variations in the electrical signals.

Misconceptions in the Exploding Flask Demonstration Resolved through Students' Critical Thinking

ERIC Educational Resources Information Center

Spierenburg, Rick; Jacobse, Leon; de Bruin, Iris; van den Bos, Daan J.; Vis, Dominique M.; Juurlink, Ludo B. F.

2017-01-01

As it connects to a large set of important fundamental ideas in chemistry and analytical techniques discussed in high school chemistry curricula, we review the exploding flask demonstration. In this demonstration, methanol vapor is catalytically oxidized by a Pt wire catalyst in an open container. The exothermicity of reactions occurring at the…

X-ray imaging of fibers

NASA Astrophysics Data System (ADS)

Moosman, B.; Song, Y.; Weathers, L.; Wessel, F.

1996-11-01

A pulsed x-ray backlighter was developed to image exploding wires and cryogenic fibers. The x-ray pulse width is between 10-20 ns, with an output of 100-150 mJ, mostly in the Al k-shell (1.486 keV). The backlighter is located 50 cm from the 20-50 micron diameter target (typically, a copper wire). A 15 micron Al filter eliminates UV emission from the backlighter and target. It is placed 3 cm from the target with SB-5 film directly behind it. From the optical density of the film, target absorption and density can be calculated. The spatial resolution of this system is better than 40 microns. The wire is exploded using a 10 kA, 1 microsecond pulser. Analysis with simultaneous Moire imaging will also be presented. Supported by Los Alamos National Laboratories

Review of effects of dielectric coatings on electrical exploding wires and Z pinches

NASA Astrophysics Data System (ADS)

Wu, Jian; Li, Xingwen; Li, Mo; Li, Yang; Qiu, Aici

2017-10-01

As the most powerful x-ray source in the laboratories, the wire array Z pinches have been of great relevance to inertial confinement fusions, laboratory astrophysics, and other high-energy density applications. In order to produce x-ray with greater power and higher efficiency, the dynamics of wire array has been investigated extensively, and various methods have been proposed to improve the implosion quality of the wire array. This review focuses on the experimental and theoretical investigations regarding the effects of the dielectric coatings on electrical exploding wires and Z pinches. Since the early 2000, the electrical wire explosion related to the first stage of the wire array Z pinches has been studied extensively, and the results indicated that the dielectric coatings can significantly increase the joule energy deposition into a wire in the initial stage, and even the corona free explosion of tungsten wires can be achieved. Recently, there is an increasing interest in the dynamics of insulated wire array Z pinches. By applying dielectric coatings, the ablation process is suppressed, the x-ray start time is delayed, and the possibility of multi-peak radiation is decreased. This review is organized by the evolution dynamics of wire array Z pinches, and a broad introduction to relevant scientific concepts and various other applications are presented. According to the current research status, the challenges, opportunities and further developments of Z pinch loads using dielectric coatings are proposed to further promote the researches and their applications.

EBW's and EFI's: The other electric detonators

NASA Technical Reports Server (NTRS)

Varosh, Ron

1994-01-01

Exploding Bridgewire Detonators (EBW) and Exploding Foil Initiators (EFI) which were originally developed for military applications, have found numerous uses in the non-military commercial market while still retaining their military uses. While not as common as the more familiar hot wire initiators, EBW's and EFI's have definite advantages in certain applications. These advantages, and disadvantages, are discussed for typical designs.

Neuroscientists Find Learning Is Not "Hard-Wired"

ERIC Educational Resources Information Center

Sparks, Sarah D.

2012-01-01

Neuroscience exploded into the education conversation more than 20 years ago, in step with the evolution of personal computers and the rise of the Internet, and policymakers hoped medical discoveries could likewise help doctors and teachers understand the "hard wiring" of the brain. That conception of how the brain works, exacerbated by the…

Plasma Properties of an Exploding Semiconductor Igniter

NASA Astrophysics Data System (ADS)

McGuirk, J. S.; Thomas, K. A.; Shaffer, E.; Malone, A. L.; Baginski, T.; Baginski, M. E.

1997-11-01

Requirements by the automotive industry for low-cost, pyrotechnic igniters for automotive airbags have led to the development of several semiconductor devices. The properties of the plasma produced by the vaporization of an exploding semiconductor are necessary in order to minimize the electrical energy requirements. This work considers two silicon-based semiconductor devices: the semiconductor bridge (SCB) and the semiconductor junction igniter both consisting of etched silicon with vapor deposited aluminum structures. Electrical current passing through the device heats a narrow junction region to the point of vaporization creating an aluminum and silicon low-temperature plasma. This work will investigate the electrical characteristics of both devices and infer the plasma properties. Furthermore optical spectral measurements will be taken of the exploding devices to estimate the temperature and density of the plasma.

Method for detection of nuclear-plasma interactions in a 134Xe-doped exploding pusher at the National Ignition Facility

DOE PAGES

Bleuel, Daniel L.; Bernstein, Lee A.; Brand, Christopher A.; ...

2016-06-10

Angular momentum changes due to nuclear-plasma interactions on highly-excited nuclei in high energy density plasmas created at the National Ignition Facility can be measured through a change in isomer feeding following gamma emission. Here, we propose an experiment to detect these effects in 133Xe* in exploding pusher capsules.

Method for detection of nuclear-plasma interactions in a 134Xe-doped exploding pusher at the National Ignition Facility

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

Bleuel, Daniel L.; Bernstein, Lee A.; Brand, Christopher A.

Angular momentum changes due to nuclear-plasma interactions on highly-excited nuclei in high energy density plasmas created at the National Ignition Facility can be measured through a change in isomer feeding following gamma emission. Here, we propose an experiment to detect these effects in 133Xe* in exploding pusher capsules.

Impact Testing for Materials Science at NASA - MSFC

NASA Technical Reports Server (NTRS)

Sikapizye, Mitch

2010-01-01

The Impact Testing Facility (ITF) at NASA - Marshall Space Flight Center is host to different types of guns used to study the effects of high velocity impacts. The testing facility has been and continues to be utilized for all NASA missions where impact testing is essential. The Facility has also performed tests for the Department of Defense, other corporations, as well as universities across the nation. Current capabilities provided by Marshall include ballistic guns, light gas guns, exploding wire gun, and the Hydrometeor Impact Gun. A new plasma gun has also been developed which would be able to propel particles at velocities of 20km/s. This report includes some of the guns used for impact testing at NASA Marshall and their capabilities.

Laser detonator development for test-firing applications

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

Munger, A. C.; Thomas, K. A.; Kennedy, J. E.

2004-01-01

Los Alamos National Laboratory has historically fielded two types of electro-explosive detonators. The exploding-bridgewire detonator (EBW) has an exploding wire as the initiating element, a low-density transfer charge and a high-density output pellet. The slapper detonator, or exploding-foil initiator (EFI), utilizes an exploding foil to drive a flying plate element into a high-density output pellet. The last twenty years has seen various research and development activities from many laboratories and manufacturing facilities around the world to develop laser-driven analogs of these devices, but to our knowledge none of those is in general use. Los Alamos is currently committed to designmore » and manufacture a laser analog to the long-standing, generic, general-purpose SE-1 EBW detonator, which is intended to provide increased safety in large-scale test-firing operations. This paper will discuss the major design parameters of this laser detonator and present some preliminary testing results.« less

Proceedings of the Workshop on the Chemical Suppression of Rocket Afterburning and of Gun Muzzle Flash

DTIC Science & Technology

1987-03-01

We report here the first results of this gun simulator used in the study of muzzle flash. The test setup used is shown in Figure 18. Pressure ports...experiments. For the first tests , the exploding wires mentioned above ignited the gas mixture. Later, "soft" ignition by means of a single tungsten...wire, placed axially in the chamber, was also tested . The voltage pulse applied across this hot wire is shown in Figure 19. This "soft" ignition

Underwater electrical wire explosion: Shock wave from melting being overtaken by shock wave from vaporization

NASA Astrophysics Data System (ADS)

Li, Liuxia; Qian, Dun; Zou, Xiaobing; Wang, Xinxin

2018-05-01

The shock waves generated by an underwater electrical wire explosion were investigated. A microsecond time-scale pulsed current source was used to trigger the electrical explosion of copper wires with a length of 5 cm and a diameter of 200 μm. The energy-storage capacitor was charged to a relatively low energy so that the energy deposited onto the wire was not large enough to fully vaporize the whole wire. Two shock waves were recorded with a piezoelectric gauge that was located at a position of 100 mm from the exploding wire. The first and weak shock wave was confirmed to be the contribution from wire melting, while the second and stronger shock wave was the contribution from wire vaporization. The phenomenon whereby the first shock wave generated by melting being overtaken by the shock wave due to vaporization was observed.

Magnetic properties of iron nanoparticles prepared by exploding wire technique.

PubMed

Alqudami, Abdullah; Annapoorni, S; Lamba, Subhalakshmi; Kothari, P C; Kotnala, R K

2007-06-01

Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles of different sizes can be segregated by using ultrahigh centrifuge. X-ray diffraction studies confirm the presence of the cubic phase of iron. These iron nanoparticles were found to exhibit fluorescence in the visible region in contrast to the normal bulk material. The room temperature hysteresis measurements upto a field of 1.0 tesla were performed on a suspension of iron particles in the solution as well as in the powders obtained by filtration. The hysteresis loops indicate that the particles are superparamagnetic in nature. The saturation magnetizations was approximately 60 emu/gm. As these iron particles are very sensitive to oxygen a coating of non-magnetic iron oxide tends to form around the particles giving it a core-shell structure. The core particle size is estimated theoretically from the magnetization measurements. Suspensions of iron nanoparticles in water have been proposed to be used as an effective decontaminant for ground water.

Phase Structures and Magnetic Properties of Graphite Nanosheets and Ni-Graphite Nanocomposite Synthesized by Electrical Explosion of Wire in Liquid

NASA Astrophysics Data System (ADS)

Nguyen, Minh-Thuyet; Kim, Jin-Hyung; Lee, Jung-Goo; Kim, Jin-Chun

2018-03-01

The present work studied on phases and magnetic properties of graphite nanosheets and Ni-graphite nanocomposite synthesized using the electrical explosion of wire (EEW) in ethanol. X-ray diffraction and field emission scanning electron microscope were used to investigate the phases and the morphology of the nanopowders obtained. It was found that graphite nanosheets were absolutely fabricated by EEW with a thickness of 29 nm and 3 μm diameter. The as-synthesized Ni-graphite composite powders had a Ni-coating on the surfaces of graphite sheets. The hysteresis loop of the as-exploded, the hydrogen-treated composite nanopowders and the sintered samples were examined with a vibrating sample magnetometer at room temperature. The Ni-graphite composite exposed the magnetic behaviors which are attributed to Ni component. The magnetic properties of composite had the improvement from 10.2 emu/g for the as-exploded powders to 15.8 emu/g for heat-treated powders and 49.16 emu/g for sintered samples.

Plasma arc torch with coaxial wire feed

DOEpatents

Hooper, Frederick M

2002-01-01

A plasma arc welding apparatus having a coaxial wire feed. The apparatus includes a plasma arc welding torch, a wire guide disposed coaxially inside of the plasma arc welding torch, and a hollow non-consumable electrode. The coaxial wire guide feeds non-electrified filler wire through the tip of the hollow non-consumable electrode during plasma arc welding. Non-electrified filler wires as small as 0.010 inches can be used. This invention allows precision control of the positioning and feeding of the filler wire during plasma arc welding. Since the non-electrified filler wire is fed coaxially through the center of the plasma arc torch's electrode and nozzle, the wire is automatically aimed at the optimum point in the weld zone. Therefore, there is no need for additional equipment to position and feed the filler wire from the side before or during welding.

Impact of the lateral boundary conditions resolution on dynamical downscaling of precipitation in mediterranean spain

NASA Astrophysics Data System (ADS)

Amengual, A.; Romero, R.; Homar, V.; Ramis, C.; Alonso, S.

2007-08-01

Studies using transparent, polymeric witness plates consisting of polydimethlysiloxane (PDMS) have been conducted to measure the output of exploding bridge wire (EBW) detonators and exploding foil initiators (EFI). Polymeric witness plates are utilized to alleviate particle response issues that arise in gaseous flow fields containing shock waves and to allow measurements of shock-induced material velocities to be made using particle image velocimetry (PIV). Quantitative comparisons of velocity profiles across the shock waves in air and in PDMS demonstrate the improved response achieved by the dynamic witness plate method. Schlieren photographs complement the analysis through direct visualization of detonator-induced shock waves in the witness plates.

Particle response to shock waves in solids: dynamic witness plate/PIV method for detonations

NASA Astrophysics Data System (ADS)

Murphy, Michael J.; Adrian, Ronald J.

2007-08-01

Studies using transparent, polymeric witness plates consisting of polydimethlysiloxane (PDMS) have been conducted to measure the output of exploding bridge wire (EBW) detonators and exploding foil initiators (EFI). Polymeric witness plates are utilized to alleviate particle response issues that arise in gaseous flow fields containing shock waves and to allow measurements of shock-induced material velocities to be made using particle image velocimetry (PIV). Quantitative comparisons of velocity profiles across the shock waves in air and in PDMS demonstrate the improved response achieved by the dynamic witness plate method. Schlieren photographs complement the analysis through direct visualization of detonator-induced shock waves in the witness plates.

Dynamics of Exploding Plasma Within a Magnetized Plasma

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

Dimonte, G; Dipeso, G; Hewett, D

2002-02-01

This memo describes several possible laboratory experiments on the dynamics of an exploding plasma in a background magnetized plasma. These are interesting scientifically and the results are applicable to energetic explosions in the earth's ionosphere (DOE Campaign 7 at LLNL). These proposed experiments are difficult and can only be performed in the new LAPD device at UCLA. The purpose of these experiments would be to test numerical simulations, theory and reduced models for systems performance codes. The experiments are designed to investigate the affect of the background plasma on (1) the maximum diamagnetic bubble radius given by Eq. 9; andmore » (2) the Alfven wave radiation efficiency produced by the induced current J{sub A} (Eqs. 10-12) These experiments involve measuring the bubble radius using a fast gated optical imager as in Ref [1] and the Alfven wave profile and intensity as in Ref [2] for different values of the exploding plasma energy, background plasma density and temperature, and background magnetic field. These experiments extend the previously successful experiments [2] on Alfven wave coupling. We anticipate that the proposed experiments would require 1-2 weeks of time on the LAPD. We would perform PIC simulations in support of these experiments in order to validate the codes. Once validated, the PIC simulations would then be able to be extended to realistic ionospheric conditions with various size explosions and altitudes. In addition to the Alfven wave coupling, we are interested in the magnetic containment and transport of the exploding ''debris'' plasma to see if the shorting of the radial electric field in the magnetic bubble would allow the ions to propagate further. This has important implications in an ionospheric explosion because it defines the satellite damage region. In these experiments, we would field fast gated optical cameras to obtain images of the plasma expansion, which could then be correlated with magnetic probe measurements. In this regard, it would be most helpful to have a more powerful laser more than 10J in order to increase the extent of the magnetic bubble.« less

Study of Electric Explosion of Flat Micron-Thick Foils at Current Densities of (5-50)×108 A/cm2

NASA Astrophysics Data System (ADS)

Shelkovenko, T. A.; Pikuz, S. A.; Tilikin, I. N.; Mingaleev, A. R.; Atoyan, L.; Hammer, D. A.

2018-02-01

Electric explosions of flat Al, Ti, Ni, Cu, and Ta foils with thicknesses of 1-16 μm, widths of 1-8 mm, and lengths of 5-11 mm were studied experimentally on the BIN, XP, and COBRA high-current generators at currents of 40-1000 kA and current densities of (5-50) × 108 A/cm2. The images of the exploded foils were taken at different angles to the foil surface by using point projection radiography with an X-pinch hot spot as the radiation source, the spatial resolution and exposure time being 3 μm and 50 ps, respectively, as well by the laser probing method with a spatial resolution of 20 μm and an exposure time of 180 ps. In the course of foil explosion, rapidly expanding objects resembling the core and corona of an exploded wire were observed. It is shown that the core of the exploded foil has a complicated time-varying structure.

Detonator Performance Characterization using Multi-Frame Laser Schlieren Imaging

NASA Astrophysics Data System (ADS)

Clarke, Steven; Landon, Colin; Murphy, Michael; Martinez, Michael; Mason, Thomas; Thomas, Keith

2009-06-01

Multi-frame Laser Schlieren Imaging of shock waves produced by detonators in transparent witness materials can be used to evaluate detonator performance. We use inverse calculations of the 2D propagation of shock waves in the EPIC finite element model computer code to calculate a temporal-spatial-pressure profile on the surface of the detonator that is consistent with the experimental shock waves from the schlieren imaging. Examples of calculated 2D temporal-spatial-pressure profiles from a range of detonator types (EFI --exploding foil initiators, DOI -- direct optical initiation, EBW -- exploding bridge wire, hotwire), detonator HE materials (PETN, HMX, etc), and HE densities. Also pressure interaction profiles from the interaction of multiple shock waves will be shown. LA-UR-09-00909.

Study of Electric Explosion of Flat Micron-Thick Foils at Current Densities of (5-50)×10 8A/cm 2

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

Shelkovenko, T. A.; Pikuz, S. A.; Tilikin, I. N.

Electric explosions of flat Al, Тi, Ni, Cu, and Та foils with thicknesses of 1-16 μm, widths of 1-8 mm, and lengths of 5-11 mm were studied experimentally on the BIN, XP, and COBRA high-current generators at currents of 40-1000 kA and current densities of (5–50) × 10 8 A/cm 2. The images of the exploded foils were taken at different angles to the foil surface by using point projection radiography with an X-pinch hot spot as the radiation source, the spatial resolution and exposure time being 3 μm and 50 ps, respectively, as well by the laser probing methodmore » with a spatial resolution of 20 μm and an exposure time of 180 ps. In the course of foil explosion, rapidly expanding objects resembling the core and corona of an exploded wire were observed. It is shown that the core of the exploded foil has a complicated time-varying structure.« less

Study of Electric Explosion of Flat Micron-Thick Foils at Current Densities of (5-50)×10 8A/cm 2

DOE PAGES

Shelkovenko, T. A.; Pikuz, S. A.; Tilikin, I. N.; ...

2018-01-01

Electric explosions of flat Al, Тi, Ni, Cu, and Та foils with thicknesses of 1-16 μm, widths of 1-8 mm, and lengths of 5-11 mm were studied experimentally on the BIN, XP, and COBRA high-current generators at currents of 40-1000 kA and current densities of (5–50) × 10 8 A/cm 2. The images of the exploded foils were taken at different angles to the foil surface by using point projection radiography with an X-pinch hot spot as the radiation source, the spatial resolution and exposure time being 3 μm and 50 ps, respectively, as well by the laser probing methodmore » with a spatial resolution of 20 μm and an exposure time of 180 ps. In the course of foil explosion, rapidly expanding objects resembling the core and corona of an exploded wire were observed. It is shown that the core of the exploded foil has a complicated time-varying structure.« less

Characterization of Jets From Exploding Bridge Wire Detonators

DTIC Science & Technology

2005-05-01

Laboratories: Albuquerque, NM, 1992. 8. Lee, E. L; Hornig, H. C.; Kury, J. W. Adiabatic Expansion of High Explosive Detonation Products; UCRL ...Dobratz, B. M. LLNL Explosives Handbook; UCRL -5299; Lawrence Livermore Laboratory, University of California: Livermore, CA 1981. 22...ATTN AFATL DLJR D LAMBERT EGLIN AFB FL 32542-6810 2 DARPA ATTN W SNOWDEN S WAX 3701 N FAIRFAX DR ARLINGTON VA 22203-1714 2 LOS

Assessment of Proton Deflectometry for Exploding Wire Experiments

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

Beg, Farhat Nadeem

2013-09-25

This project provides the first demonstration of the application of proton deflectometry for the diagnosis of electromagnetic field topology and current-carrying regions in Z-pinch plasma experiments. Over the course of this project several milestones were achieved. High-energy proton beam generation was demonstrated on the short-pulse high-intensity Leopard laser, (10 Joules in ~350 femtoseconds, and the proton beam generation was shown to be reproducible. Next, protons were used to probe the electromagnetic field structure of short circuit loads in order to benchmark the two numerical codes, the resistive-magnetohydrodynamics (MHD) code, Gorgon, and the hybrid particle-in-cell code, LSP for the interpretation ofmore » results. Lastly, the proton deflectometry technique was used to map the magnetic field structure of pulsed-power-driven plasma loads including wires and supersonic jets formed with metallic foils. Good agreement between the modeling and experiments has been obtained. The demonstrated technique holds great promise to significantly improve the understanding of current flow and electromagnetic field topology in pulsed power driven high energy density plasmas. Proton probing with a high intensity laser was for the first time implemented in the presence of the harsh debris and x-ray producing z-pinch environment driven by a mega-ampere-scale pulsed-power machine. The intellectual merit of the program was that it investigated strongly driven MHD systems and the influence of magnetic field topology on plasma evolution in pulsed power driven plasmas. The experimental program involved intense field-matter interaction in the generation of the proton probe, as well as the generation of plasma subjected to 1 MegaGauss scale magnetic fields. The computational aspect included two well-documented codes, in combination for the first time to provide accurate interpretation of the experimental results. The broader impact included the support of 2 graduate students, one at UCSD and one at NTF, who were exposed to both the experimental physics work, the MHD and PIC modeling of the system. A first generation college undergraduate student was employed to assist in experiments and data analysis throughout the project. Data resulting from the research program were broadly disseminated by publication in scientific journals, and presentation at international and national conferences and workshops.« less

Convergence of shock waves generated by underwater electrical explosion of cylindrical wire arrays between different boundary geometries

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

Yanuka, D.; Zinowits, H. E.; Krasik, Ya. E.

The results of experiments and numerical simulations of a shock wave propagating between either conical or parabolic bounding walls are presented. The shock wave was generated by a microsecond timescale underwater electrical explosion of a cylindrical wire array supplied by a current pulse having an amplitude of ∼230 kA and a rise time of ∼1 μs. It is shown that with the same energy density deposition into the exploding wire array, the shock wave converges faster between parabolic walls, and as a result, the pressure in the vicinity of convergence is ∼2.3 times higher than in the case of conical walls. Themore » results obtained are compared to those of earlier experiments [Antonov et al., Appl. Phys. Lett. 102, 124104 (2013)] with explosions of spherical wire arrays. It is shown that at a distance of ∼400 μm from the implosion origin the pressure obtained in the current experiments is higher than for the case of spherical wire arrays.« less

Laboratory of plasma studies. Papers on high power particle beams

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

Not Available

1990-01-01

This book contains paper on Exploding metal film active anode sources experiments on the Lion extractor Ion Diode; Long conductor time plasma opening switch experiments; and Focusing studies of an applied B{sub r} extraction diode on the Lion accelerator.

Experiments and Simulations of Exploding Aluminum Wires: Validation of ALEGRA-MHD

DTIC Science & Technology

2010-09-01

ii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 ...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) September 2010 2. REPORT TYPE Final...List of Tables vi Acknowledgements vii 1 . Introduction 1 2. Experimental Setup 2 3. Computational Setup 5 3.1 Description of ALEGRA

Investigation of a High Voltage, High Frequency Power Conditioning System for Use with Flux Compression Generators

DTIC Science & Technology

2007-06-01

missouri.edu Abstract The University of Missouri-Columbia is developing a compact pulsed power system to condition the high current signal from a...flux compression generator (FCG) to the high voltage, high frequency signal required for many pulsed power applications. The system consists of a...non-magnetic core, spiral-wound transformer, series exploding wire fuse, and an oscillating mesoband source. The flux compression generator is being

Studies of an extractor geometry magnetically insulated ion diode with an exploding metal film anode plasma

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

Rondeau, G.D.

1989-01-01

Magnetically insulated diodes (MIDs) are of interest as ion sources for inertial confinement fusion. The authors examined several issues that are of concern with MIDs, including ion turn-on delay and anode plasma production, and diode impedance history and particle current scaling with the applied magnetic field and gas spacing. The LION pulsed power generator (1.5 MV, 4 {Omega}, 40 ns pulse length) was used to power an extractor geometry magnetically insulated (radical magnetic field) ion beam diode. The diode was studied with three anode configurations. In the first, with epoxy-filled-groove (epoxy) anodes, scaling of the ion and electron currents withmore » the gap and the magnetic field was examined. He found that the observed ion current is consistent with a diode model that has been successful with barrel geometry MIDs. The electron leakage current scaled proportionally to 1/Bd{sup 2}, where d is the anode-cathode gap spacing and B is the magnetic field strength. Studies of ion beam propagation in vacuum showed that space charge non-neutrality near the magnetic field coils caused the beam to expand initially. Later in the ion pulse (20 to 30 ns), the beam expansion became much less severe. The second anode configuration utilized an electron collector protruding above an epoxy anode surface. With the collector, he observed less bremsstrahlung across the active anode region. The last anode configuration studied was the exploding metal film active anode plasma source (EMFAAPS). Current from the accelerator was directed by an electron collector or a plasma opening switch through a thin aluminum film, which exploded to form the anode plasma.« less

Characteristics of a plasma flow field produced by a metal array bridge foil explosion

NASA Astrophysics Data System (ADS)

Junying, WU; Long, WANG; Yase, LI; Lijun, YANG; Manzoor, SULTAN; Lang, CHEN

2018-07-01

To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha–Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet’s center region sharply increase because of the superposition of plasma beams.

Larger sized wire arrays on 1.5 MA Z-pinch generator

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

Safronova, A. S., E-mail: alla@unr.edu; Kantsyrev, V. L., E-mail: alla@unr.edu; Weller, M. E., E-mail: alla@unr.edu

Experiments on the UNR Zebra generator with Load Current Multiplier (LCM) allow for implosions of larger sized wire array loads than at standard current of 1 MA. Advantages of larger sized planar wire array implosions include enhanced energy coupling to plasmas, better diagnostic access to observable plasma regions, and more complex geometries of the wire loads. The experiments with larger sized wire arrays were performed on 1.5 MA Zebra with LCM (the anode-cathode gap was 1 cm, which is half the gap used in the standard mode). In particular, larger sized multi-planar wire arrays had two outer wire planes frommore » mid-atomic-number wires to create a global magnetic field (gmf) and plasma flow between them. A modified central plane with a few Al wires at the edges was put in the middle between outer planes to influence gmf and to create Al plasma flow in the perpendicular direction (to the outer arrays plasma flow). Such modified plane has different number of empty slots: it was increased from 6 up to 10, hence increasing the gap inside the middle plane from 4.9 to 7.7 mm, respectively. Such load configuration allows for more independent study of the flows of L-shell mid-atomic-number plasma (between the outer planes) and K-shell Al plasma (which first fills the gap between the edge wires along the middle plane) and their radiation in space and time. We demonstrate that such configuration produces higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions and how the load geometry (size of the gap in the middle plane) influences K-shell Al radiation. In particular, K-shell Al radiation was delayed compared to L-shell mid-atomic-number radiation when the gap in the middle plane was large enough (when the number of empty slots was increased up to ten)« less

Nitrodifluoraminoterphenyl compounds and processes

DOEpatents

Lerom, M.W.; Peters, H.M.

1975-07-08

This patent relates to the nitrodifluoraminoterphenyl compounds: 3,3''-bis (difluoramino)-2,2'' 4,4', 4'',6,6',6''-octanitro-m-terphenyl (DDONT) and 3,3''-bis(difluoramino)-2,2',2''4,4',4'',6,6',6''-nonanitro-m-terphenyl (DDNONA). Procedures are described wherein diamino precursors of the indicated compounds are prepared and the final compounds are obtained by a fluorination operation. The compounds are highly energetic and suitable for use as explosives and particularly in exploding bridge wire (EBW) detonators. (auth)

Laboratory investigations of earthquake dynamics

NASA Astrophysics Data System (ADS)

Xia, Kaiwen

In this thesis this will be attempted through controlled laboratory experiments that are designed to mimic natural earthquake scenarios. The earthquake dynamic rupturing process itself is a complicated phenomenon, involving dynamic friction, wave propagation, and heat production. Because controlled experiments can produce results without assumptions needed in theoretical and numerical analysis, the experimental method is thus advantageous over theoretical and numerical methods. Our laboratory fault is composed of carefully cut photoelastic polymer plates (Homahte-100, Polycarbonate) held together by uniaxial compression. As a unique unit of the experimental design, a controlled exploding wire technique provides the triggering mechanism of laboratory earthquakes. Three important components of real earthquakes (i.e., pre-existing fault, tectonic loading, and triggering mechanism) correspond to and are simulated by frictional contact, uniaxial compression, and the exploding wire technique. Dynamic rupturing processes are visualized using the photoelastic method and are recorded via a high-speed camera. Our experimental methodology, which is full-field, in situ, and non-intrusive, has better control and diagnostic capacity compared to other existing experimental methods. Using this experimental approach, we have investigated several problems: dynamics of earthquake faulting occurring along homogeneous faults separating identical materials, earthquake faulting along inhomogeneous faults separating materials with different wave speeds, and earthquake faulting along faults with a finite low wave speed fault core. We have observed supershear ruptures, subRayleigh to supershear rupture transition, crack-like to pulse-like rupture transition, self-healing (Heaton) pulse, and rupture directionality.

Characteristics of exploding metal wires in water with three discharge types

NASA Astrophysics Data System (ADS)

Han, Ruoyu; Wu, Jiawei; Zhou, Haibin; Ding, Weidong; Qiu, Aici; Clayson, Thomas; Wang, Yanan; Ren, Hang

2017-07-01

This paper presents the characteristics of underwater electrical wire explosion (UEWE) with three discharge types, namely, Type-A, Type-B, and Type-C. Experiments were carried out with copper and tungsten wires (4 cm long and 50-300 μm in diameter) driven by a microsecond time-scale pulsed current source with 500 J stored energy. A time-integrated spectrometer and a photodiode were used to measure the optical emission of UEWE. A Polyvinylidene Fluoride probe was adopted to record the pressure waveforms. Experimental results indicate that from Type-A to Type-C, more energy deposits prior to the voltage peak and the first peak power increases drastically. This variation of energy deposition influences the optical emission and shock wave generation process. Specifically, the light intensity decreases by more than 90% and the peak of continuous spectra moves from ˜400 nm to ˜700 nm. In addition, the peak pressure of the first shock wave increases from ˜2 MPa to more than 7.5 MPa.

Coronal plasma development in wire-array z-pinches made of twisted-pairs

NASA Astrophysics Data System (ADS)

Hoyt, C. L.; Greenly, J. B.; Gourdain, P. A.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Kusse, B. R.

2009-11-01

We have investigated coronal and core plasma development in wire array z-pinches in which single fine wires are replaced by twisted-pairs (``cable'') on the 1 MA, 100 ns rise time COBRA pulsed power generator. X-ray radiography, employed to investigate dense wire core expansion, showed periodic axial nonuniformity and evidence for shock waves developing where the individual wire plasmas collide. Laser shadowgraphy images indicated that the axial instability properties of the coronal plasma are substantially modified from ordinary wire arrays. Cable mass per unit length, material and the twist wavelength were varied in order to study their effects upon the instability wavelength. Implosion uniformity and bright-spot formation, as well as magnetic topology evolution, have also been investigated using self-emission imaging, x-ray diagnostics and small B-dot probes, respectively. Results from the cable-array z-pinches will be compared with results from ordinary wire-array z-pinches. This research was supported by the SSAA program of the National Nuclear Security Administration under DOE Cooperative agreement DE-FC03-02NA00057.

X-ray Power Increase from Symmetrized Wire-Array z-Pinch Implosions on Saturn.*

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Allshouse, G. O.; Marder, B. M.; Nash, T. J.; Mock, R. C.; Douglas, M. R.; Spielman, R. B.; Seaman, J. F.; McGurn, J. S.; Jobe, D.; Gilliland, T. L.; Vargas, M.; Struve, K. W.; Stygar, W. A.; Hammer, J. H.; Degroot, J. S.; Eddleman, J. L.; Peterson, D. L.; Whitney, K. G.; Thornhill, J. W.; Pulsifer, P. E.; Apruzese, J. P.; Mosher, D.; Maron, Y.

1996-11-01

A systematic experimental study of annular aluminum wire z-pinches on the Saturn accelerator at Sandia National Laboratories shows that, for the first time, many of the measured spatial characteristics and x-ray powers can be correlated to 1D and 2D, radiation-magneto-hydrodynamic code (RMHC) simulations when large numbers of wires are used. Calculations show that the implosion begins to transition from that of individual wire plasmas to that of a continuous plasma shell when the circumferential gap between wires in the array is reduced below 1.4 +1.3/-0.7 mm. This calculated gap coincides with the measured transition of 1.4±0.4 mm between the observed regimes of slow and rapid improvement in power output with decreasing gap. In the plasma-shell regime, x-ray power has been more than tripled over that generated in the wire-plasma regime. In the full paper, measured characteristics in the plasma-shell regime are compared with 2D, 1- and 20-mm axial length simulations of the implosion using a multi-photon-group Lagrangian RMHC^1 and a three-temperature Eulerian RMHC,^2 respectively. ^1J.H. Hammer, et al., Phys. Plasmas 3, 2063 (1996). ^2D.L. Peterson, et al., Phys. Plasmas 3, 368 (1996). Work supported by U.S. DOE Contract No. DE-AC04-94AL85000.

Blast injury face: An exemplified review of management

PubMed Central

Kumar, Vijay; Singh, Arun Kumar; Kumar, Parmod; Shenoy, Yogesh Ramdas; Verma, Anoop K.; Borole, Ateesh Jayram; Prasad, Veerendra

2013-01-01

Facial injuries are extremely common due to increased incidence of vehicular and industrial trauma and warfare injuries. But isolated injury to the face due to low voltage cells exploding is rare. In blast injury, the force can cause massive soft tissue injury, along with injury to facial fractures and damage to adnexa. Facial injury is not life threatening unless associated with other injuries of the skull and airway. The major risks to airway in facial trauma are due to anatomic alteration of patient's airway through bony and soft tissue disruption and increased chances of aspiration. The past several decades have seen a rapid growth in the range of procedures available for reconstructive purposes. However, the essential preliminary management is a must and needs to be structured. The patient, a 10-year-old boy, was joining three pencil batteries in series and twisting the wire with his teeth when one battery exploded causing severe injuries to midface and mandibular region. After stabilization, the patient was taken up for surgery. A cap splint with zygomatic suspension was done for the maxilla, and wiring of residual mandibular segments with lining and skin cover provided by a deltopectoral flap was done. Reconstructive surgeries for reconstruction of the upper lip and maintenance of oral continence were planned for the future. The present case stresses the importance of educating the masses about unsafe handling of low voltage devices, management of airway, massive soft tissue injury, along with facial fractures and damage to adnexa. PMID:24163550

Variation of high-power aluminum-wire array Z-pinch dynamics with wire number, load mass, and array radius

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Mock, R. C.; Marder, B. M.; Nash, T. J.; Spielman, R. B.; Peterson, D. L.; Roderick, N. F.; Hammer, J. H.; De Groot, J. S.; Mosher, D.; Whitney, K. G.; Apruzese, J. P.

1997-05-01

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, (as measured by the radial convergence, the radiated energy, pulse width, and power), increases with wire number. Radiation magnetohydrodynamic (RMHC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below ˜1.4 mm. In this "plasma-shell regime," many of the global radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. In this regime, measured changes in the radiation pulse width with variations in load mass and array radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple radiation-scaling models.

Decomposition of poly(amide-imide) film enameled on solid copper wire using atmospheric pressure non-equilibrium plasma.

PubMed

Sugiyama, Kazuo; Suzuki, Katsunori; Kuwasima, Shusuke; Aoki, Yosuke; Yajima, Tatsuhiko

2009-01-01

The decomposition of a poly(amide-imide) thin film coated on a solid copper wire was attempted using atmospheric pressure non-equilibrium plasma. The plasma was produced by applying microwave power to an electrically conductive material in a gas mixture of argon, oxygen, and hydrogen. The poly(amide-imide) thin film was easily decomposed by argon-oxygen mixed gas plasma and an oxidized copper surface was obtained. The reduction of the oxidized surface with argon-hydrogen mixed gas plasma rapidly yielded a metallic copper surface. A continuous plasma heat-treatment process using a combination of both the argon-oxygen plasma and argon-hydrogen plasma was found to be suitable for the decomposition of the poly(amide-imide) thin film coated on the solid copper wire.

Wire array Z-pinch insights for enhanced x-ray production

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Mock, R. C.; Spielman, R. B.; Haines, M. G.; Chittenden, J. P.; Whitney, K. G.; Apruzese, J. P.; Peterson, D. L.; Greenly, J. B.; Sinars, D. B.; Reisman, D. B.; Mosher, D.

1999-05-01

Comparisons of measured total radiated x-ray power from annular wire-array z-pinches with a variety of models as a function of wire number, array mass, and load radius are reviewed. The data, which are comprehensive, have provided important insights into the features of wire-array dynamics that are critical for high x-ray power generation. Collectively, the comparisons of the data with the model calculations suggest that a number of underlying dynamical mechanisms involving cylindrical asymmetries and plasma instabilities contribute to the measured characteristics. For example, under the general assumption that the measured risetime of the total-radiated-power pulse is related to the thickness of the plasma shell formed on axis, the Heuristic Model [IEEE Trans. Plasma Sci. 26, 1275 (1998)] agrees with the measured risetime under a number of specific assumptions about the way the breakdown of the wires, the wire-plasma expansion, and the Rayleigh-Taylor instability in the r-z plane, develop. Likewise, in the high wire-number regime (where the wires are calculated to form a plasma shell prior to significant radial motion of the shell) the comparisons show that the variation in the power of the radiation generated as a function of load mass and array radius can be simulated by the two-dimensional Eulerian-radiation- magnetohydrodynamics code (E-RMHC) [Phys. Plasmas 3, 368 (1996)], using a single random-density perturbation that seeds the Rayleigh-Taylor instability in the r-z plane. For a given pulse-power generator, the comparisons suggest that (1) the smallest interwire gaps compatible with practical load construction and (2) the minimum implosion time consistent with the optimum required energy coupling of the generator to the load should produce the highest total-radiated-power levels.

Wire ablation dynamics model and its application to imploding wire arrays of different geometries.

PubMed

Esaulov, A A; Kantsyrev, V L; Safronova, A S; Velikovich, A L; Shrestha, I K; Williamson, K M; Osborne, G C

2012-10-01

The paper presents an extended description of the amplified wire ablation dynamics model (WADM), which accounts in a single simulation for the processes of wire ablation and implosion of a wire array load of arbitrary geometry and wire material composition. To investigate the role of wire ablation effects, the implosions of cylindrical and planar wire array loads at the university based generators Cobra (Cornell University) and Zebra (University of Nevada, Reno) have been analyzed. The analysis of the experimental data shows that the wire mass ablation rate can be described as a function of the current through the wire and some coefficient defined by the wire material properties. The aluminum wires were found to ablate with the highest rate, while the copper ablation is the slowest one. The lower wire ablation rate results in a higher inward velocity of the ablated plasma, a higher rate of the energy coupling with the ablated plasma, and a more significant delay of implosion for a heavy load due to the ablation effects, which manifest the most in a cylindrical array configuration and almost vanish in a single-planar array configuration. The WADM is an efficient tool suited for wire array load design and optimization in wide parameter ranges, including the loads with specific properties needed for the inertial confinement fusion research and laboratory astrophysics experiments. The data output from the WADM simulation can be used to simplify the radiation magnetohydrodynamics modeling of the wire array plasma.

Involvement of prostaglandins and histamine in nickel wire-induced acute inflammation in mice.

PubMed

Hirasawa, Noriyasu; Goi, Yoshiaki; Tanaka, Rina; Ishihara, Kenji; Ohtsu, Hiroshi; Ohuchi, Kazuo

2010-06-15

The irritancy of Nickel (Ni) ions has been well documented clinically. However, the chemical mediators involved in the acute inflammation induced by solid Ni are not fully understood. We used the Ni wire-implantation model in mice and examined roles of prostaglandins and histamine in plasma leakage in the acute phase. The subcutaneous implantation of a Ni wire into the back of mice induced plasma leakage from 8 to 24 h and tissue necrosis around the wire at 3 days, whereas the implantation of an aluminum wire induced no such inflammatory responses. An increase in the mRNA for cyclooxygenase (COX)-2 and HDC in cells around the Ni wire was detected 4 h after the implantation. The leakage of plasma at 8 h was inhibited by indomethacin in a dose-dependent manner. Dexamethasone and the p38 MAP kinase inhibitor SB203580 also inhibited the exudation of plasma consistent with the inhibition of the expression of COX-2 mRNA. Furthermore, plasma leakage was partially but siginificantly reduced in histamine H1 receptor knockout mice and histidine decarboxylase (HDC) knockout mice but not in H2 receptor knockout mice. These results suggested that the Ni ions released from the wire induced the expression of COX-2 and HDC, resulting in an increase in vascular permeability during the acute phase of inflammation. (c) 2009 Wiley Periodicals, Inc.

Mid-Atomic-Number Cylindrical Wire Array Precursor Plasma Studies on Zebra

DOE PAGES

Stafford, A; Safronova, A. S.; Kantsyrev, V. L.; ...

2014-12-30

The precursor plasmas from low wire number cylindrical wire arrays (CWAs) were previously shown to radiate at temperatures >300 eV for Ni-60 (94% Cu and 6% Ni) wires in experiments on the 1-MA Zebra generator. Continued research into precursor plasmas has studied additional midatomic-number materials including Cu and Alumel (95% Ni, 2% Al, 2% Mn, and 1% Si) to determine if the >300 eV temperatures are common for midatomic-number materials. Additionally, current scaling effects were observed by performing CWA precursor experiments at an increased current of 1.5 MA using a load current multiplier. Our results show an increase in amore » linear radiation yield of ~50% (16 versus 10 kJ/cm) for the experiments at increased current. However, plasma conditions inferred through the modeling of X-ray time-gated spectra are very similar for the precursor plasma in both current conditions.« less

Dual-Wavelength Interferometry and Light Emission Study for Experimental Support of Dual-Wire Ablation Experiments

NASA Astrophysics Data System (ADS)

Hamilton, Andrew; Caplinger, James; Sotnikov, Vladimir; Sarkisov, Gennady; Leland, John

2017-10-01

In the Plasma Physics and Sensors Laboratory, located at Wright Patterson Air Force Base, we utilize a pulsed power source to create plasma through a wire ablation process of metallic wires. With a parallel arrangement of wires the azimuthal magnetic fields generated around each wire, along with the Ohmic current dissipation and heating occurring upon wire evaporation, launch strong radial outflows of magnetized plasmas towards the centralized stagnation region. It is in this region that we investigate two phases of the wire ablation process. Observations in the first phase are collsionless and mostly comprised of light ions ejected from the initial corona. The second phase is observed when the wire core is ablated and heavy ions dominate collisions in the stagnation region. In this presentation we will show how dual-wavelength interferometric techniques can provide information about electron and atomic densities from experiments. Additionally, we expect white-light emission to provide a qualitative confirmation of the instabilities observed from our experiments. The material is based upon work supported by the Air Force Office of Scientific Research under Award Number 16RYCOR289.

Study of ablation and implosion stages in wire arrays using coupled ultraviolet and X-ray probing diagnostics

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

Anderson, A. A.; Ivanov, V. V.; Astanovitskiy, A. L.

2015-11-15

Star and cylindrical wire arrays were studied using laser probing and X-ray radiography at the 1-MA Zebra pulse power generator at the University of Nevada, Reno. The Leopard laser provided backlighting, producing a laser plasma from a Si target which emitted an X-ray probing pulse at the wavelength of 6.65 Å. A spherically bent quartz crystal imaged the backlit wires onto X-ray film. Laser probing diagnostics at the wavelength of 266 nm included a 3-channel polarimeter for Faraday rotation diagnostic and two-frame laser interferometry with two shearing interferometers to study the evolution of the plasma electron density at the ablation and implosionmore » stages. Dynamics of the plasma density profile in Al wire arrays at the ablation stage were directly studied with interferometry, and expansion of wire cores was measured with X-ray radiography. The magnetic field in the imploding plasma was measured with the Faraday rotation diagnostic, and current was reconstructed.« less

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

Greenly, John B.; Seyler, Charles

Experimental and computational studies of high energy density plasma streams ablated from fine wires. Laboratory of Plasma Studies, School of Electrical and Computer Engineering, Cornell University. Principal Investigators: Dr. John B. Greenly and Dr. Charles E. Seyler. This report summarizes progress during the final year of this project to study the physics of high energy density (HED) plasma streams of 10^17-10^20/cm3 density and high velocity (~100-500 km/s). Such streams are produced from 5-250 micrometer diameter wires heated and ionized by a 1 MA, 250 ns current pulse on the COBRA pulsed power facility at Cornell University. Plasma is ablated frommore » the wires and is driven away to high velocity by unbalanced JxB force. A wire, or an array of wires, can persist as an essentially stationary, continuous source of this streaming plasma for >200 ns, even with driving magnetic fields of many Tesla and peak current densities in the plasma of many MA/cm2. At the heart of the ablation stream generation is the continuous transport of mass from the relatively cold, near-solid-density wire "core" into current-carrying plasma within 1 mm of the wire, followed by the magnetic acceleration of that plasma and its trapped flux to form a directed stream. In the first two years of this program, an advancing understanding of ablation physics led to the discovery of several novel wire ablation experimental regimes. In the final year, one of these new HED plasma regimes has been studied in quantitative detail. This regime studies highly reproducible magnetic reconnection in strongly radiating plasma with supersonic and superalfvenic flow, and shock structures in the outflow. The key discovery is that very heavy wires, e.g. 250 micrometer diameter Al or 150 micrometer Cu, behave in a qualitatively different way than the lighter wires typically used in wire-array Z-pinches. Such wires can be configured to produce a static magnetic X-point null geometry that stores magnetic and thermal energy; reconnection and outflow are triggered when the current begins to decrease and the electric field reverses. The reconnecting flow is driven by both magnetic and thermal pressure forces, and it has been found to be possible to vary the configuration so that one or the other dominates. The magnetic null extends into a current sheet that is heated and radiates strongly, with supersonic outflows. This is the first study of reconnection in this HED plasma regime. This compressible, radiative regime, and the triggering mechanism, may be relevant to solar and astrophysical processes. The PERSEUS extended MHD code has been developed for simulation of these phenomena, and will continue to be used and further developed to help interpret and understand experimental results, as well as to guide experimental design. The code is well-suited to simulations of shocks, and includes Hall and electron inertia physics that appear to be of importance in a number of ablation flow regimes, and definitely in the reconnection regime when gradient scales are comparable to the ion inertial scale. During the final year, our graduate student supported by this grant completed a new version of PERSEUS with the finite volume computational scheme replaced by a discontinuous Galerkin method that gives much less diffusive behavior and allows faster run time and higher spatial resolution. Thecode is now being used to study shock structures produced in the outflow region of the reconnection regime.« less

Influence of the Al wire placed in the anode axis on the transformation of the deuterium plasma column in the plasma focus discharge

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

Kubes, P.; Cikhardtova, B.; Cikhardt, J.

In this paper, we describe the influence of an Al wire of 270 μm in diameter placed along the anode axis on the transformation of the deuterium pinch column in a megaampere (MA) plasma focus device. The evolution of the pinched column and of the wire corona was investigated by means of the multiframe interferometry, neutron and X-ray diagnostics. The wire corona did not influence considerably on the evolution of dense plasma structures and neutron production, but it increased the plasma density and consequently, the currents around its surface. The distribution of the closed internal currents (ranging hundreds of kA) andmore » associated magnetic fields amounting to 5 T were also estimated in the dense plasma column and in plasmoidal structures at the near-equilibrium state. The description is based on the balance of the plasma pressure and the pressure of the internal poloidal and toroidal current components compressed by the external pinched column. The dominant number of fusion deuterium-deuterium (D-D) neutrons is produced during the evolution of instabilities, when the uninterrupted wire corona (containing deuterium) connects the dense structures of the pinch, and it did not allow the formation of a constriction of the sub-millimeter diameter.« less

Shock-like pulse experiment in a strongly coupled dusty plasma

NASA Astrophysics Data System (ADS)

Kananovich, Anton; Goree, J.

2017-10-01

Compressional pulses are excited in a dusty plasma using a wire moved at a supersonic speed. The dusty plasma consists of a 2D monolayer of polymer microspheres electrically levitated in a low-temperature argon RF plasma. The microspheres gained a large negative charge so that they interacted with each other as a strongly coupled component, partly shielded by the electrons and ions. The wire, which had a negative potential that repelled microspheres, was moved at a constant speed, causing a compressional pulse to propagate. This pulse had shock-like properties because the wire was moved faster than the longitudinal sound speed in the microspheres. The experiment was repeated for the dusty plasma both in liquid and solid states, all of the controlled parameters except for the dust kinetic temperature being equal. The laser rastering method was used to change the kinetic temperature. Several experimental runs were done with different wire speeds for the both cases. An increase in the wire propagation speed increased the propagation speed of the compressional pulse. High pulse propagation speeds were obtained with Mach numbers up to 5. For high pulse propagation speeds crystal buckling was observed. Video microscopy was the main diagnostic. Supported by U.S. Dept. of Energy.

Comparison of X-ray Radiation Process in Single and Nested Wire Array Implosions

NASA Astrophysics Data System (ADS)

Li, Z. H.; Xu, Z. P.; Yang, J. L.; Xu, R. K.; Guo, C.; Grabovsky, E. V.; Oleynic, G. M.; Smirnov, V. P.

2006-01-01

In order to understanding the difference between tungsten single-wire-array and tungsten nested-wire-array Z-pinches, we have measured the x-ray power, the temporal-spatial distributions of x-ray radiation from each of the two loads. The measurements were performed with 0.1mm spatial and 1 ns temporal resolutions at 2.5- and 3.5-MA currents. The experimental conditions, including wire material, number of wires, wire-array length, electrode design, and implosion time, remained unchanged from shot to shot. Analysis of the radiation power profiles suggests that the nested-wire-array radiate slightly less x-ray energy in relatively shorter time interval than the single wire-array, leading to a much greater x-ray power in nested-wire-array implosion. The temporal-spatial distributions of x-ray power show that in both cases, plasmas formed by wire-array ablation radiate not simultaneously along load axis. For nested-wire-array Z-pinch, plasmas near the anode begin to radiate in 2ns later than that near the cathode. As a contrast, the temporal divergence of radiation among different plasma zones of single-wire-array Z-pinch along Z-axis is more than 6ns. Measurements of the x-ray emissions from small segments of pinch (2mm length along axis) indicate that local radiation power profiles almost do not vary for the two loads. Photographs taken by X-ray framing camera give a same description about the radiation process of pinch. One may expect that, as a result of this study, if the single-wire-array can be redesigned so ingeniously that the x-rays are emitted at the same time all over the pinch zone, the radiation power of single wire array Z-pinch may be much greater than what have been achieved.

The study of hard x-ray emission and electron beam generation in wire array Z-pinch and X-pinch plasmas at university-scale generators

NASA Astrophysics Data System (ADS)

Shrestha, Ishor Kumar

The studies of hard x-ray (HXR) emission and electron beam generation in Z-pinch plasmas are very important for Inertial Confinement Fusion (ICF) research and HXR emission application for sources of K-shell and L-shell radiation. Energetic electron beams from Z-pinch plasmas are potentially a problem in the development of ICF. The electron beams and the accompanying HXR emission can preheat the fuel of a thermonuclear target, thereby preventing the fuel compression from reaching densities required for the ignition of a fusion reaction. The photons above 3-4 keV radiated from a Z pinch can provide detailed information about the high energy density plasmas produced at stagnation. Hence, the investigation of characteristics of hard x-rays and electron beams produced during implosions of wire array loads on university scale-generators may provide important data for future ICF, sources of K-shell and L-shell radiations and basic plasma research. This dissertation presents the results of experimental studies of HXR and electron beam generation in wire-array and X-pinch on the 1.7 MA, 100-ns current rise time Zebra generator at University of Nevada, Reno and 1-MA 100-ns current rise-time Cornell Beam Research Accelerator (COBRA) at Cornell University. The experimental study of characteristics of HXR produced by multi-planar wire arrays, compact cylindrical wire array (CCWA) and nested cylindrical wire array (NCWA) made from Al, Cu, Mo, Ag, W and Au were analyzed. The dependence of the HXR yield and power on geometry of the load, the wire material, and load mass was observed. The presence of aluminum wires in the load with the main material such as stainless steel, Cu, Mo, Ag, W or Au in combined wire array decreases HXR yield. The comparison of emission characteristics of HXR and generation of electron beams in CCWA and NCWA on both the high impedance Zebra generator and low impedance COBRA generator were investigated. Some of the "cold" K- shell spectral lines (0.7-2.3Á) and cold L-shell spectral lines (1-1.54Á) in the HXR region were observed only during the interaction of electron beam with load material and anode surface. These observations suggest that the mechanism of HXR emission should be associated with non-thermal mechanisms such as the interaction of the electron beam with the load material. In order to estimate the characteristics of the high-energetic electron beam in Z-pinch plasmas, a hard x-ray polarimeter (HXP) has been developed and used in experiments on the Zebra generator. The electron beams (energy more than 30keV) have been investigated with measurements of the polarization state of the emitted bremsstrahlung radiation from plasma. We also analyzed characteristics of energetic electron beams produced by implosions of multi-planar wire arrays, compact cylindrical and nested wire arrays as well as X-pinches. Direct indications of electron beams (electron cutoff energy EB from 42-250 keV) were obtained by using the measured current of a Faraday cup placed above the anode or mechanical damage observed in the anode surface. A comparison of total electron beam energy and the spatial and spectral analysis of the parameters of plasmas were investigated for different wire materials. The dependences of the total electron beam energy (E b) on the wire material and the geometry of the wire array load were studied.

Radiation from mixed multi-planar wire arrays

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

Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.

2014-03-15

The study of radiation from different wire materials in wire array Z-pinch plasma is a very challenging topic because it is almost impossible to separate different plasmas at the stagnation. A new approach is suggested based on planar wire array (PWA) loads to assess this problem. Multi-planar wire arrays are implemented that consist of few planes, each with the same number of wires and masses but from different wire materials, arranged in parallel rows. In particular, the experimental results obtained with triple PWAs (TPWAs) on the UNR Zebra generator are analyzed with Wire Ablation Dynamics Model, non-local thermodynamic equilibrium kineticmore » model, and 2D radiation magneto-hydrodynamic to illustrate this new approach. In TPWAs, two wire planes were from mid-atomic-number wire material and another plane was from alloyed Al, placed either in the middle or at the edge of the TPWA. Spatial and temporal properties of K-shell Al and L-shell Cu radiations were analyzed and compared from these two configurations of TPWAs. Advantages of the new approach are demonstrated and future work is discussed.« less

Pressure Measurements for Tungsten Wire Explosions in Water

NASA Astrophysics Data System (ADS)

Afanas'ev, V. N.

2005-07-01

Successful wire array implosion experiments carried out on PBFA- Z accelerator [1], in which a record-breaking soft x-ray yield of more than 1.5 MJ was observed, stimulated interest in research of electric explosion of thin metal wires. The results of pressure measurements micron's tungsten wire explosion, which carried out in deionized water. Thin tungsten wire explosion was investigated experimentally at current pulse 100 ns duration. The shock waves from the 70 μm tungsten wire explosion were measured by the piezoceramic pressure gauge. The gauges were placed at a range from 3 to 15 mm of wire. The piezoceramic gauges were calibrated on the stable electron beams generator with nanoseconds duration. Experiments were carried out for verifying the tungsten plasma equation of state parameters under different values of the deposited energy. [1] R. B. Spielman, C. Deeney, G. A. Chandler et al., Phys.Plasmas #5, ð. 2105, 1998. The work was supported by ISTC # 1826

Pulse Power Compression by Cutting a Dense Z-Pinch with a Laser Beam

NASA Astrophysics Data System (ADS)

Winterberg, F.

1999-07-01

A thin cut made through a z-pinch by an intense laser beam can become a magnetically insulated diode crossed by an intense ion beam. For larger cuts, the gap is crossed by an intense relativistic electron beam, stopped by magnetic bremsstrahlung resulting in a pointlike intense x-ray source. In either case, the impedance of the pinch discharge is increased, with the power delivered rising in the same pro-portion. A magnetically insulated cut is advantageous for three reasons: First, with the ion current com-parable to the Alfvèn ion current, the pinch instabilities are reduced. Second, with the energy deposit-ed into fast ions, a non-Maxwellian velocity distribution is established increasing<σ ν> value for nuclear fusion reactions taking place in the pinch discharge. Third, in a high density z-pinch plasma, the intense ion beam can launch a thermonuclear detonation wave propagating along the pinch discharge channel. For larger cuts the soft x-rays produced by magnetic bremsstrahlung can be used to drive a thermonuclear hohlraum target. Finally, the proposed pulse power compression scheme permits to use a cheap low power d.c. source charging a magnetic storage coil delivering the magnetically stored energy to the pinch discharge load by an exploding wire opening switch.

Experiments on Plasma Turbulence Created by Supersonic Plasma Flows with Shear

DTIC Science & Technology

2014-04-01

for producing a plasma column (in black). An insulated wire traverses the plasma and car - ries a pulsed current in x-direction. The unmagnetized ions... electric field which together with the B field around the wire causes an electron ExB drift. The ions are unmagnetized. A radial space charge electric field...by the self-consistent currents passing through the grid. These currents, consisting of electron and ion flows, are controlled by the electrical

Recent advances in theoretical and numerical studies of wire array Z-pinch in the IAPCM

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

Ding, Ning, E-mail: ding-ning@iapcm.ac.cn; Zhang, Yang, E-mail: ding-ning@iapcm.ac.cn; Xiao, Delong, E-mail: ding-ning@iapcm.ac.cn

2014-12-15

Fast Z-pinch has produced the most powerful X-ray radiation source in laboratory and also shows the possibility to drive inertial confinement fusion (ICF). Recent advances in wire-array Z-pinch researches at the Institute of Applied Physics and Computational Mathematics are presented in this paper. A typical wire array Z-pinch process has three phases: wire plasma formation and ablation, implosion and the MRT instability development, stagnation and radiation. A mass injection model with azimuthal modulation coefficient is used to describe the wire initiation, and the dynamics of ablated plasmas of wire-array Z-pinches in (r, θ) geometry is numerically studied. In the implosionmore » phase, a two-dimensional(r, z) three temperature radiation MHD code MARED has been developed to investigate the development of the Magneto-Rayleigh-Taylor(MRT) instability. We also analyze the implosion modes of nested wire-array and find that the inner wire-array is hardly affected before the impaction of the outer wire-array. While the plasma accelerated to high speed in the implosion stage stagnates on the axis, abundant x-ray radiation is produced. The energy spectrum of the radiation and the production mechanism are investigated. The computational x-ray pulse shows a reasonable agreement with the experimental result. We also suggest that using alloyed wire-arrays can increase multi-keV K-shell yield by decreasing the opacity of K-shell lines. In addition, we use a detailed circuit model to study the energy coupling between the generator and the Z-pinch implosion. Recently, we are concentrating on the problems of Z-pinch driven ICF, such as dynamic hohlraum and capsule implosions. Our numerical investigations on the interaction of wire-array Z-pinches on foam convertors show qualitative agreements with experimental results on the “Qiangguang I” facility. An integrated two-dimensional simulation of dynamic hohlraum driven capsule implosion provides us the physical insights of wire-array plasma acceleration, shock generation and production, hohlraum formation, radiation ablation and fuel compression.« less

Real-time monitoring of the laser hot-wire welding process

NASA Astrophysics Data System (ADS)

Liu, Wei; Liu, Shuang; Ma, Junjie; Kovacevic, Radovan

2014-04-01

The laser hot-wire welding process was investigated in this work. The dynamics of the molten pool during welding was visualized by using a high-speed charge-coupled device (CCD) camera assisted by a green laser as an illumination source. It was found that the molten pool is formed by the irradiation of the laser beam on the filler wire. The effect of the hot-wire voltage on the stability of the welding process was monitored by using a spectrometer that captured the emission spectrum of the laser-induced plasma plume. The spectroscopic study showed that when the hot-wire voltage is above 9 V a great deal of spatters occur, resulting in the instability of the plasma plume and the welding process. The effect of spatters on the plasma plume was shown by the identified spectral lines of the element Mn I. The correlation between the Fe I electron temperature and the weld-bead shape was studied. It was noted that the electron temperature of the plasma plume can be used to real-time monitor the variation of the weld-bead features and the formation of the weld defects.

Diagnosis of femtosecond plasma filament by channeling microwaves along the filament

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

Alshershby, Mostafa; Ren, Yu; Qin, Jiang

2013-05-20

We introduce a simple, fast, and non-intrusive experimental method to obtain the basic parameters of femtosecond laser-generated plasma filament. The method is based on the channeling of microwaves along both a plasma filament and a well-defined conducting wire. By comparing the detected microwaves that propagate along the plasma filament and a copper wire with known conductivity and spatial dimension, the basic parameters of the plasma filament can be easily obtained. As a result of the possibility of channeling microwave radiation along the plasma filament, we were then able to obtain the plasma density distribution along the filament length.

Exploding Pusher Targets for Electron-Ion Coupling Measurements

NASA Astrophysics Data System (ADS)

Whitley, Heather D.; Pino, Jesse; Schneider, Marilyn; Shepherd, Ronnie; Benedict, Lorin; Bauer, Joseph; Graziani, Frank; Garbett, Warren

2015-11-01

Over the past several years, we have conducted theoretical investigations of electron-ion coupling and electronic transport in plasmas. In the regime of weakly coupled plasmas, we have identified models that we believe describe the physics well, but experimental data is still needed to validate the models. We are currently designing spectroscopic experiments to study electron-ion equilibration and/or electron heat transport using exploding pusher (XP) targets for experiments at the National Ignition Facility. Two platforms are being investigated: an indirect drive XP (IDXP) with a plastic ablator and a polar-direct drive XP (PDXP) with a glass ablator. The fill gas for both designs is D2. We propose to use a higher-Z dopant, such as Ar, as a spectroscopic tracer for time-resolved electron and ion temperature measurements. We perform 1D simulations using the ARES hydrodynamic code, in order to produce the time-resolved plasma conditions, which are then post-processed with CRETIN to assess the feasibility of a spectroscopic measurement. We examine target performance with respect to variations in gas fill pressure, ablator thickness, atom fraction of the Ar dopant, and drive energy, and assess the sensitivity of the predicted spectra to variations in the models for electron-ion equilibration and thermal conductivity. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-675219.

Experimental verification of the vaporization's contribution to the shock waves generated by underwater electrical wire explosion under micro-second timescale pulsed discharge

NASA Astrophysics Data System (ADS)

Han, Ruoyu; Zhou, Haibin; Wu, Jiawei; Clayson, Thomas; Ren, Hang; Wu, Jian; Zhang, Yongmin; Qiu, Aici

2017-06-01

This paper studies pressure waves generated by exploding a copper wire in a water medium, demonstrating the significant contribution of the vaporization process to the formation of shock waves. A test platform including a pulsed current source, wire load, chamber, and diagnostic system was developed to study the shock wave and optical emission characteristics during the explosion process. In the experiment, a total of 500 J was discharged through a copper wire load 0.2 mm in diameter and 4 cm in length. A water gap was installed adjacent to the load so that the current was diverted away from the load after breakdown occurred across the water gap. This allows the electrical energy injection into the load to be interrupted at different times and at different stages of the wire explosion process. Experimental results indicate that when the load was bypassed before the beginning of the vaporization phase, the measured peak pressure was less than 2.5 MPa. By contrast, the peak pressure increased significantly to over 6.5 MPa when the water gap broke down after the beginning of the vaporization phase. It was also found that when bypassing the load after the voltage peak, similar shock waves were produced to those from a non-bypassed load. However, the total optical emission of these bypassed loads was at least an order of magnitude smaller. These results clearly demonstrate that the vaporization process is vital to the formation of shock waves and the energy deposited after the voltage collapse may only have a limited effect.

Enhancing the x-ray output of a single-wire explosion with a gas-puff based plasma opening switch

NASA Astrophysics Data System (ADS)

Engelbrecht, Joseph T.; Ouart, Nicholas D.; Qi, Niansheng; de Grouchy, Philip W.; Shelkovenko, Tatiana A.; Pikuz, Sergey A.; Banasek, Jacob T.; Potter, William M.; Rocco, Sophia V.; Hammer, David A.; Kusse, Bruce R.; Giuliani, John L.

2018-02-01

We present experiments performed on the 1 MA COBRA generator using a low density, annular, gas-puff z-pinch implosion as an opening switch to rapidly transfer a current pulse into a single metal wire on axis. This gas-puff on axial wire configuration was studied for its promise as an opening switch and as a means of enhancing the x-ray output of the wire. We demonstrate that current can be switched from the gas-puff plasma into the wire, and that the timing of the switch can be controlled by the gas-puff plenum backing pressure. X-ray detector measurements indicate that for low plenum pressure Kr or Xe shots with a copper wire, this configuration can offer a significant enhancement in the peak intensity and temporal distribution of radiation in the 1-10 keV range.

Study of soft X-ray emission during wire array implosion under plasma focus conditions at the PF-3 facility

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

Dan’ko, S. A.; Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Krauz, V. I.

2015-11-15

Results of measurements of soft X-ray emission with photon energies of <1 keV under conditions of a plasma focus (PF) experiment are presented. The experiments were carried out at the world’s largest PF device—the PF-3 Filippov-type facility (I ⩽ 3 MA, T/4 ≈ 15–20 µs, W{sub 0} ⩽ 3 MJ). X-ray emission from both a discharge in pure neon and with a tungsten wire array placed on the axis of the discharge chamber was detected. The wire array imploded under the action of the electric current intercepted from the plasma current sheath of the PF discharge in neon. The measuredmore » soft X-ray powers from a conventional PF discharge in gas and a PF discharge in the presence of a wire array were compared for the first time.« less

Corrosion resistance of premodeled wires made of stainless steel used for heart electrotherapy leaders

NASA Astrophysics Data System (ADS)

Przondziono, J.; Walke, W.; Młynarski, R.; Szatka, W.

2012-05-01

The purpose of the study is to evaluate resistance to electrochemical corrosion of wire made of X10CrNi18-8 stainless steel designed for use in cardiology treatment. The influence of strain formed in the premodeling process and methods of wire surface preparation to corrosive resistance in artificial plasma solution were analysed. Wire corrosion tests were carried out in the solution of artificial plasma. Resistance to electrochemical corrosion was evaluated on the ground of recorded curves of anodic polarization by means of potentiodynamic method. Potentiodynamic tests carried out enabled to determine how the resistance to pitting corrosion of wire changes, depending on strain formed in the premodeling process as well as on the method of wire surface preparation. For evaluation of phenomena occurring on the surface of tested steel, electrochemical impedance spectroscopy (EIS) was applied. Deterioration of corrosive properties of wire along with the increase in the formed strain hardening was observed.

High velocity pulsed wire-arc spray

NASA Technical Reports Server (NTRS)

Kincaid, Russell W. (Inventor); Witherspoon, F. Douglas (Inventor); Massey, Dennis W. (Inventor)

1999-01-01

Wire arc spraying using repetitively pulsed, high temperature gas jets, usually referred to as plasma jets, and generated by capillary discharges, substantially increases the velocity of atomized and entrained molten droplets. The quality of coatings produced is improved by increasing the velocity with which coating particles impact the coated surface. The effectiveness of wire-arc spraying is improved by replacing the usual atomizing air stream with a rapidly pulsed high velocity plasma jet. Pulsed power provides higher coating particle velocities leading to improved coatings. 50 micron aluminum droplets with velocities of 1500 m/s are produced. Pulsed plasma jet spraying provides the means to coat the insides of pipes, tubes, and engine block cylinders with very high velocity droplet impact.

Electrostatic and electrodynamic response properties of nanostructures

NASA Astrophysics Data System (ADS)

Ayaz, Yuksel

1999-11-01

This thesis addresses the problem of nanostructure dielectric response to excitation by electric fields, both in the electrostatic c→infinity and the electrodynamic regimes. The nanostructures treated include planar quantum wells and quantum wires embedded in the vicinity of the bounding surface of the host semiconductor medium. Various cases are analyzed, including a single well or wire, a double well or wire, a lattice of N wells or wires and an infinite superlattice of wells or wires. The host medium is considered to have phonons and/or a bulk semiconductor plasma which interact with the plasmons of the embedded quantum wells or wires, and the host plasma is treated in both the local "cold" plasma regime and the nonlocal "hot" plasma regime. New hybridized quantum plasma collective modes emerge from these studies. The techniques employed here include the variational differential formulation of integral equations for the inverse dielectric function (in electrostatic case) and the dyadic Green's function (in the electrodynamic case) for the various systems described above. These integral equations are then solved in frequency-position representation by a variety of techniques depending on the geometrical features of the particular problem. Explicit closed form solutions for the inverse dielectric function or dyadic Green's function facilitate identification of the coupled collective modes in terms of their frequency poles, and the residues at the pole positions provide the relative amplitudes with which these normal modes respond to external excitation. Interesting features found include, for example, explicit formulas showing the transference of coupling of a two dimensional (2D) quantum well plasmon from a surface phonon to a bulk phonon as the 2D quantum well is displaced away from the bounding surface, deeper into the medium.

New Regimes of Implosions of Larger Sized Wire Arrays With and Without Modified Central Plane at 1.5-1.7 MA Zebra

NASA Astrophysics Data System (ADS)

Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Stafford, A.; Keim, S. F.; Petkov, E. E.; Lorance, M.; Chuvatin, A. S.; Coverdale, C. A.; Jones, B.

2013-10-01

The recent experiments at 1.5-1.7 MA on Zebra at UNR with larger sized planar wires arrays (compared to the wire loads at 1 MA current) have demonstrated higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions. Such multi-planar wire arrays had two outer wire planes from mid-Z material to create a global magnetic field (gmf) and mid-Z plasma flow between them. Also, they included a modified central plane with a few Al wires at the edges to influence gmf and to create Al plasma flow in the perpendicular direction. The stationary shock waves which existed over tens of ns on shadow images and the early x-ray emissions before the PCD peak on time-gated spectra were observed. The most recent experiments with similar loads but without the central wires demonstrated a very different regime of implosion with asymmetrical jets and no precursor formation. This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984 and in part by DE-FC52-06NA27616. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Numerical modelling of ozone production in a wire-cylinder corona discharge and comparison with a wire-plate corona discharge

NASA Astrophysics Data System (ADS)

Wang, Pengxiang; Chen, Junhong

2009-02-01

The effect of electrode configuration on ozone production in the direct-current corona discharge of dry and humid air is studied by a numerical model that combines the electron distribution in the corona plasma, plasma chemistry and transport phenomena. Two electrode configurations are considered: wire-cylinder discharge with air flowing along the wire axis and wire-plate discharge with air flowing transverse to the wire. The ozone distributions in both types of discharges are compared. For both electrode configurations, the ozone production rate is higher in the negative corona than in the positive corona and it decreases with an increase in relative humidity. More importantly, the detailed ozone distribution in the neighbourhood of the discharge wire, together with the ozone kinetics, reveals the possible difference in the ozone production from the two discharges. With the same operating conditions and sufficiently short flow residence time, the ozone production rate is nearly the same for both electrode configurations. When the flow residence time is longer than the characteristic time for homogeneous ozone destruction, the net ozone production is higher in the wire-cylinder discharge than in the wire-plate discharge due to relatively less ozone destruction.

Effects of space plasma discharge on the performance of large antenna structures in low Earth orbit

NASA Technical Reports Server (NTRS)

Blume, Hans-Juergen C.

1987-01-01

The anomalous plasma around spacecrafts in low Earth orbit represents the coma of an artificial comet. The plasma discharge is caused by an energetic disturbance of charged particles which were formerly in a state of equilibrium. The plasma can effect the passive and active radio frequency operation of large space antennas by inducing corona discharge or strong arcing in the antenna feeds. One such large space antenna is the 15-meter hoop column antenna which consists of a mesh membrane material (tricot knitted gold plated wire) reflector and carbon fiber tension cords. The atomic oxygen in the plasma discharge state can force the wire base metal particles through the gold lattice and oxydize the metal particles to build a Schottky-barrier contact at the point where the wires meet. This effect can cause strong deviations in the reflector performance in terms of antenna pattern and losses. Also, the carbon-fiber cords can experience a strength reduction of 30 percent over a 40-hour exposure time.

Real-time monitoring of laser hot-wire cladding of Inconel 625

NASA Astrophysics Data System (ADS)

Liu, Shuang; Liu, Wei; Harooni, Masoud; Ma, Junjie; Kovacevic, Radovan

2014-10-01

Laser hot-wire cladding (LHWC), characterized by resistance heating of the wire, largely increases the productivity and saves the laser energy. However, the main issue of applying this method is the occurrence of arcing which causes spatters and affects the stability of the process. In this study, an optical spectrometer was used for real-time monitoring of the LHWC process. The corresponding plasma intensity was analyzed under various operating conditions. The electron temperature of the plasma was calculated for elements of nickel and chromium that mainly comprised the plasma plume. There was a correlation between the electron temperature and the stability of the process. The characteristics of the resulted clad were also investigated by measuring the dilution, hardness and microstructure.

Cross-field electron transport inside an insulating cylinder of a baffled probe

NASA Astrophysics Data System (ADS)

Raitses, Yevgeny; Alt, Andrew

2017-10-01

Plasma-immersed wall experiments have been performed in a magnetized xenon plasma in a cross-field Penning configuration with density around 1012 cm-3 and an electron temperature around a few eV. A cylinder with an open end and diameter of 1.4 mm was placed across field lines so that electrons were blocked from reaching a wire recessed behind the shield while ions were unimpeded. The reduction of electron current to the wire causes it to float closer to the plasma potential, possibly making a device that can passively measure plasma potential. However, the measured electron current was much higher than expected even when the wire was recessed several electron gyroradii behind the baffle. Possible mechanisms for this electron conduction causing the short circuiting to the bulk plasma have been studied with numerical approaches and with a dedicated experiment designed to isolate this short circuit effect. The obtained results may be important for cross-field transport in a variety of other configurations in magnetized, low-temperature plasmas. This work was supported by DOE contract DE-AC02-09CH11466.

Propagation velocities of laser-produced plasmas from copper wire targets and water droplets

NASA Technical Reports Server (NTRS)

Song, Kyo-Dong; Alexander, Dennis R.

1994-01-01

Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire target (75 microns diameter) and water droplets (75 microns diameter) at irradiance levels ranging from 25 to 150 GW/sq cm. Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximately = 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/sq cm, the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(exp 5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/sq cm showed a quantitative agreement within approximately 50% while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma liquid droplets obtained by previous research are compared with current work.

The transfer of atmospheric-pressure ionization waves via a metal wire

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

Xia, Yang; Liu, Dongping, E-mail: Dongping.liu@dlnu.edu.cn; School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024

2016-01-15

Our study has shown that the atmospheric-pressure He ionization waves (IWs) may be transferred from one dielectric tube (tube 1) to the other one (tube 2) via a floating metal wire. The propagation of IWs along the two tubes is not affected by the diameter of a floating metal wire, however, their propagation is strongly dependent on the length of a floating metal wire. The propagation of one IW along the tube 1 may result in the second IW propagating reversely inside the tube in vicinity of a floating metal wire, which keeps from their further propagation through the tubemore » 1. After they merge together as one conduction channel inside the tube 1, the transferred plasma bullet starts to propagate along the tube 2. The propagation of transferred plasma bullets along the tube 2 is mainly determined by the capacitance and inductance effects, and their velocity and density can be controlled by the length of a floating metal wire.« less

Whistler mode refraction in highly nonuniform magnetic fields

NASA Astrophysics Data System (ADS)

Urrutia, J. M.; Stenzel, R.

2016-12-01

In a large laboratory plasma the propagation of whistler modes is measured in highly nonuniform magnetic fields created by a current-carrying wires. Ray tracing is not applicable since the wavelength and gradient scale length are comparable. The waves are excited with a loop antenna near the wire. The antenna launches an m=1 helicon mode in a uniform plasma. The total magnetic field consists of a weak uniform background field and a nearly circular field of a straight wire across the background field. A circular loop produces 3D null points and a 2D null line. The whistler wave propagation will be shown. It is relevant to whistler mode propagation in space plasmas near magnetic null-points, small flux ropes, lunar crustal magnetic fields and active wave injection experiments.

Satellite myths

NASA Astrophysics Data System (ADS)

Easton, Roger L.; Hall, David

2008-01-01

Richard Corfield's article “Sputnik's legacy” (October 2007 pp23-27) states that the satellite on board the US Vanguard rocket, which exploded during launch on 6 December 1957 two months after Sputnik's successful take-off, was “a hastily put together contraption of wires and circuitry designed only to send a radio signal back to Earth”. In fact, the Vanguard satellite was developed over a period of several years and put together carefully using the best techniques and equipment available at the time - such as transistors from Bell Laboratories/Western Electric. The satellite contained not one but two transmitters, in which the crystal-controlled oscillators had been designed to measure both the temperature of the satellite shell and of the internal package.

Investigation of longitudinal proton acceleration in exploded targets irradiated by intense short-pulse laser

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

Gauthier, M.; CEA, DAM, DIF, 91297 Arpajon; Lévy, A.

2014-01-15

It was recently shown that a promising way to accelerate protons in the forward direction to high energies is to use under-dense or near-critical density targets instead of solids. Simulations have revealed that the acceleration process depends on the density gradients of the plasma target. Indeed, under certain conditions, the most energetic protons are predicted to be accelerated by a collisionless shock mechanism that significantly increases their energy. We report here the results of a recent experiment dedicated to the study of longitudinal ion acceleration in partially exploded foils using a high intensity (∼5 × 10{sup 18} W/cm{sup 2}) picosecond laser pulse. Wemore » show that protons accelerated using targets having moderate front and rear plasma gradients (up to ∼8 μm gradient length) exhibit similar maximum proton energy and number compared to proton beams that are produced, in similar laser conditions, from solid targets, in the well-known target normal sheath acceleration regime. Particle-In-Cell simulations, performed in the same conditions as the experiment and consistent with the measurements, allow laying a path for further improvement of this acceleration scheme.« less

Shock ion acceleration by an ultrashort circularly polarized laser pulse via relativistic transparency in an exploded target.

PubMed

Kim, Young-Kuk; Cho, Myung-Hoon; Song, Hyung Seon; Kang, Teyoun; Park, Hyung Ju; Jung, Moon Youn; Hur, Min Sup

2015-10-01

We investigated ion acceleration by an electrostatic shock in an exploded target irradiated by an ultrashort, circularly polarized laser pulse by means of one- and three-dimensional particle-in-cell simulations. We discovered that the laser field penetrating via relativistic transparency (RT) rapidly heated the upstream electron plasma to enable the formation of a high-speed electrostatic shock. Owing to the RT-based rapid heating and the fast compression of the initial density spike by a circularly polarized pulse, a new regime of the shock ion acceleration driven by an ultrashort (20-40 fs), moderately intense (1-1.4 PW) laser pulse is envisaged. This regime enables more efficient shock ion acceleration under a limited total pulse energy than a linearly polarized pulse with crystal laser systems of λ∼1μm.

Focusing experiments in plasma coaxial railguns

NASA Astrophysics Data System (ADS)

Driga, M. D.; Cook, R. W.; Thelen, R. F.

1986-11-01

Results are reported from experiments on focusing of plasma fired from a coaxial electromagnetic gun (CEMG). The plasma used, obtained by exploding a metallic fuse at the gun breech, comprised metal vapor, metallic liquid droplets and small chunks of solid metal. An azimuthal current, and thereby an axial field, was introduced at the breech of the CEMG by a solenoid. Previous studies indicated that the field would cause vaporized metal to form into a self-stabilizing toroidal plasma. Test shots instrumented with Languir probes and pick-up coils did not reveal the presence of toroidal plasma rings. However, post-mortem of the 30 cm rail showed that only one-third of the 3 mg Al fuse metal remained in the bore. Further, a toroidal hole was punched in a diagnostic screen at the bore exit after one shot.

Studying Electromagnetic Beam Instabilities in Laser Plasmas for Alfvénic Parallel Shock Formation

NASA Astrophysics Data System (ADS)

Dorst, R. S.; Heuer, P. V.; Weidl, M. S.; Schaeffer, D. B.; Constantin, C. G.; Vincena, S.; Tripathi, S.; Gekelman, W.; Winske, D.; Niemann, C.

2017-10-01

We present measurements of the collisionless interaction between an exploding laser-produced plasma (LPP) and a large, magnetized ambient plasma. The LPP is created by focusing a high energy laser on a target embedded in the ambient Large Plasma Device (LAPD) plasma at the University of California, Los Angeles. The resulting super-Alfvénic (MA = 5) ablated material moves parallel to the background magnetic field (300 G) through 12m (80 δ i) of the LAPD, interacting with the ambient Helium plasma (ni = 9 ×1012 cm-3) through electromagnetic beam instabilities. The debris is characterized by Langmuir probes and a time-resolved fluorescence monochromator. Waves in the magnetic field produced by the instabilities are diagnosed by an array of 3-axis `bdot' magnetic field probes. Measurements are compared to hybrid simulations of both the experiment and of parallel shocks.

Shockwave generation by a semiconductor bridge operation in water

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

Zvulun, E.; Toker, G.; Gurovich, V. Tz.

2014-05-28

A semiconductor bridge (SCB) is a silicon device, used in explosive systems as the electrical initiator element. In recent years, SCB plasma has been extensively studied, both electrically and using fast photography and spectroscopic imaging. However, the value of the pressure buildup at the bridge remains unknown. In this study, we operated SCB devices in water and, using shadow imaging and reference beam interferometry, obtained the velocity of the shock wave propagation and distribution of the density of water. These results, together with a self-similar hydrodynamic model, were used to calculate the pressure generated by the exploding SCB. In addition,more » the results obtained showed that the energy of the water flow exceeds significantly the energy deposited into the exploded SCB. The latter can be explained by the combustion of the aluminum and silicon atoms released in water, which acts as an oxidizing medium.« less

Characterisation of an Exploding Foil Initiator (EFI) system

NASA Astrophysics Data System (ADS)

Davies, H. R.; Chapman, D. J.; Vine, T. A.; Proud, W. G.

2009-06-01

Exploding Foil Initiators (EFIs) provide a safe and reliable means of detonation of explosives. They are highly insensitive to mechanical shock and electrical interference, requiring a specific high current pulse for initiation. The use of only insensitive secondary explosives and not more sensitive primary explosives further improves safety. When a high current is passed through the metal bridge, a plasma is formed as the metal can not expand beyond the polymer film layer above. This causes the film to expand forming a bubble or shearing off to form a flyer. These flyers can then be used to initiate secondary explosives. Due to the very high speed at which these systems operate, high speed streak photography was used to characterise the behaviour of the polymer film flyers produced. This paper will report the preliminary findings on the mechanical, electrical and velocity changes seen in some proprietary systems.

Cable Discharge System for fundamental detonator studies

NASA Technical Reports Server (NTRS)

Peevy, Gregg R.; Barnhart, Steven G.; Brigham, William P.

1994-01-01

Sandia National Laboratories has recently completed the modification and installation of a cable discharge system (CDS) which will be used to study the physics of exploding bridgewire (EBW) detonators and exploding foil initiators (EFI or slapper). Of primary interest are the burst characteristics of these devices when subjected to the constant current pulse delivered by this system. The burst process involves the heating of the bridge material to a conductive plasma and is essential in describing the electrical properties of the bridgewire foil for use in diagnostics or computer models. The CDS described herein is capable of delivering up to an 8000 A pulse of 3 micron duration. Experiments conducted with the CDS to characterize the EBW and EFI burst behavior are also described. In addition, the CDS simultaneous VISAR capability permits updating the EFI electrical Gurney analysis parameters used in our computer simulation codes. Examples of CDS generated data for a typical EFI and EBW detonator are provided.

Wire-Guide Manipulator For Automated Welding

NASA Technical Reports Server (NTRS)

Morris, Tim; White, Kevin; Gordon, Steve; Emerich, Dave; Richardson, Dave; Faulkner, Mike; Stafford, Dave; Mccutcheon, Kim; Neal, Ken; Milly, Pete

1994-01-01

Compact motor drive positions guide for welding filler wire. Drive part of automated wire feeder in partly or fully automated welding system. Drive unit contains three parallel subunits. Rotations of lead screws in three subunits coordinated to obtain desired motions in three degrees of freedom. Suitable for both variable-polarity plasma arc welding and gas/tungsten arc welding.

Comparison of photoemission characteristics between square and circular wire array GaAs photocathodes.

PubMed

Deng, Wenjuan; Peng, Xincun; Zou, Jijun; Wang, Weilu; Liu, Yun; Zhang, Tao; Zhang, Yijun; Zhang, Daoli

2017-11-10

Two types of negative electron affinity gallium arsenide (GaAs) wire array photocathodes were fabricated by reactive ion etching and inductively coupled plasma etching of bulk GaAs material. High density GaAs wire arrays with high periodicity and good morphology were verified using scanning electron microscopy, and photoluminescence spectra confirmed the wire arrays had good crystalline quality. Reflection spectra showed that circular GaAs wire arrays had superior light trapping compared with square ones. However, after Cs/O activation, the square GaAs wire array photocathodes showed enhanced spectral response. The integral sensitivity of the square wire array photocathodes was approximately 2.8 times that of the circular arrays.

Current shunting and formation of stationary shock waves during electric explosions of metal wires in air

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

Ivanenkov, G. V.; Gus'kov, S. Yu.; Barishpol'tsev, D. V.

2010-01-15

Results of experiments on the generation of shock waves during electric explosions of fine copper and tungsten wires in air are analyzed. The generation mechanism of stationary shock wave by a plasma piston formed during the shunting breakdown of the electrode gap in the course of a wire explosion is investigated. The role of structural elements of such discharges, such as the core, corona, and wire environment, is analyzed.

Electrodynamic Tether

NASA Technical Reports Server (NTRS)

Johnson, Charles L. (Inventor); Ballance, Judy L. (Inventor); Welzyn, Kenneth J. (Inventor); Vaughn, Jason A. (Inventor); Lorenzini, Enrico (Inventor); Schuler, Peter S. (Inventor)

2006-01-01

A tether system for providing thrust to or power subsystems of an artificial satellite in a low earth orbit. The tether has three main sections, an insulated section connected to the satellite, a conducting section connected to the insulating section for drawing in and releasing electrons from the space plasma and a non-conducting section for providing a tension to the other sections of the tether. An oxygen resistant coating is applied to the bare wire of the conducting section as well as the insulated wires of the insulated section that prevents breakdown during tether operations in the space plasma. The insulated and bare wire sections also surround a high tensile flexible polymer core to prevent any debris from breaking the tether during use.

Observation of >400-eV precursor plasmas from low-wire-number copper arrays at the 1-MA zebra facility.

PubMed

Coverdale, C A; Safronova, A S; Kantsyrev, V L; Ouart, N D; Esaulov, A A; Deeney, C; Williamson, K M; Osborne, G C; Shrestha, I; Ampleford, D J; Jones, B

2009-04-17

Experiments with cylindrical copper wire arrays at the 1-MA Zebra facility show that high temperatures exist in the precursor plasmas formed when ablated wire array material accretes on the axis prior to the stagnation of a z pinch. In these experiments, the precursor radiated approximately 20% of the >1000 eV x-ray output, and time-resolved spectra show substantial emission from Cu L-shell lines. Modeling of the spectra shows an increase in temperature as the precursor forms, up to approximately 450 eV, after which the temperature decreases to approximately 220-320 eV until the main implosion.

Radiation characteristics and implosion dynamics of tungsten wire array Z-pinches on the YANG accelerator

NASA Astrophysics Data System (ADS)

Huang, Xian-Bin; Yang, Li-Bing; Li, Jing; Zhou, Shao-Tong; Ren, Xiao-Dong; Zhang, Si-Qun; Dan, Jia-Kun; Cai, Hong-Chun; Duan, Shu-Chao; Chen, Guang-Hua; Zhang, Zheng-Wei; Ouyang, Kai; Li, Jun; Zhang, Zhao-Hui; Zhou, Rong-Guo; Wang, Gui-Lin

2012-05-01

We investigated the radiation characteristics and implosion dynamics of low-wire-number cylindrical tungsten wire array Z-pinches on the YANG accelerator with a peak current 0.8-1.1 MA and a rising time ~ 90 ns. The arrays are made up of (8-32) × 5 μm wires 6/10 mm in diameter and 15 mm in height. The highest X-ray power obtained in the experiments was about 0.37 TW with the total radiation energy ~ 13 kJ and the energy conversion efficiency ~ 9% (24 × 5 μm wires, 6 mm in diameter). Most of the X-ray emissions from tungsten Z-pinch plasmas were distributed in the spectral band of 100-600 eV, peaked at 250 and 375 eV. The dominant wavelengths of the wire ablation and the magneto-Rayleigh—Taylor instability were found and analyzed through measuring the time-gated self-emission and laser interferometric images. Through analyzing the implosion trajectories obtained by an optical streak camera, the run-in velocities of the Z-pinch plasmas at the end of the implosion phase were determined to be about (1.3-2.1) × 107 cm/s.

Characteristics of the Plasma Source for Ground Ionosphere Simulation Surveyed by Disk-Type Langmuir Probe

NASA Astrophysics Data System (ADS)

Ryu, Kwangsun; Lee, Junchan; Kim, Songoo; Chung, Taejin; Shin, Goo-Hwan; Cha, Wonho; Min, Kyoungwook; Kim, Vitaly P.

2017-12-01

A space plasma facility has been operated with a back-diffusion-type plasma source installed in a mid-sized vacuum chamber with a diameter of 1.5 m located in Satellite Technology Research Center (SaTReC), Korea Advanced Institute of Science and Technology (KAIST). To generate plasma with a temperature and density similar to the ionospheric plasma, nickel wires coated with carbonate solution were used as filaments that emit thermal electrons, and the accelerated thermal electrons emitted from the heated wires collide with the neutral gas to form plasma inside the chamber. By using a disk-type Langmuir probe installed inside the vacuum chamber, the generation of plasma similar to the space environment was validated. The characteristics of the plasma according to the grid and plate anode voltages were investigated. The grid voltage of the plasma source is realized as a suitable parameter for manipulating the electron density, while the plate voltage is suitable for adjusting the electron temperature. A simple physical model based on the collision cross-section of electron impact on nitrogen molecule was established to explain the plasma generation mechanism.

Modeling and simulations of the double-probe electric field instrument in tenuous and cold streaming plasmas

NASA Astrophysics Data System (ADS)

Miyake, Y.; Cully, C. M.; Usui, H.; Nakashima, H.

2013-12-01

In order to increase accuracy and reliability of in-situ measurements made by scientific spacecraft, it is imperative to develop comprehensive understanding of spacecraft-plasma interactions. In space environments, not only the spacecraft charging but also surrounding plasma disturbances such as caused by the wake formation may interfere directly with in-situ measurements. The self-consistent solutions of such phenomena are necessary to assess their effects on scientific spacecraft systems. As our recent activity, we work on the modeling and simulations of Cluster double-probe instrument in tenuous and cold streaming plasmas [1]. Double-probe electric field sensors are often deployed using wire booms with radii much less than typical Debye lengths of magnetospheric plasmas (millimeters compared to tens of meters). However, in tenuous and cold streaming plasmas seen in the polar cap and lobe regions, the wire booms have a high positive potential due to photoelectron emission and can strongly scatter approaching ions. Consequently, an electrostatic wake formed behind the spacecraft is further enhanced by the presence of the wire booms. We reproduce this process for the case of the Cluster satellite by performing plasma particle-in-cell (PIC) simulations [2], which include the effects of both the spacecraft body and the wire booms in a simultaneous manner, on modern supercomputers. The simulations reveal that the effective thickness of the booms for the Cluster Electric Field and Wave (EFW) instrument is magnified from its real thickness (2.2 millimeters) to several meters, when the spacecraft potential is at 30-40 volts. Such booms enhance the wake electric field magnitude by a factor of about 2 depending on the spacecraft potential, and play a principal role in explaining the in situ Cluster EFW data showing sinusoidal spurious electric fields of about 10 mV/m amplitudes. The boom effects are quantified by comparing PIC simulations with and without wire booms. The paper also reports some recent progress of ongoing PIC simulation research that focuses on spurious electric field generation in subsonic ion flows. Our preliminary simulation results revealed that; (1) there is no apparent wake signature behind the spacecraft in such a condition, but (2) spurious electric field over 1 mV/m amplitude is observed in the direction of the flow vector. The observed field amplitude is sometimes comparable to the convection electric field (a few mV/m) associated with the flow. Our analysis also confirmed that the spurious field is caused by a weakly-asymmetric potential pattern created by the ion flow. We will present the parametric study of such spurious fields for various conditions of plasma flows. [References] [1] Miyake, Y., C. M. Cully, H. Usui, and H. Nakashima (2013), Plasma particle simulations of wake formation behind a spacecraft with thin wire booms, submitted to J. Geophys. Res. [2] Miyake, Y., and H. Usui (2009), New electromagnetic particle simulation code for the analysis of spacecraft-plasma interactions, Phys. Plasmas, 16, 062904, doi:10.1063/1.3147922.

All optical electron injector using an intense ultrashort pulse laser and a solid wire target

NASA Astrophysics Data System (ADS)

Palchan, T.; Eisenmann, S.; Zigler, A.; Kaganovich, D.; Hubbard, R. F.; Fraenkel, M.; Fisher, D.; Henis, Z.

2006-05-01

Energetic electron bunches were generated by irradiating a solid tungsten wire 13 μm wide with 50 femtosecond pulses at an intensity of ˜3×1018 W/cm2. The electron yield, energy spectrum and angular distribution were measured. These energetic electron bunches are suitable for injection into a laser driven plasma accelerator. An all-optical electron injector based on this approach could simplify timing and alignment in future laser-plasma accelerator experiments.

Experimental results from an X-ray imaging crystal spectrometer utilizing multi-wire proportional counter for KSTAR

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

Lee, S. G., E-mail: sglee@nfri.re.kr; Kim, Y. S.; Yoo, J. W.

2016-11-15

The inconsistency of the first experimental results from the X-ray imaging crystal spectrometer for the Korea Superconducting Tokamak Advanced Research device utilizing a multi-wire proportional counter (MWPC) is clarified after improving the photon-count rate of the data acquisition system for the MWPC and ground loop isolator for the whole spectrometer system. The improved MWPC is successfully applied to pure Ohmic plasmas as well as plasmas with high confinement modes.

Transfer of a cold atmospheric pressure plasma jet through a long flexible plastic tube

NASA Astrophysics Data System (ADS)

Kostov, Konstantin G.; Machida, Munemasa; Prysiazhnyi, Vadym; Honda, Roberto Y.

2015-04-01

This work proposes an experimental configuration for the generation of a cold atmospheric pressure plasma jet at the downstream end of a long flexible plastic tube. The device consists of a cylindrical dielectric chamber where an insulated metal rod that serves as high-voltage electrode is inserted. The chamber is connected to a long (up to 4 m) commercial flexible plastic tube, equipped with a thin floating Cu wire. The wire penetrates a few mm inside the discharge chamber, passes freely (with no special support) along the plastic tube and terminates a few millimeters before the tube end. The system is flushed with Ar and the dielectric barrier discharge (DBD) is ignited inside the dielectric chamber by a low frequency ac power supply. The gas flow is guided by the plastic tube while the metal wire, when in contact with the plasma inside the DBD reactor, acquires plasma potential. There is no discharge inside the plastic tube, however an Ar plasma jet can be extracted from the downstream tube end. The jet obtained by this method is cold enough to be put in direct contact with human skin without an electric shock. Therefore, by using this approach an Ar plasma jet can be generated at the tip of a long plastic tube far from the high-voltage discharge region, which provides the safe operation conditions and device flexibility required for medical treatment.

Dynamics of conical wire array Z-pinch implosions

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

Ampleford, D. J.; Lebedev, S. V.; Bland, S. N.

2007-10-15

A modification of the wire array Z pinch, the conical wire array, has applications to the understanding of wire array implosions and potentially to pulse shaping relevant to inertial confinement fusion. Results are presented from imploding conical wire array experiments performed on university scale 1 MA generators--the MAGPIE generator (1 MA, 240 ns) at Imperial College London [I. H. Mitchell et al., Rev. Sci Instrum. 67, 1533 (1996)] and the Nevada Terawatt Facility's Zebra generator (1 MA, 100 ns) at the University of Nevada, Reno [B. Bauer et al., in Dense Z-Pinches, edited by N. Pereira, J. Davis, and P.more » Pulsifer (AIP, New York, 1997), Vol. 409, p. 153]. This paper will discuss the implosion dynamics of conical wire arrays. Data indicate that mass ablation from the wires in this complex system can be reproduced with a rocket model with fixed ablation velocity. Modulations in the ablated plasma are present, the wavelength of which is invariant to a threefold variation in magnetic field strength. The axial variation in the array leads to a zippered precursor column formation. An initial implosion of a magnetic bubble near the cathode is followed by the implosion zippering upwards. Spectroscopic data demonstrating a variation of plasma parameters (e.g., electron temperature) along the Z-pinch axis is discussed, and experimental data are compared to magnetohydrodynamic simulations.« less

Optimization of the neutron yield in fusion plasmas produced by Coulomb explosions of deuterium clusters irradiated by a petawatt laser.

PubMed

Bang, W; Dyer, G; Quevedo, H J; Bernstein, A C; Gaul, E; Donovan, M; Ditmire, T

2013-02-01

The kinetic energy of hot (multi-keV) ions from the laser-driven Coulomb explosion of deuterium clusters and the resulting fusion yield in plasmas formed from these exploding clusters has been investigated under a variety of conditions using the Texas Petawatt laser. An optimum laser intensity was found for producing neutrons in these cluster fusion plasmas with corresponding average ion energies of 14 keV. The substantial volume (1-10 mm(3)) of the laser-cluster interaction produced by the petawatt peak power laser pulse led to a fusion yield of 1.6×10(7) neutrons in a single shot with a 120 J, 170 fs laser pulse. Possible effects of prepulses are discussed.

Uniformity of cylindrical imploding underwater shockwaves at very small radii

NASA Astrophysics Data System (ADS)

Yanuka, D.; Rososhek, A.; Bland, S. N.; Krasik, Ya. E.

2017-11-01

We compare the convergent shockwaves generated from underwater, cylindrical arrays of copper wire exploded by multiple kilo-ampere current pulses on nanosecond and microsecond scales. In both cases, the pulsed power devices used for the experiments had the same stored energy (˜500 J) and the wire mass was adjusted to optimize energy transfer to the shockwave. Laser backlit framing images of the shock front were achieved down to the radius of 30 μm. It was found that even in the case of initial azimuthal non-symmetry, the shock wave self-repairs in the final stages of its motion, leading to a highly uniform implosion. In both these and previous experiments, interference fringes have been observed in streak and framing images as the shockwave approached the axis. We have been able to accurately model the origin of the fringes, which is due to the propagation of the laser beam diffracting off the uniform converging shock front. The dynamics of the shockwave and its uniformity at small radii indicate that even with only 500 J stored energies, this technique should produce pressures above 1010 Pa on the axis, with temperatures and densities ideal for warm dense matter research.

Electromagnetic (EM) Wave Attachment to Laser Plasma Filaments

DTIC Science & Technology

2009-05-01

this phenomenon over a laboratory scale distance and observed that the channel energy, diameter, and modulated spectrum all remained relatively ...are oriented parallel to one another and insulated from one another to maintain a calculated separation. The TEM waves also represent plane waves...orientation, the electric field will point along the direction of the wire axis. The wire is 0.8 mm copper wire, fixed at both ends and insulated at

X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array source.

PubMed

Osborne, G C; Kantsyrev, V L; Safronova, A S; Esaulov, A A; Weller, M E; Shrestha, I; Shlyaptseva, V V; Ouart, N D

2012-10-01

Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature (∼10-40 eV) plasmas than emission spectra (∼350-500 eV).

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents

PubMed Central

Jung, Heesoo; Seo, Jin Ah; Choi, Seungki

2017-01-01

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design—wearable APP (WAPP)—that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents. PMID:28098192

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents

NASA Astrophysics Data System (ADS)

Jung, Heesoo; Seo, Jin Ah; Choi, Seungki

2017-01-01

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design—wearable APP (WAPP)—that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents.

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents.

PubMed

Jung, Heesoo; Seo, Jin Ah; Choi, Seungki

2017-01-18

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design-wearable APP (WAPP)-that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents.

Exploding dissipative solitons in the cubic-quintic complex Ginzburg-Landau equation in one and two spatial dimensions. A review and a perspective

NASA Astrophysics Data System (ADS)

Cartes, C.; Descalzi, O.; Brand, H. R.

2014-10-01

We review the work on exploding dissipative solitons in one and two spatial dimensions. Features covered include: the transition from modulated to exploding dissipative solitons, the analogue of the Ruelle-Takens scenario for dissipative solitons, inducing exploding dissipative solitons by noise, two classes of exploding dissipative solitons in two spatial dimensions, diffusing asymmetric exploding dissipative solitons as a model for a two-dimensional extended chaotic system. As a perspective we outline the interaction of exploding dissipative solitons with quasi one-dimensional dissipative solitons, breathing quasi one-dimensional solutions and their possible connection with experimental results on convection, and the occurence of exploding dissipative solitons in reaction-diffusion systems. It is a great pleasure to dedicate this work to our long-time friend Hans (Prof. Dr. Hans Jürgen Herrmann) on the occasion of his 60th birthday.

Laser based imaging of time depending microscopic scenes with strong light emission

NASA Astrophysics Data System (ADS)

Hahlweg, Cornelius; Wilhelm, Eugen; Rothe, Hendrik

2011-10-01

Investigating volume scatterometry methods based on short range LIDAR devices for non-static objects we achieved interesting results aside the intended micro-LIDAR: the high speed camera recording of the illuminated scene of an exploding wire -intended for Doppler LIDAR tests - delivered a very effective method of observing details of objects with extremely strong light emission. As a side effect a schlieren movie is gathered without any special effort. The fact that microscopic features of short time processes with high emission and material flow might be imaged without endangering valuable equipment makes this technique at least as interesting as the intended one. So we decided to present our results - including latest video and photo material - instead of a more theoretical paper on our progress concerning the primary goal.

50th Annual Fuze Conference.Session 3 and 4

DTIC Science & Technology

2006-05-11

Exploding Foil Initiator Research • Research on Explosives • Conclusion Wim Prinse Research Scientist3 TNO has organised...Research Scientist6 Exploding Foil Initiator Research • Electrical circuit • Exploding foil • Velocity of the flyer • Driver Explosive • Secondary...90% efficiency of energy deposited in the exploding foil (50 % other circuits) Wim Prinse Research Scientist8 Exploding foil • Dimension of the foil

Laser interferometry of radiation driven gas jets

NASA Astrophysics Data System (ADS)

Swanson, Kyle James; Ivanov, Vladimir; Mancini, Roberto; Mayes, Daniel C.

2017-06-01

In a series of experiments performed at the 1MA Zebra pulsed power accelerator of the Nevada Terawatt Facility nitrogen gas jets were driven with the broadband x-ray flux produced during the collapse of a wire-array z-pinch implosion. The wire arrays were comprised of 4 and 8, 10μm-thick gold wires and 17μm-thick nickel wires, 2cm and 3cm tall, and 0.3cm in diameter. They radiated 12kJ to 16kJ of x-ray energy, most of it in soft x-ray photons of less than 1keV of energy, in a time interval of 30ns. This x-ray flux was used to drive a nitrogen gas jet located at 0.8cm from the axis of the z-pinch radiation source and produced with a supersonic nozzle. The x-ray flux ionizes the nitrogen gas thus turning it into a photoionized plasma. We used laser interferometry to probe the ionization of the plasma. To this end, a Mach-Zehnder interferometer at the wavelength of 266 nm was set up to extract the atom number density profile of the gas jet just before the Zebra shot, and air-wedge interferometers at 266 and 532 nm were used to determine the electron number density of the plasma right during the Zebra shot. The ratio of electron to atom number densities gives the distribution of average ionization state of the plasma. A python code was developed to perform the image data processing, extract phase shift spatial maps, and obtain the atom and electron number densities via Abel inversion. Preliminary results from the experiment are promising and do show that a plasma has been created in the gas jet driven by the x-ray flux, thus demonstrating the feasibility of a new experimental platform to study photoionized plasmas in the laboratory. These plasmas are found in astrophysical scenarios including x-ray binaries, active galactic nuclei, and the accretion disks surrounding black holes1. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451.1R. C. Mancini et al, Phys. Plasmas 16, 041001 (2009)

Factors affecting energy deposition and expansion in single wire low current experiments

NASA Astrophysics Data System (ADS)

Duselis, Peter U.; Vaughan, Jeffrey A.; Kusse, Bruce R.

2004-08-01

Single wire experiments were performed on a low current pulse generator at Cornell University. A 220 nF capacitor charged to 15-25 kV was used to drive single wire experiments. The capacitor and wire holder were connected in series through an external variable inductor to control the current rise rate. This external series inductance was adjustable from 0.2 to 2 μH. When coupled with the range of charging voltages this results in current rise rates from 5 to 50 A/ns. The current heated the wire through liquid and vapor phases until plasma formed around the wire. Energy deposition and expansion rates were measured as functions of the current rise rate. These results indicated better energy deposition and higher expansion rates with faster current rise rates. Effects of the wire-electrode connection method and wire polarity were also studied.

Spectroscopic Analysis and Thomson Scattering Diagnostics of Wire Produced Plasma

NASA Astrophysics Data System (ADS)

Plechaty, Christopher; Sotnikov, Vladimir; Main, Daniel; Caplinger, James; Wallerstein, Austin; Kim, Tony

2014-10-01

The Lower Hybrid Drift Instability (LHDI) in plasma is driven by the presence of inhomogeneities in density, temperature, or magnetic field (Krall 1971, Davidson 1977), and occurs in systems where the electrons are magnetized and the ions are effectively unmagnetized. The LHDI is thought to occur in magnetic reconnection (Huba 1977), and has also been investigated as a mitigation technique which can allow for communications to take place through the plasma formed around hypersonic aircraft (Sotnikov 2010). To further understand the phenomenology of the LHDI, we plan to carry out experiments at the Air Force Research Laboratory, in the newly formed Plasma Physics Sensors Laboratory. In experiment, a pulsed power generator is employed to produce plasma by passing current through single, or dual-wire configurations. To characterize the plasma, a Thomson scattering diagnostic is employed, along with a visible spectroscopy diagnostic. This work was performed under the auspices of the U.S. Department of Defense by Riverside Research under Contract BAA-FA8650-13-C-1539.

Numerical simulation of fiber and wire array Z-pinches with Trac-II

NASA Astrophysics Data System (ADS)

Reisman, David Barton

Trac-II is a two dimensional axisymmetric resistive MHD code. It simulates all three spatial components (r, z, φ) of the magnetic field and fluid velocity vectors, and the plasma is treated as a single fluid with two temperatures (Te,Ti). In addition, it can optionally include a self-consistent external circuit. Recent modifications to the code include the addition of the 3-T radiation model, a 4-phase (solid- liquid-vapor-plasma) equation of state model (QEOS), a 4- phase electrical/thermal conductivity model, and an implicit solution of poloidal (Bz,Br) magnetic field diffusion. These changes permit a detailed study of fiber and wire array Z-pinches. Specifically, Trac-II is used to study the wire array Z-pinch at the PBFA-Z pulse power generator at Sandia National Laboratory. First, in 1-D we examine the behavior of a single wire in the Z-pinch. Then, using these results as initial radial conditions in 2-D, we investigate the dynamics of wire array configurations in the r-z and r-θ plane. In the r- z plane we examine the growth of the m = 0 or ``sausage'' instability in single wires within the array. In the r-θ plane we examine the merging behavior between neighboring wires. Special emphasis is placed on trying to explain how instability growth affects the performance of the Z-pinch. Lastly, we introduce Trac-III, a 3-D MHD code, and illustrate the m = 1 or ``kink'' instability. We also discuss how Trac-III can be modified to simulate the wire array Z-pinch.

50th Annual Fuze Conference Sessions 3 and 4 Held in Norfolk, Virginia on May 9-11, 2006

DTIC Science & Technology

2006-05-11

Exploding Foil Initiator Research • Research on Explosives • Conclusion Wim Prinse Research Scientist3 TNO has organised...Research Scientist6 Exploding Foil Initiator Research • Electrical circuit • Exploding foil • Velocity of the flyer • Driver Explosive • Secondary...90% efficiency of energy deposited in the exploding foil (50 % other circuits) Wim Prinse Research Scientist8 Exploding foil • Dimension of the foil

Feasibility study of silicon nitride protection of plastic encapsulated semiconductors

NASA Technical Reports Server (NTRS)

Peters, J. W.; Hall, T. C.; Erickson, J. J.; Gebhart, F. L.

1979-01-01

The application of low temperature silicon nitride protective layers on wire bonded integrated circuits mounted on lead frame assemblies is reported. An evaluation of the mechanical and electrical compatibility of both plasma nitride and photochemical silicon nitride (photonitride) passivations (parallel evaluations) of integrated circuits which were then encapsulated in plastic is described. Photonitride passivation is compatible with all wire bonded lead frame assemblies, with or without initial chip passivation. Plasma nitride passivation of lead frame assemblies is possible only if the chip is passivated before lead frame assembly. The survival rate after the environmental test sequence of devices with a coating of plasma nitride on the chip and a coating of either plasma nitride or photonitride over the assembled device is significantly greater than that of devices assembled with no nitride protective coating over either chip or lead frame.

Generation of fast protons by interaction of modest laser intensities with H2O “snow” nano-wire targets

NASA Astrophysics Data System (ADS)

Bruner, Nir; Schleifer, Elad; Palchan, Tala; Pikuz, Sergey A.; Eisenmann, Shmuel; Botton, Mordechai; Gordon, Dan; Zigler, Arie

2011-10-01

We report on the generation of protons with energies of 5.5 MeV when irradiating an H 2O nano-wire layer grown on a sapphire plate with an intensity of 5×10 17 W/cm 2. A theoretical model is suggested in which plasma near the tip of the wire is subject to enhanced electrical fields and protons are accelerated to several MeVs.

[Plasma temperature calculation and coupling mechanism analysis of laser-double wire hybrid welding].

PubMed

Zheng, Kai; Li, Huan; Yang, Li-Jun; Gu, Xiao-Yan; Gao, Ying

2013-04-01

The plasma radiation of laser-double wire hybrid welding was collected by using fiber spectrometer, the coupling mechanism of arc with laser was studied through high-speed photography during welding process, and the temperature of hybrid plasma was calculated by using the method of Boltzmann plot. The results indicated that with laser hybrid, luminance was enhanced; radiation intensity became stronger; arc was attracted to the laser point; cross section contracted and arc was more stable. The laser power, welding current and arc-arc distance are important factors that have great influence on electron temperature. Increase in the laser power, amplification of welding current and reduction of arc-arc distance can all result in the rise of temperature.

Current redistribution and generation of kinetic energy in the stagnated Z pinch.

PubMed

Ivanov, V V; Anderson, A A; Papp, D; Astanovitskiy, A L; Talbot, B R; Chittenden, J P; Niasse, N

2013-07-01

The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%.

Heating in short-pulse laser-driven cone-capped wire targets

NASA Astrophysics Data System (ADS)

Mason, R. J.; Wei, M.; King, J.; Beg, F.; Stephens, R. B.

2007-11-01

The 2-D implicit hybrid simulation code e-PLAS has been used to study heating in cone-capped copper wire targets. The code e-PLAS tracks collisional particle-in-cell (PIC) electrons traversing background plasma of collisional Eulerian cold electron and ion fluids. It computes E- and B-fields by the Implicit Moment Method [1,2]. In recent experiments [3] at the Vulcan laser facility, sub- picosecond laser pulses at 1.06 μm, and 4.0 x 10^20 W/cm^2 intensity were focused into thin-walled (˜10 μm) cones attached to copper wires. The wire diameter was varied from 10-40 μm with a typical length of 1 mm. We characterize heating of the wires as a function of their diameters and length, and relate modifications of this heating to changes in the assumed laser-generated hot electron spectrum and directivity. As in recent nail experiments [4], the cones can serve as reservoirs for hot electrons, diverting them from passage down the wires. [1] R. J. Mason, and C. Cranfill, IEEE Trans. Plasma Sci. PS-14, 45 (1986). [2] R. J. Mason, J. Comp. Phys. 71, 429 (1987). [3] J. King et al., to be submitted to Phys. Rev. Lett.. [4] R. J. Mason, M. Wei, F. Beg, R. Stephens, and C. Snell, in Proc. of ICOPS07, Albuquerque, NM, June 17-22, 2007, Talk 7D4.

Study of the effect of collisionality and cooling on the interactions of counter-streaming plasma flows as a function of wire material

NASA Astrophysics Data System (ADS)

Collins, Gilbert; Valenzuela, Julio; Aybar, Nicholas; Conti, Fabio; Beg, Farhat

2017-10-01

We report on the effects wire material on collisionality and radiative cooling on the interactions of counter-streaming plasma jets produced by conical wire arrays on the 200 kA GenASIS driver. In these interactions, mean free path (λmfp) scales with jet velocity (vjet4),atomic mass (A2), and ionization (Z*-4), while cooling scales with atomic mass. By changing the material of the jets one can create slowly cooling, weakly collisional regimes using C, Al, or Cu, or strongly cooled, effectively collisionless plasmas using Mo or W. The former produced smooth shocks soon after the jets collide (near the peak current of 150 ns) that grew in size over time. Interactions of the latter produced multiple structures of a different shape, at a later time ( 300 ns) that dissipated rapidly compared to the lower Z materials. We will report on the scaleability of these different materials to astrophysical phenomena. This work was partially supported by the Department of Energy Grant Number DE-SC0014493.

Dynamics of vapor emissions at wire explosion thresholda)

NASA Astrophysics Data System (ADS)

Belony, Paul A.; Kim, Yong W.

2010-10-01

X-pinch plasmas have been actively studied in the recent years. Numerical simulation of the ramp-up of metallic vapor emissions from wire specimens shows that under impulsive Ohmic heating the wire core invariably reaches a supercritical state before explosion. The heating rate depends sensitively on the local wire resistance, leading to highly variable vapor emission flux along the wire. To examine the vapor emission process, we have visualized nickel wire explosions by means of shock formation in air. In a single explosion as captured by shadowgraphy, there usually appear several shocks with spherical or cylindrical wave front originating from different parts of the wire. Growth of various shock fronts in time is well characterized by a power-law scaling in one form or another. Continuum emission spectra are obtained and calibrated to measure temperature near the explosion threshold. Shock front structures and vapor plume temperature are examined.

Influence of insulating coating on aluminum wire explosions

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

Li, Yang; Wu, Jian, E-mail: jxjawj@gmail.com; State Key Laboratory of Intense Pulse Radiation of Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024

2014-10-15

Single wire explosions are widely used in understanding the early stages of z-pinch experiments. This paper presents a serial of experiments conducted on the pulse power generator with ∼1 kA peak current and ∼10 ns rising time in Xi'an Jiao Tong University. Polyimide coated aluminum wires and uncoated ones were tested under three different voltages to analyze the effect of insulating coating. Experimental results showed that insulating coating can increase the energy deposition 10%∼30% in aluminum wires by delaying the voltage collapse and raising the maximum load resistance. The substantial energy deposition resulted in about 20% faster expansion rates for coated wires.more » Experimental evidence that plasma channel shunts the current from the wire core was observed by streak camera and schlieren graphs. This paper also briefly discussed the influence of nonuniform coating on the morphology of wire expansion.« less

Study on factors affecting the droplet temperature in plasma MIG welding process

NASA Astrophysics Data System (ADS)

Mamat, Sarizam Bin; Tashiro, Shinichi; Tanaka, Manabu; Yusoff, Mahani

2018-04-01

In the present study, the mechanism to control droplet temperature in the plasma MIG welding was discussed based on the measurements of the droplet temperature for a wide range of MIG currents with different plasma electrode diameters. The measurements of the droplet temperatures were conducted using a two color temperature measurement method. The droplet temperatures in the plasma MIG welding were then compared with those in the conventional MIG welding. As a result, the droplet temperature in the plasma MIG welding was found to be reduced in comparison with the conventional MIG welding under the same MIG current. Especially when the small plasma electrode diameter was used, the decrease in the droplet temperature reached maximally 500 K. Also, for a particular WFS, the droplet temperatures in the plasma MIG welding were lower than those in the conventional MIG welding. It is suggested that the use of plasma contributes to reducing the local heat input into the base metal by the droplet. The presence of the plasma surrounding the wire is considered to increase the electron density in its vicinity, resulting in the arc attachment expanding upwards along the wire surface to disperse the MIG current. This dispersion of MIG current causes a decrease in current density on the droplet surface, lowering the droplet temperature. Furthermore, dispersed MIG current also weakens the electromagnetic pinch force acting on the neck of the wire above the droplet. This leads to a larger droplet diameter with increased surface area through lower frequency of droplet detachment to decrease the MIG current density on the droplet surface, as compared to the conventional MIG welding at the same MIG current. Thus, the lower droplet temperature is caused by the reduction of heat flux into the droplet. Consequently, the mechanism to control droplet temperature in the plasma MIG welding was clarified.

Apparatus For Metal/Inert-Gas Welding In Vacuum

NASA Technical Reports Server (NTRS)

Stocks, C. O.

1994-01-01

Metal/inert-gas welding-torch assembly operates in vacuum. Plasma generated in interior chamber and focused onto workpiece in vacuum. Pinch rollers feed wire to weld puddle. Controlled flow of plasma reduces dispersal in vacuum, preventing extinction.

Electric Discharge Sintering and Joining of Tungsten Carbide—Cobalt Composite with High-Speed Steel Substrate

NASA Astrophysics Data System (ADS)

Grigoryev, Evgeny G.

2011-01-01

Simultaneous electro discharge sintering of high strength structure of tungsten carbide—cobalt composite and connection it with high-speed steel substrate is investigated and suitable operating parameters are defined. Tungsten carbide—cobalt and high-speed steel joining was produced by the method of high voltage electrical discharge together with application of mechanical pressure to powder compact. It was found that the density and hardness of composite material reach its maximum values at certain magnitudes of applied pressure and high voltage electrical discharge parameters. We show that there is an upper level for the discharge voltage beyond which the powder of composite material disintegrates like an exploding wire. Due to our results it is possible to determine optimal parameters for simultaneous electro discharge sintering of WC-Co and bonding it with high-speed steel substrate.

250 kA compact linear transformer driver for wire array z-pinch loads

NASA Astrophysics Data System (ADS)

Bott, S. C.; Haas, D. M.; Madden, R. E.; Ueda, U.; Eshaq, Y.; Collins, G., IV; Gunasekera, K.; Mariscal, D.; Peebles, J.; Beg, F. N.; Mazarakis, M.; Struve, K.; Sharpe, R.

2011-05-01

We present the application of a short rise (˜150ns) 250 kA linear transformer driver (LTD) to wire array z-pinch loads for the first time. The generator is a modification of a previous driver in which a new conical power feed provides a low inductance coupling to wire loads. Performance of the new design using both short circuit and plasma loads is presented and discussed. The final design delivers ˜200kA to a wire array load which is in good agreement with SCREAMER calculations using a simplified representative circuit. Example results demonstrate successful experiments using cylindrical, conical, and inverse wire arrays as well as previously published work on x-pinch loads.

Observation of fast expansion velocity with insulating tungsten wires on ∼80 kA facility

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

Li, M.; Li, Y.; State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024

2016-07-15

This paper presents experimental results on the effects of insulating coatings on tungsten planar wire array Z-pinches on an 80 kA, 100 ns current facility. Expansion velocity is obviously increased from ∼0.25 km/s to ∼3.5 km/s by using the insulating coatings. It can be inferred that the wire cores are in gaseous state with this fast expansion velocity. An optical framing camera and laser probing images show that the standard wire arrays have typical ablation process which is similar to their behaviors on mega-ampere facilities. The ablation process and precursor plasma are suppressed for dielectric tungsten wires. The wire array implosion might be improvedmore » if these phenomena can be reproduced on Mega-ampere facilities.« less

Laser-heated emissive plasma probe.

PubMed

Schrittwieser, Roman; Ionita, Codrina; Balan, Petru; Gstrein, Ramona; Grulke, Olaf; Windisch, Thomas; Brandt, Christian; Klinger, Thomas; Madani, Ramin; Amarandei, George; Sarma, Arun K

2008-08-01

Emissive probes are standard tools in laboratory plasmas for the direct determination of the plasma potential. Usually they consist of a loop of refractory wire heated by an electric current until sufficient electron emission. Recently emissive probes were used also for measuring the radial fluctuation-induced particle flux and other essential parameters of edge turbulence in magnetized toroidal hot plasmas [R. Schrittwieser et al., Plasma Phys. Controlled Fusion 50, 055004 (2008)]. We have developed and investigated various types of emissive probes, which were heated by a focused infrared laser beam. Such a probe has several advantages: higher probe temperature without evaporation or melting and thus higher emissivity and longer lifetime, no deformation of the probe in a magnetic field, no potential drop along the probe wire, and faster time response. The probes are heated by an infrared diode laser with 808 nm wavelength and an output power up to 50 W. One probe was mounted together with the lens system on a radially movable probe shaft, and radial profiles of the plasma potential and of its oscillations were measured in a linear helicon discharge.

The effects of return current and target charging in short pulse high intensity laser interactions

NASA Astrophysics Data System (ADS)

Beg, Farhat

2003-10-01

Since the introduction of the technique of chirped pulse amplification (CPA), peak laser intensities have increased dramatically. It is now possible to perform laser-plasma interaction experiments at intensities approaching 1021 Wcm-2. The electrons in the field of such lasers are highly relativistic (gamma 31) and the temperature of the hot electron distribution produced in a plasma at such extreme intensities can exceed 10 MeV. Since the resulting beam current exceeds the Alfvén limit, a neutralizing return current of cold plasma electrons moving in the opposite direction is produced. Another source of return current is that due to the escape of very energetic electrons from the target, which then creates a large electrostatic potential due to charge separation. These return currents can cause significant ohmic heating. We present results from experiments performed at Rutherford Appleton Laboratory using the VULCAN laser facility (I> 5 x1019 Wcm-2). Single wire targets were used and in some shots a secondary wire or foil was placed near the target. Three main observations were made: (i) generation of a Z-pinch in the wire due to the return current, (ii) optical transition radiation at 2w and (iii) proton emission from both the primary wire target and the secondary wire or foil. The Z-pinch was observed to be m=0 unstable. The current was estimated to be about 0.8 MA using simple energy balance considerations. Intense second harmonic emission due to coherent optical transition radiation from both the primary target and secondary objects was observed and is likely due to electron bunches accelerated by the ponderomotive jxB force of the laser. The proton emission from the secondary wire or foil was likely due to field emission of electrons from the these objects in response to the large potential produced from charging of the primary target. Results of simulations to model these interactions will also be presented.

Atomic oxygen behavior at downstream of AC excited atmospheric pressure He plasma jet

NASA Astrophysics Data System (ADS)

Takeda, Keigo; Ishikawa, Kenji; Tanaka, Hiromasa; Sekine, Makoto; Hori, Masaru

2016-09-01

Applications of atmospheric pressure plasma jets (APPJ) have been investigated in the plasma medical fields such as cancer therapy, blood coagulation, etc. Reactive species generated by the plasma jet interacts with the biological surface. Therefore, the issue attracts much attentions to investigate the plasma effects on targets. In our group, a spot-size AC excited He APPJ have been used for the plasma medicine. From diagnostics of the APPJ using optical emission spectroscopy, the gas temperature and the electron density was estimated to be 299 K and 3.4 ×1015 cm-3. The AC excited He APPJ which affords high density plasma at room temperature is considered to be a powerful tool for the medical applications. In this study, by using vacuum ultraviolet absorption spectroscopy, the density of atomic oxygen on a floating copper as a target irradiated by the He APPJ was measured as a function of the distance between the plasma source and the copper wire. The measured density became a maximum value around 8 ×1013 cm-3 at 12 mm distance, and then decreased over the distance. It is considered that the behavior was due to the changes in the plasma density on the copper wire and influence of ambient air.

Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

NASA Astrophysics Data System (ADS)

Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

2014-01-01

Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

Method for making generally cylindrical underground openings

DOEpatents

Routh, J.W.

1983-05-26

A rapid, economical and safe method for making a generally cylindrical underground opening such as a shaft or a tunnel is described. A borehole is formed along the approximate center line of where it is desired to make the underground opening. The borehole is loaded with an explodable material and the explodable material is detonated. An enlarged cavity is formed by the explosive action of the detonated explodable material forcing outward and compacting the original walls of the borehole. The enlarged cavity may be increased in size by loading it with a second explodable material, and detonating the second explodable material. The process may be repeated as required until the desired underground opening is made. The explodable material used in the method may be free-flowing, and it may be contained in a pipe.

[Arc spectrum diagnostic and heat coupling mechanism analysis of double wire pulsed MIG welding].

PubMed

Liu, Yong-qiang; Li, Huan; Yang, Li-jun; Zheng, Kai; Gao, Ying

2015-01-01

A double wire pulsed MIG welding test system was built in the present paper, in order to analyze the heat-coupling mechanism of double wire pulsed MIG welding, and study are temperature field. Spectroscopic technique was used in diagnostic analysis of the are, plasma radiation was collected by using hollow probe method to obtain the arc plasma optical signal The electron temperature of double wire pulsed MIG welding arc plasma was calculated by using Boltzmann diagram method, the electron temperature distribution was obtained, a comprehensive analysis of the arc was conducted combined with the high speed camera technology and acquisition means of electricity signal. The innovation of this paper is the combination of high-speed camera image information of are and optical signal of arc plasma to analyze the coupling mechanism for dual arc, and a more intuitive analysis for are temperature field was conducted. The test results showed that a push-pull output was achieved and droplet transfer mode was a drop in a pulse in the welding process; Two arcs attracted each other under the action of a magnetic field, and shifted to the center of the arc in welding process, so a new heat center was formed at the geometric center of the double arc, and flowing up phenomenon occurred on the arc; Dual arc electronic temperature showed an inverted V-shaped distribution overall, and at the geometric center of the double arc, the arc electron temperature at 3 mm off the workpiece surface was the highest, which was 16,887.66 K, about 4,900 K higher than the lowest temperature 11,963.63 K.

The many sides of RCW 86: a Type Ia supernova remnant evolving in its progenitor's wind bubble

NASA Astrophysics Data System (ADS)

Broersen, Sjors; Chiotellis, Alexandros; Vink, Jacco; Bamba, Aya

2014-07-01

We present the results of a detailed investigation of the Galactic supernova remnant RCW 86 using the XMM-Newton X-ray telescope. RCW 86 is the probable remnant of SN 185 A.D., a supernova that likely exploded inside a wind-blown cavity. We use the XMM-Newton Reflection Grating Spectrometer to derive precise temperatures and ionization ages of the plasma, which are an indication of the interaction history of the remnant with the presumed cavity. We find that the spectra are well fitted by two non-equilibrium ionization models, which enables us to constrain the properties of the ejecta and interstellar matter plasma. Furthermore, we performed a principal component analysis on EPIC MOS and pn data to find regions with particular spectral properties. We present evidence that the shocked ejecta, emitting Fe K and Si line emission, are confined to a shell of approximately 2 pc width with an oblate spheroidal morphology. Using detailed hydrodynamical simulations, we show that general dynamical and emission properties at different portions of the remnant can be well reproduced by a Type Ia supernova that exploded in a non-spherically symmetric wind-blown cavity. We also show that this cavity can be created using general wind properties for a single degenerate system. Our data and simulations provide further evidence that RCW 86 is indeed the remnant of SN 185, and is the likely result of a Type Ia explosion of single degenerate origin.

Linear and nonlinear evolution of azimuthal clumping instabilities in a Z-pinch wire array

DOE PAGES

Tang, Wilkin; Strickler, T. S.; Lau, Y. Y.; ...

2007-01-31

This study presents an analytic theory on the linear and nonlinear evolution of the most unstable azimuthal clumping mode, known as the pi-mode, in a discrete wire array. In the pi-mode, neighboring wires of the array pair-up as a result of the mutual attraction of the wires which carry current in the same direction. The analytic solution displays two regimes, where the collective interactions of all wires dominate, versus where the interaction of the neighboring, single wire dominates. This solution was corroborated by two vastly different numerical codes which were used to simulate arrays with both high wire numbers (upmore » to 600) and low wire number (8). All solutions show that azimuthal clumping of discrete wires occurs before appreciable radial motion of the wires. Thus, absence of azimuthal clumping of wires in comparison with the wires’ radial motion may imply substantial lack of wire currents. Finally, while the present theory and simulations have ignored the plasma corona and axial variations, it is argued that their effects, and the complete account of the three-dimensional feature of the pi-mode, together with a scaling study of the wire number, may be expediently simulated by using only one single wire in an annular wedge with a reflection condition imposed on the wedge’s boundary.« less

Multi-gap high impedance plasma opening switch

DOEpatents

Mason, Rodney J.

1996-01-01

A high impedance plasma opening switch having an anode and a cathode and at least one additional electrode placed between the anode and cathode. The presence of the additional electrodes leads to the creation of additional plasma gaps which are in series, increasing the net impedance of the switch. An equivalent effect can be obtained by using two or more conventional plasma switches with their plasma gaps wired in series. Higher impedance switches can provide high current and voltage to higher impedance loads such as plasma radiation sources.

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

Yamaguchi, Hiroya; Badenes, Carles; Foster, Adam R.

Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only bemore » achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Altogether with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.« less

Synchrotron emission from nanowire array targets irradiated by ultraintense laser pulses

NASA Astrophysics Data System (ADS)

Martinez, B.; d’Humières, E.; Gremillet, L.

2018-07-01

We present a numerical study, based on two-dimensional particle-in-cell simulations, of the synchrotron emission induced during the interaction of femtosecond laser pulses of intensities I = 1021–1023 W cm‑2 with nanowire arrays. Through an extensive parametric scan on the target parameters, we identify and characterize several dominant radiation mechanisms, mainly depending on the transparency or opacity of the plasma produced by the wire expansion. At I = 1022 W m‑2, the emission of high-energy (>10 keV) photons attains a maximum conversion efficiency of ∼10% for 36–50 nm wire widths and 1 μm interspacing. This maximum radiation yield is found to be similar to that achieved in a uniform plasma of same average (sub-solid) density, but nanowire arrays provide efficient radiation sources over a broader parameter range. Moreover, we examine the variations of the photon spectra with the laser intensity and the wire material, and we demonstrate that the radiation efficiency can be further enhanced by adding a plasma mirror at the backside of the nanowire array. Finally, we briefly consider the influence of a finite laser focal spot and oblique incidence angle.

Large Volume Non-Equilibrium Air Plasma at Atmospheric Pressure: A Novel Method with Low Power Requirements

DTIC Science & Technology

2007-02-28

of magnitude in size. Also unlike corona -like devices such as the plasma needle , which generates 2-3 mm long plasma at the tip of a sharp wire...Distribution Unlimited Table of Contents Abstract AC System with Water Electrode Current voltage characteristics Plasma diagnostics results Experimental setup...Laroussi, PI. 4 AC SYSTEM WITH WATER ELECTRODE Recently, non-equilibrium atmospheric pressure plasmas have been used in a variety of material processing

Compression dynamics of quasi-spherical wire arrays with different linear mass profiles

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

Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Aleksandrov, V. V.; Gritsuk, A. N.

Results of experimental studies of the implosion of quasi-spherical wire (or metalized fiber) arrays are presented. The goal of the experiments was to achieve synchronous three-dimensional compression of the plasma produced in different regions of a quasi-spherical array into its geometrical center. To search for optimal synchronization conditions, quasi-spherical arrays with different initial profiles of the linear mass were used. The following dependences of the linear mass on the poloidal angle were used: m{sub l}(θ) ∝ sin{sup –1}θ and m{sub l}(θ) ∝ sin{sup –2}θ. The compression dynamics of such arrays was compared with that of quasi-spherical arrays without linear massmore » profiling, m{sub l}(θ) = const. To verify the experimental data, the spatiotemporal dynamics of plasma compression in quasi-spherical arrays was studied using various diagnostics. The experiments on three-dimensional implosion of quasi-spherical arrays made it possible to study how the frozen-in magnetic field of the discharge current penetrates into the array. By measuring the magnetic field in the plasma of a quasi-spherical array, information is obtained on the processes of plasma production and formation of plasma flows from the wire/fiber regions with and without an additionally deposited mass. It is found that penetration of the magnetic flux depends on the initial linear mass profile m{sub l}(θ) of the quasi-spherical array. From space-resolved spectral measurements and frame imaging of plasma X-ray emission, information is obtained on the dimensions and shape of the X-ray source formed during the implosion of a quasi-spherical array. The intensity of this source is estimated and compared with that of the Z-pinch formed during the implosion of a cylindrical array.« less

The quantum pinch effect in semiconducting quantum wires: A bird’s-eye view

NASA Astrophysics Data System (ADS)

Kushwaha, Manvir S.

2016-01-01

Those who measure success with culmination do not seem to be aware that life is a journey not a destination. This spirit is best reflected in the unceasing failures in efforts for solving the problem of controlled thermonuclear fusion for even the simplest pinches for over decades; and the nature keeps us challenging with examples. However, these efforts have permitted researchers the obtention of a dense plasma with a lifetime that, albeit short, is sufficient to study the physics of the pinch effect, to create methods of plasma diagnostics, and to develop a modern theory of plasma processes. Most importantly, they have impregnated the solid state plasmas, particularly the electron-hole plasmas in semiconductors, which do not suffer from the issues related with the confinement and which have demonstrated their potential not only for the fundamental physics but also for the device physics. Here, we report on a two-component, cylindrical, quasi-one-dimensional quantum plasma subjected to a radial confining harmonic potential and an applied magnetic field in the symmetric gauge. It is demonstrated that such a system, as can be realized in semiconducting quantum wires, offers an excellent medium for observing the quantum pinch effect at low temperatures. An exact analytical solution of the problem allows us to make significant observations: Surprisingly, in contrast to the classical pinch effect, the particle density as well as the current density display a determinable maximum before attaining a minimum at the surface of the quantum wire. The effect will persist as long as the equilibrium pair density is sustained. Therefore, the technological promise that emerges is the route to the precise electronic devices that will control the particle beams at the nanoscale.

Emission of energetic protons from relativistic intensity laser interaction with a cone-wire target.

PubMed

Paradkar, B S; Yabuuchi, T; Sawada, H; Higginson, D P; Link, A; Wei, M S; Stephens, R B; Krasheninnikov, S I; Beg, F N

2012-11-01

Emission of energetic protons (maximum energy ∼18 MeV) from the interaction of relativistic intensity laser with a cone-wire target is experimentally measured and numerically simulated with hybrid particle-in-cell code, lsp [D. R. Welch et al., Phys. Plasmas 13, 063105 (2006)]. The protons originate from the wire attached to the cone after the OMEGA EP laser (670 J, 10 ps, 5 × 10^{18} W/cm^{2}) deposits its energy inside the cone. These protons are accelerated from the contaminant layer on the wire surface, and are measured in the radial direction, i.e., in a direction transverse to the wire length. Simulations show that the radial electric field, responsible for the proton acceleration, is excited by three factors, viz., (i) transverse momentum of the relativistic fast electrons beam entering into the wire, (ii) scattering of electrons inside the wire, and (iii) refluxing of escaped electrons by "fountain effect" at the end of the wire. The underlying physics of radial electric field and acceleration of protons is discussed.

X-ray source characterization of aluminum X-pinch plasmas driven by the 0. 5 TW LION accelerator

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

Qi, N.; Hammer, D.A.; Kalantar, D.H.

1989-12-01

Recent experiments at Cornell have been performed to investigate X-pinch plasmas as intense x-ray sources which might be used to pump resonant photoexcitation lasers. Crossed Al wires have been driven by up to 600 kA current for 40 ns. High density bright spots are observed at the crossing point(s). Various diagnostics were used to characterize the X-pinch plasmas as a function of initial mass loading for several specific wire configurations. The optimum mass loading for different ionization stages of Al, and the total x-ray energy yields, which are on the order of hundreds of Joules, were examined. Estimates of plasmamore » density, {similar to}10{sup 20} cm{sup {minus}3}, and temperature, about 400 eV, were obtained.« less

Strategy to Minimize Energetics Contamination at Military Testing/Training Ranges

DTIC Science & Technology

2005-09-01

exploding foil exploding foil initiator ) initiator will minimize the energetic material...i.e., exploding foil initiator P 𔃾 𔃾 𔃾 𔃾 4. Use an electronic S&A; i.e., high voltage driven semi-conductor bridge elements P ’ 𔃾 𔃾 𔃾 5. Use...alternatives Opportunity 1. Eliminate energetics 3. Use an electronic S&A; i.e., exploding foil initiator 1 3 3 -3 2 -6 -2 1 -2 -5 4. Use an

Use of Plasma Actuators as a Moving-Wake Generator

NASA Technical Reports Server (NTRS)

Corke, Thomas C.; Thomas, Flint O.; Klapetzky Michael J.

2007-01-01

The work documented in this report tests the concept of using plasma actuators as a simple and easy way to generate a simulated moving-wake and the disturbances associated with it in turbines. This wake is caused by the blades of the upstream stages of the turbine. Two types of devices, one constructed of arrays of NACA 0018 airfoils, and the one constructed of flat plates were studied. The airfoils or plates were equipped with surface mounted dielectric barrier discharge (DBD) plasma actuators, which were used to generate flow disturbances resembling moving-wakes. CTA hot-wire anemometry and flow visualization using a smoke-wire were used to investigate the wake independence at various spacings and downstream locations. The flat plates were found to produce better results than the airfoils in creating large velocity fluctuations in the free-stream flow. Different dielectric materials, plasma actuator locations, leading edge contours, angles of attack and plate spacings were investigated, some with positive results. The magnitudes of the velocity fluctuations were found to be comparable to existing mechanical moving-wake generators, thus proving the feasibility of using plasma actuators as a moving-wake generator.

Primary experimental results of wire-array Z-pinches on PTS

NASA Astrophysics Data System (ADS)

Huang, X. B.; Zhou, S. T.; Ren, X. D.; Dan, J. K.; Wang, K. L.; Zhang, S. Q.; Li, J.; Xu, Q.; Cai, H. C.; Duan, S. C.; Ouyang, K.; Chen, G. H.; Ji, C.; Wang, M.; Feng, S. P.; Yang, L. B.; Xie, W. P.; Deng, J. J.

2014-12-01

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a multiterawatt pulsed power driver, which can deliver a ˜10 MA, 70 ns rise-time (10%-90%) current to a short circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. In this paper, primary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 14.4-26.4 mm, and consisting of 132˜276 tungsten wires with 5˜10 μm in diameter. Multiple diagnostics were fielded to determine the characteristics of x-ray radiations and to obtain self-emitting images of imploding plasmas. X-ray power up to 80 TW with ˜3 ns FWMH is achieved by using nested wire arrays. The total x-ray energy exceeds 500 kJ and the peak radiation temperature is about 150 eV. Typical velocity of imploding plasmas goes around 3˜5×107 cm/s and the radial convergence ratio is between 10 and 20.

Simulation of detonation cell kinematics using two-dimensional reactive blast waves

NASA Astrophysics Data System (ADS)

Thomas, G. O.; Edwards, D. H.

1983-10-01

A method of generating a cylindrical blast wave is developed which overcomes the disadvantages inherent in the converging-diverging nozzle technique used by Edwards et al., 1981. It is demonstrated than an exploding wire placed at the apex of a two-dimensional sector provides a satisfactory source of the generation of blast waves in reactive systems. The velocity profiles of the blast waves are found to simulate those in freely propagating detonations very well, and this method does not suffer from the disadvantage of having the mass flow at the throat as in the nozzle method. The density decay parameter is determined to have a constant value of 4 in the systems investigated, and it is suggested that this may be a universal value. It is proposed that suitable wedges could be used to create artificial Mach stems in the same manner as Strehlow and Barthel (1971) without the attendant disadvantages of the nozzle method.

Influence of low energy argon plasma treatment on the moisture barrier performance of hot wire-CVD grown SiNx multilayers

NASA Astrophysics Data System (ADS)

Majee, Subimal; Fátima Cerqueira, Maria; Tondelier, Denis; Geffroy, Bernard; Bonnassieux, Yvan; Alpuim, Pedro; Bourée, Jean Eric

2014-01-01

The reliability and stability are key issues for the commercial utilization of organic photovoltaic devices based on flexible polymer substrates. To increase the shelf-lifetime of these devices, transparent moisture barriers of silicon nitride (SiNx) films are deposited at low temperature by hot wire CVD (HW-CVD) process. Instead of the conventional route based on organic/inorganic hybrid structures, this work defines a new route consisting in depositing multilayer stacks of SiNx thin films, each single layer being treated by argon plasma. The plasma treatment allows creating smoother surface and surface atom rearrangement. We define a critical thickness of the single layer film and focus our attention on the effect of increasing the number of SiNx single-layers on the barrier properties. A water vapor transmission rate (WVTR) of 2 × 10-4 g/(m2·day) is reported for SiNx multilayer stack and a physical interpretation of the plasma treatment effect is given.

Analysis of the effects of atomic mass, jet velocity, and radiative cooling on the dimensionless parameters of counter-propagating, weakly collisional plasma flows

NASA Astrophysics Data System (ADS)

Collins, Gilbert; Valenzuela, Julio; Beg, Farhat

2016-10-01

We have studied the collision of counter-propagating plasma flows using opposing conical wire arrays driven by the 200kA, 150ns rise-time `GenASIS' driver. These plasma flows produced weakly collisional, well-defined bow-shock structures. Varying initial parameters such as the opening angle of the array and the atomic mass of the wires allowed us to modify quantities such as the density contrast between jets, intra-jet mean free path (λmfp, scales with v, atomic mass A, and ionization state Zi-4) , Reynolds number (Re, scales with AZ), and the Peclet number (Pe, scales with Z). We calculate these dimensionless quantities using schlieren imagery, interferometry, and emission data, and determine whether they meet the scaling criteria necessary for the comparison to and subsequent study of astrophysical plasmas. This work was partially supported by the Department of Energy Grant Number DE-SC0014493.

Left-handed transmission in a simple cut-wire pair structure

NASA Astrophysics Data System (ADS)

Tung, Nguyen Thanh; Thuy, Vu Tran Thanh; Park, Jin Woo; Rhee, Joo Yull; Lee, YoungPak

2010-01-01

It is well known that, together with the plasma behavior of continuous wires, the use of cut-wire pair as a metamagnetic component is to drive the negative permeability in the left-handed combined structure. In this study, we have investigated a strange left-handed transmission in a metamaterial consisting of only conventional cut-wire pair structure without additional adjustment. It is shown that the observed left-handed behavior, which occurs at a frequency three times higher than that for the combined structure, originates from the fundamental negative permittivity provided by the symmetric resonant mode and a negative permeability by the third-order asymmetric resonance. Our results would simplify extremely the fabricating procedure, especially, for terahertz regime as well as reveal many possibilities to design optical devices based on the electromagnetic responses of cut-wire structure.

Development of a PDXP platform on NIF

NASA Astrophysics Data System (ADS)

Whitley, Heather; Schneider, Marilyn; Garbett, Warren; Pino, Jesse; Shepherd, Ronnie; Brown, Colin; Castor, John; Scott, Howard; Ellison, C. Leland; Benedict, Lorin; Sio, Hong; Lahmann, Brandon; Petrasso, Richard; Graziani, Frank

2016-10-01

Over the past several years, we have conducted theoretical investigations of electron-ion coupling and electronic transport in plasmas. In the regime of weakly coupled plasmas, we have identified models that we believe describe the physics well, but experimental measurements are still needed to validate the models. We are developing spectroscopic experiments to study electron-ion equilibration and electron heat transport using a polar direct drive exploding pusher (PDXP) platform at the National Ignition Facility (NIF). Initial measurements are focused on characterizing the laser-target coupling, symmetry of the PDXP implosion, and overall neutron and x-ray signals. We present images from the first set of shots and make comparisons with simulations from ARES and discuss next steps in the platform development. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-697489.

Multi-gap high impedance plasma opening switch

DOEpatents

Mason, R.J.

1996-10-22

A high impedance plasma opening switch having an anode and a cathode and at least one additional electrode placed between the anode and cathode is disclosed. The presence of the additional electrodes leads to the creation of additional plasma gaps which are in series, increasing the net impedance of the switch. An equivalent effect can be obtained by using two or more conventional plasma switches with their plasma gaps wired in series. Higher impedance switches can provide high current and voltage to higher impedance loads such as plasma radiation sources. 12 figs.

Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays

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

Aleksandrov, V. V., E-mail: alexvv@triniti.ru; Gasilov, V. A.; Grabovski, E. V.

Results are presented from experimental studies of the characteristics of the soft X-ray (SXR) source formed in the implosion of quasi-spherical arrays made of tungsten wires and metalized kapron fibers. The experiments were carried out at the Angara-5-1 facility at currents of up to 3 MA. Analysis of the spatial distribution of hard X-ray emission with photon energies above 20 keV in the pinch images taken during the implosion of quasi-spherical tungsten wire arrays (QTWAs) showed that a compact quasi-spherical plasma object symmetric with respect to the array axis formed in the central region of the array. Using a diffractionmore » grazing incidence spectrograph, spectra of SXR emission with wavelengths of 20–400 Å from the central, axial, and peripheral regions of the emission source were measured with spatial resolutions along the array radius and height in the implosion of QTWAs. It is shown that the emission spectra of the SXR sources formed under the implosion of quasi-spherical and cylindrical tungsten wire arrays at currents of up to 3 MA have a maximum in the wavelength range of 50–150 Å. It is found that, during the implosion of a QTWA with a profiled linear mass, a redistribution of energy in the emission spectrum takes place, which indicates that, during 3D implosion, the energy of longitudinal motion of the array material additionally contributes to the radiation energy. It is also found that, at close masses of the arrays and close values of the current in the range of 2.4{sup −3} MA, the average energy density in the emission source formed during the implosion of a quasi-spherical wire array is larger by a factor of 7 than in the source formed during the implosion of a cylindrical wire array. The experimental data were compared with results of 3D simulations of plasma dynamics and radiation generation during the implosion of quasi-spherical wire arrays with a profiled mass by using the MARPLE-3D radiative magnetohydrodynamic code, developed at the Keldysh Institute of Applied Mathematics, Russian Academy of Sciences.« less

High-voltage plasma interactions calculations using NASCAP/LEO

NASA Technical Reports Server (NTRS)

Mandell, M. J.; Katz, I.

1990-01-01

This paper reviews four previous simulations (two laboratory and two space-flight) of interactions of a high-voltage spacecraft with a plasma under low-earth orbit conditions, performed using a three-dimensional computer code NASCAP/LEO. Results show that NASCAP/LEO can perform meaningful simulations of high-voltage plasma interactions taking into account three-dimensional effects of geometry, spacecraft motion, and magnetic field. Two new calculations are presented: (1) for current collection by 1-mm pinholes in wires (showing that a pinhole in a wire can collect far more current than a similar pinhole in a flat plate); and (2) current collection by Charge-2 mother vehicle launched in December 1985. It is shown that the Charge-2 calculations predicted successfully ion collection at negative bias, the floating potential of a probe outside or inside the sheath under negative bias conditions, and magnetically limited electron collection under electron beam operation at high altitude.

An evaluation of the electric arc spray and (HPPS) processes for the manufacturing of high power plasma spraying MCrAIY coatings

NASA Astrophysics Data System (ADS)

Sacriste, D.; Goubot, N.; Dhers, J.; Ducos, M.; Vardelle, A.

2001-06-01

The high power plasma torch (PlazJet) can be used to spray refractory ceramics with high spray rates and deposition efficiency. It can provide dense and hard coating with high bond strengths. When manufacturing thermal barrier coatings, the PlazJet gun is well adapted to spraying the ceramic top coat but not the MCrAIY materials that are used as bond coat. Arc spraying can compete with plasma spraying for metallic coatings since cored wires can be used to spray alloys and composites. In addition, the high production rate of arc spraying enables a significant decrease in coating cost. This paper discusses the performances of the PlazJet gun, and a twin-wire are spray system, and compares the properties and cost of MCrAIY coatings made with these two processes. For arc spraying, the use of air or nitrogen as atomizing gas is also investigated.

Monolithic exploding foil initiator

DOEpatents

Welle, Eric J; Vianco, Paul T; Headley, Paul S; Jarrell, Jason A; Garrity, J. Emmett; Shelton, Keegan P; Marley, Stephen K

2012-10-23

A monolithic exploding foil initiator (EFI) or slapper detonator and the method for making the monolithic EFI wherein the exploding bridge and the dielectric from which the flyer will be generated are integrated directly onto the header. In some embodiments, the barrel is directly integrated directly onto the header.

Rethinking Use of the OML Model in Electric Sail Development

NASA Technical Reports Server (NTRS)

Stone, Nobie H.

2016-01-01

In 1924, Irvin Langmuir and H. M. Mott-Smith published a theoretical model for the complex plasma sheath phenomenon in which they identified some very special cases which greatly simplified the sheath and allowed a closed solution to the problem. The most widely used application is for an electrostatic, or "Langmuir," probe in laboratory plasma. Although the Langmuir probe is physically simple (a biased wire) the theory describing its functional behavior and its current-voltage characteristic is extremely complex and, accordingly, a number of assumptions and approximations are used in the LMS model. These simplifications, correspondingly, place limits on the model's range of application. Adapting the LMS model to real-life conditions is the subject of numerous papers and dissertations. The Orbit-Motion Limited (OML) model that is widely used today is one of these adaptions that is a convenient means of calculating sheath effects. Since the Langmuir probe is a simple biased wire immersed in plasma, it is particularly tempting to use the OML equation in calculating the characteristics of the long, highly biased wires of an Electric Sail in the solar wind plasma. However, in order to arrive at the OML equation, a number of additional simplifying assumptions and approximations (beyond those made by Langmuir-Mott-Smith) are necessary. The OML equation is a good approximation when all conditions are met, but it would appear that the Electric Sail problem lies outside of the limits of applicability.

Generation of cylindrically convergent shockwaves in water on the MACH facility

NASA Astrophysics Data System (ADS)

Bland, Simon; Krasik, Ya. E.; Yanuka, D.; Gardner, R.; MacDonald, J.; Virozub, A.; Efimov, S.; Gleizer, S.; Chaturvedi, N.

2017-06-01

We report on the first experiments utilizing MACH facility at Imperial College London to explode copper wire arrays in water, generating extremely symmetric, cylindrical convergent shockwaves. The experiments were carried out with 10mm diameter arrays consisting of 60 × 130 μm wires, and currents >500 kA were achieved despite the high inductance load. Laser backlit framing images and streak photography of the implosion showed a highly uniform, stable shockwave that travelled towards the axis at velocities up to 7.5 kms-1. For the first time, imaging of the shock front has been carried at radii < 0.5 mm, and there is strong evidence that even at radii < 0.1 mm the shock front remains stable, resulting in a convergence ratio of 50:1. 2D hydrodynamic simulations that match the experimentally obtained implosion trajectory suggest pressures of >1 Mbar are produced within 10 μm of the axis, with water densities 3 gcm-3 and temperatures of many 1000 s of Kelvin. The results represent a significant step in the application of the technique to drive different material samples, and calculations of scaling the technique to larger pulsed power facilities are presented. This work was supported by the Institute of Shock Physics, funded by AWE Aldermaston, and the NNSA under DOE Cooperative Agreement Nos. DE-F03-02NA00057 and DE-SC-0001063.

Exploding head syndrome is common in college students.

PubMed

Sharpless, Brian A

2015-08-01

Exploding head syndrome is characterized by the perception of loud noises during sleep-wake or wake-sleep transitions. Although episodes by themselves are relatively harmless, it is a frightening phenomenon that may result in clinical consequences. At present there are little systematic data on exploding head syndrome, and prevalence rates are unknown. It has been hypothesized to be rare and to occur primarily in older (i.e. 50+ years) individuals, females, and those suffering from isolated sleep paralysis. In order to test these hypotheses, 211 undergraduate students were assessed for both exploding head syndrome and isolated sleep paralysis using semi-structured diagnostic interviews: 18.00% of the sample experienced lifetime exploding head syndrome, this reduced to 16.60% for recurrent cases. Though not more common in females, it was found in 36.89% of those diagnosed with isolated sleep paralysis. Exploding head syndrome episodes were accompanied by clinically significant levels of fear, and a minority (2.80%) experienced it to such a degree that it was associated with clinically significant distress and/or impairment. Contrary to some earlier theorizing, exploding head syndrome was found to be a relatively common experience in younger individuals. Given the potential clinical impacts, it is recommended that it be assessed more regularly in research and clinical settings. © 2015 European Sleep Research Society.

Unique Results and Lessons Learned from the TSS Missions

NASA Technical Reports Server (NTRS)

Stone, Nobie H.

2016-01-01

In 1924, Irvin Langmuir and H. M. Mott-Smith published a theoretical model for the complex plasma sheath phenomenon in which they identified some very special cases which greatly simplified the sheath and allowed a closed solution to the problem. The most widely used application is for an electrostatic, or "Langmuir," probe in laboratory plasma. Although the Langmuir probe is physically simple (a biased wire) the theory describing its functional behavior and its current-voltage characteristic is extremely complex and, accordingly, a number of assumptions and approximations are used in the LMS model. These simplifications, correspondingly, place limits on the model's range of application. Adapting the LMS model to real-life conditions is the subject of numerous papers and dissertations. The Orbit-Motion Limited (OML) model that is widely used today is one of these adaptions that is a convenient means of calculating sheath effects. The OML equation for electron current collection by a positively biased body is simply: I is approximately equal to A x j(sub eo) x 2/v??(phi)(exp ½) where A is the area of the body and phi is the electric potential on the body with respect to the plasma. Since the Langmuir probe is a simple biased wire immersed in plasma, it is particularly tempting to use the OML equation in calculating the characteristics of the long, highly biased wires of an Electric Sail in the solar wind plasma. However, in order to arrive at the OML equation, a number of additional simplifying assumptions and approximations (beyond those made by Langmuir-Mott-Smith) are necessary. The OML equation is a good approximation when all conditions are met, but it would appear that the Electric Sail problem lies outside of the limits of applicability.

Ponderomotive ion acceleration in dense magnetized laser-irradiated thick target plasmas

NASA Astrophysics Data System (ADS)

Sinha, Ujjwal; Kaw, Predhiman

2012-03-01

When a circularly polarized laser pulse falls on an overdense plasma, it displaces the electrons via ponderomotive force creating a double layer. The double layer constitutes of an ion and electron sheath with in which the electrostatic field present is responsible for ion acceleration. In this paper, we have analyzed the effect a static longitudinal magnetic field has over the ion acceleration mechanism. The longitudinal magnetic field changes the plasma dielectric constant due to cyclotron effects which in turn enhances or reduces the ponderomotive force exerted by the laser depending on whether the laser is left or right circularly polarized. Also, the analysis of the ion space charge region present behind the ion sheath of the laser piston that undergoes coulomb explosion has been explored for the first time. We have studied the interaction of an incoming ion beam with the laser piston and the ion space charge. It has been found that the exploding ion space charge has the ability to act as an energy amplifier for incoming ion beams.

[Contrast of Z-Pinch X-Ray Yield Measure Technique].

PubMed

Li, Mo; Wang, Liang-ping; Sheng, Liang; Lu, Yi

2015-03-01

Resistive bolometer and scintillant detection system are two mainly Z-pinch X-ray yield measure techniques which are based on different diagnostic principles. Contrasting the results from two methods can help with increasing precision of X-ray yield measurement. Experiments with different load material and shape were carried out on the "QiangGuang-I" facility. For Al wire arrays, X-ray yields measured by the two techniques were largely consistent. However, for insulating coating W wire arrays, X-ray yields taken from bolometer changed with load parameters while data from scintillant detection system hardly changed. Simulation and analysis draw conclusions as follows: (1) Scintillant detection system is much more sensitive to X-ray photons with low energy and its spectral response is wider than the resistive bolometer. Thus, results from the former method are always larger than the latter. (2) The responses of the two systems are both flat to Al plasma radiation. Thus, their results are consistent for Al wire array loads. (3) Radiation form planar W wire arrays is mainly composed of sub-keV soft X-ray. X-ray yields measured by the bolometer is supposed to be accurate because of the nickel foil can absorb almost all the soft X-ray. (4) By contrast, using planar W wire arrays, data from scintillant detection system hardly change with load parameters. A possible explanation is that while the distance between wires increases, plasma temperature at stagnation reduces and spectra moves toward the soft X-ray region. Scintillator is much more sensitive to the soft X-ray below 200 eV. Thus, although the total X-ray yield reduces with large diameter load, signal from the scintillant detection system is almost the same. (5) Both Techniques affected by electron beams produced by the loads.

First Experiments with Planar Wire Arrays on U Michigan's Linear Transformer Driver

NASA Astrophysics Data System (ADS)

Safronova, A. S.; Kantsyrev, V. L.; Weller, M. E.; Shrestha, I. K.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M.; Stafford, A.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Jordan, N. M.; Gilgenbach, R. M.

2014-10-01

For petawatt-class Z-pinch accelerators, a Linear Transformer Driver (LTD)-driven accelerator promises to be (at a given pinch current and implosion time) more efficient than the conventionally used Marx-driven accelerator. Because there exists almost no data on how wire arrays radiate on LTD-based machines in the USA, it is very important to perform radiation and plasma physics studies on this new type of generator. We report on the first outcome of the new partnership with University of Michigan (UM), which resulted in successful UNR-UM experiments on the low-impedance MAIZE generator with planar wire arrays (PWA). PWA is a novel wire array load that was introduced and tested in detail on high-impedance Zebra at UNR during the last years and found to be the most efficient radiator. Implosion of Al Double PWAs of different configurations were achieved on MAIZE, observed with a set of various diagnostics which include x-ray diode detectors, x-ray spectroscopy and imaging, and shadowgraphy. Al and Mg plasmas of more than 450 eV were studied in detail. Research supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. G. Patel and A. M. Steiner supported by Sandia National Laboratories. D. A. Yager-Elorriaga supported by NSF GF.

Comparative properties of the interior and blowoff plasmas in a dynamic hohlraum

DOE PAGES

Apruzese, J. P.; Clark, R. W.; Davis, J.; ...

2007-04-20

A Dynamic Hohlraum (DH) is formed when arrays of tungsten wires driven by a high-current pulse implode and compress a cylindrical foam target. The resulting radiation is confined by the wire plasma and forms an intense, ~200–250 eV Planckian x-ray source. The internal radiation can be used for indirect drive inertial confinement fusion. The radiation emitted from the ends can be employed for radiation flow and material interaction studies. This external radiation is accompanied by an expanding blowoff plasma. In this paper, we have diagnosed this blowoff plasma using K-shell spectra of Mg tracer layers placed at the ends ofmore » some of the Dynamic Hohlraum targets. A similar diagnosis of the interior hohlraum has been carried out using Al and Mg tracers placed at 2mm depth from the ends. It is found that the blowoff plasma is about 20–25% as dense as that of the interior hohlraum, and that its presence does not significantly affect the outward flow of the nearly Planckian radiation field generated in the hohlraum interior. Finally, however, the electron temperature of the blowoff region, at ~120 eV, is only about half that of the interior hohlraum plasma.« less

Lightweight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

DTIC Science & Technology

2014-10-01

34Optical study of radicals (OH, O, H, N) in a needle- plate negative pulsed streamer corona discharge ," Plasma Chemistry and Plasma Processing, vol. 26...pulsed corona discharge ," European Physical Journal D, vol. 38, pp. 515-522, Jun 2006. [35] W. Wang, S. Wang, F. Liu, W. Zheng, and D. Wang, "Optical...study of OH radical in a wire-plate pulsed corona discharge ," Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, vol. 63, pp. 477

A Chandrasekhar Mass Progenitor for the Type Ia Supernova Remnant 3C 397 from the Enhanced Abundances of Nickel and Manganese

NASA Technical Reports Server (NTRS)

Yamaguchi, Hiroya; Badenes, Carles; Foster, Adam R.; Bravo, Eduardo; Williams, Brian J.; Maeda, Keiichi; Nobukawa, Masayoshi; Eriksen, Kristoffer A.; Brickhouse, Nancy S.; Petre, Robert;

25 CFR 11.409 - Reckless burning or exploding.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 25 Indians 1 2013-04-01 2013-04-01 false Reckless burning or exploding. 11.409 Section 11.409 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER COURTS OF INDIAN OFFENSES AND LAW AND ORDER CODE Criminal Offenses § 11.409 Reckless burning or exploding. A person commits a...

25 CFR 11.409 - Reckless burning or exploding.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 25 Indians 1 2011-04-01 2011-04-01 false Reckless burning or exploding. 11.409 Section 11.409 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER COURTS OF INDIAN OFFENSES AND LAW AND ORDER CODE Criminal Offenses § 11.409 Reckless burning or exploding. A person commits a...

25 CFR 11.409 - Reckless burning or exploding.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Reckless burning or exploding. 11.409 Section 11.409 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER COURTS OF INDIAN OFFENSES AND LAW AND ORDER CODE Criminal Offenses § 11.409 Reckless burning or exploding. A person commits a...

25 CFR 11.409 - Reckless burning or exploding.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 25 Indians 1 2012-04-01 2011-04-01 true Reckless burning or exploding. 11.409 Section 11.409 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER COURTS OF INDIAN OFFENSES AND LAW AND ORDER CODE Criminal Offenses § 11.409 Reckless burning or exploding. A person commits a...

25 CFR 11.409 - Reckless burning or exploding.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 25 Indians 1 2014-04-01 2014-04-01 false Reckless burning or exploding. 11.409 Section 11.409 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER COURTS OF INDIAN OFFENSES AND LAW AND ORDER CODE Criminal Offenses § 11.409 Reckless burning or exploding. A person commits a...

A New Take on Exploding Carts

ERIC Educational Resources Information Center

Broder, Darren; Burleigh, James; Christian, Matthew; Mowry, Shawn; Hassel, George E.

2017-01-01

The Exploding Carts is a popular introductory physics activity in which a one-dimensional explosion is simulated utilizing two dynamics carts that are pushed apart by a spring-loaded plunger released from one of the carts. Traditional treatments of the Exploding Carts usually involve multiple trials where the mass of one or both of the carts is…

Massive stars: flare activity due to infalls of comet-like bodies

NASA Astrophysics Data System (ADS)

Ibadov, Subhon; Ibodov, Firuz S.

2015-01-01

Passages of comet-like bodies through the atmosphere/chromosphere of massive stars at velocities more than 600 km/s will be accompanied, due to aerodynamic effects as crushing and flattening, by impulse generation of hot plasma within a relatively very thin layer near the stellar surface/photosphere as well as ``blast'' shock wave, i.e., impact-generated photospheric stellar/solar flares. Observational manifestations of such high-temperature phenomena will be eruption of the explosive layer's hot plasma, on materials of the star and ``exploding'' comet nuclei, into the circumstellar environment and variable anomalies in chemical abundances of metal atoms/ions like Fe, Si etc. Interferometric and spectroscopic observations/monitoring of young massive stars with dense protoplanetary discs are of interest for massive stars physics/evolution, including identification of mechanisms for massive stars variability.

Transient fields produced by a cylindrical electron beam flowing through a plasma

NASA Astrophysics Data System (ADS)

Firpo, Marie-Christine

2012-10-01

Fast ignition schemes (FIS) for inertial confinement fusion should involve in their final stage the interaction of an ignition beam composed of MeV electrons laser generated at the critical density surface with a dense plasma target. In this study, the out-of-equilibrium situation in which an initially sharp-edged cylindrical electron beam, that could e.g. model electrons flowing within a wire [1], is injected into a plasma is considered. A detailed computation of the subsequently produced magnetic field is presented [2]. The control parameter of the problem is shown to be the ratio of the beam radius to the electron skin depth. Two alternative ways to address analytically the problem are considered: one uses the usual Laplace transform approach, the other one involves Riemann's method in which causality conditions manifest through some integrals of triple products of Bessel functions.[4pt] [1] J.S. Green et al., Surface heating of wire plasmas using laser-irradiated cone geometries, Nature Physics 3, 853--856 (2007).[0pt] [2] M.-C. Firpo, http://hal.archives-ouvertes.fr/hal-00695629, to be published (2012).

Optimal Design of Magnetic ComponentsinPlasma Cutting Power Supply

NASA Astrophysics Data System (ADS)

Jiang, J. F.; Zhu, B. R.; Zhao, W. N.; Yang, X. J.; Tang, H. J.

2017-10-01

Phase-shifted transformer and DC reactor are usually needed in chopper plasma cutting power supply. Because of high power rate, the loss of magnetic components may reach to several kilowatts, which seriously affects the conversion efficiency. Therefore, it is necessary to research and design low loss magnetic components by means of efficient magnetic materials and optimal design methods. The main task in this paper is to compare the core loss of different magnetic material, to analyze the influence of transformer structure, winding arrangement and wire structure on the characteristics of magnetic component. Then another task is to select suitable magnetic material, structure and wire in order to reduce the loss and volume of magnetic components. Based on the above outcome, the optimization design process of transformer and dc reactor are proposed in chopper plasma cutting power supply with a lot of solutions. These solutions are analyzed and compared before the determination of the optimal solution in order to reduce the volume and power loss of the two magnetic components and improve the conversion efficiency of plasma cutting power supply.

Control of surface defects on plasma-MIG hybrid welds in cryogenic aluminum alloys

NASA Astrophysics Data System (ADS)

Lee, Hee-Keun; Chun, Kwang-San; Park, Sang-Hyeon; Kang, Chung-Yun

2015-07-01

Lately, high production rate welding processes for Al alloys, which are used as LNG FPSO cargo containment system material, have been developed to overcome the limit of installation and high rework rates. In particular, plasma-metal inert gas (MIG) hybrid (PMH) welding can be used to obtain a higher deposition rate and lower porosity, while facilitating a cleaning effect by preheating and post heating the wire and the base metal. However, an asymmetric undercut and a black-colored deposit are created on the surface of PMH weld in Al alloys. For controlling the surface defect formation, the wire feeding speed and nozzle diameter in the PMH weld was investigated through arc phenomena with high-speed imaging and metallurgical analysis.

Exploding Head Syndrome in the Epilepsy Monitoring Unit: Case Report and Literature Review.

PubMed

Gillis, Kara; Ng, Marcus C

2017-01-01

Diagnosis of paroxysmal events in epilepsy patients is often made through video-telemetry electroencephalography in the epilepsy monitoring unit. This case report describes the first-ever diagnosis of exploding head syndrome in a patient with longstanding epilepsy and novel nocturnal events. In this report, we describe the presentation of exploding head syndrome and its prevalence and risk factors. In addition, the prevalence of newly diagnosed sleep disorders through video-telemetry electroencephalography in the epilepsy monitoring unit is briefly reviewed. This report also illustrates the novel use of clobazam for the treatment of exploding head syndrome.

Topiramate Responsive Exploding Head Syndrome

PubMed Central

Palikh, Gaurang M.; Vaughn, Bradley V.

2010-01-01

Exploding head syndrome is a rare phenomenon but can be a significant disruption to quality of life. We describe a 39-year-old female with symptoms of a loud bang and buzz at sleep onset for 3 years. EEG monitoring confirmed these events occurred in transition from stage 1 sleep. This patient reported improvement in intensity of events with topiramate medication. Based on these results, topiramate may be an alternative method to reduce the intensity of events in exploding head syndrome. Citation: Palikh GM; Vaughn BV. Topiramate responsive exploding head syndrome. J Clin Sleep Med 2010;6(4):382-383. PMID:20726288

Exploding head syndrome.

PubMed

Sharpless, Brian A

2014-12-01

Exploding head syndrome is characterized by the perception of abrupt, loud noises when going to sleep or waking up. They are usually painless, but associated with fear and distress. In spite of the fact that its characteristic symptomatology was first described approximately 150 y ago, exploding head syndrome has received relatively little empirical and clinical attention. Therefore, a comprehensive review of the scientific literature using Medline, PsycINFO, Google Scholar, and PubMed was undertaken. After first discussing the history, prevalence, and associated features, the available polysomnography data and five main etiological theories for exploding head syndrome are summarized. None of these theories has yet reached dominance in the field. Next, the various methods used to assess and treat exploding head syndrome are discussed, as well as the limited outcome data. Finally, recommendations for future measure construction, treatment options, and differential diagnosis are provided. Copyright © 2014 Elsevier Ltd. All rights reserved.

Transport of energy by ultraintense laser-generated electrons in nail-wire targets

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

Ma, T.; Lawrence Livermore National Laboratory, Livermore, California 94550; Key, M. H.

2009-11-15

Nail-wire targets (20 {mu}m diameter copper wires with 80 {mu}m hemispherical head) were used to investigate energy transport by relativistic fast electrons generated in intense laser-plasma interactions. The targets were irradiated using the 300 J, 1 ps, and 2x10{sup 20} W{center_dot}cm{sup -2} Vulcan laser at the Rutherford Appleton Laboratory. A spherically bent crystal imager, a highly ordered pyrolytic graphite spectrometer, and single photon counting charge-coupled device gave absolute Cu K{alpha} measurements. Results show a concentration of energy deposition in the head and an approximately exponential fall-off along the wire with about 60 {mu}m 1/e decay length due to resistive inhibition.more » The coupling efficiency to the wire was 3.3{+-}1.7% with an average hot electron temperature of 620{+-}125 keV. Extreme ultraviolet images (68 and 256 eV) indicate additional heating of a thin surface layer of the wire. Modeling using the hybrid E-PLAS code has been compared with the experimental data, showing evidence of resistive heating, magnetic trapping, and surface transport.« less

Coating Bores of Light Metal Engine Blocks with a Nanocomposite Material using the Plasma Transferred Wire Arc Thermal Spray Process

NASA Astrophysics Data System (ADS)

Bobzin, K.; Ernst, F.; Zwick, J.; Schlaefer, T.; Cook, D.; Nassenstein, K.; Schwenk, A.; Schreiber, F.; Wenz, T.; Flores, G.; Hahn, M.

2008-09-01

Engine blocks of modern passenger car engines are generally made of light metal alloys, mostly hypoeutectic AlSi-alloys. Due to their low hardness, these alloys do not meet the tribological requirements of the system cylinder running surface—piston rings—lubricating oil. In order to provide a suitable cylinder running surface, nowadays cylinder liners made of gray cast iron are pressed in or cast into the engine block. A newer approach is to apply thermal spray coatings onto the cylinder bore walls. Due to the geometric conditions, the coatings are applied with specifically designed internal diameter thermal spray systems. With these processes a broad variety of feedstock can be applied, whereas mostly low-alloyed carbon steel feedstock is being used for this application. In the context of this work, an iron-based wire feedstock has been developed, which leads to a nanocrystalline coating. The application of this material was carried out with the Plasma Transferred Wire Arc system. AlMgSi0.5 liners were used as substrates. The coating microstructure and the properties of the coatings were analyzed.

Tapered monocapillary-optics for point source applications

DOEpatents

Hirsch, Gregory

2000-01-01

A glass or metal wire is precisely etched to form the paraboloidal or ellipsoidal shape of the final desired capillary optic. This shape is created by carefully controlling the withdrawal speed of the wire from an etchant bath. In the case of a complete ellipsoidal capillary, the etching operation is performed twice in opposite directions on adjacent wire segments. The etched wire undergoes a subsequent operation to create an extremely smooth surface. This surface is coated with a layer of material which is selected to maximize the reflectivity of the radiation. This reflective surface may be a single layer for wideband reflectivity, or a multilayer coating for optimizing the reflectivity in a narrower wavelength interval. The coated wire is built up with a reinforcing layer, typically by a plating operation. The initial wire is removed by either an etching procedure or mechanical force. Prior to removing the wire, the capillary is typically bonded to a support substrate. One option for attaching the wire to the substrate produces a monolithic structure by essentially burying it under a layer of plating which covers both the wire and the substrate. The capillary optic is used for efficiently collecting and redirecting the divergent radiation from a source which could be the anode of an x-ray tube, a plasma source, the fluorescent radiation from an electron microprobe, or some other source of radiation.

Multicolor, time-gated, soft x-ray pinhole imaging of wire array and gas puff Z pinches on the Z and Saturn pulsed power generators.

PubMed

Jones, B; Coverdale, C A; Nielsen, D S; Jones, M C; Deeney, C; Serrano, J D; Nielsen-Weber, L B; Meyer, C J; Apruzese, J P; Clark, R W; Coleman, P L

2008-10-01

A multicolor, time-gated, soft x-ray pinhole imaging instrument is fielded as part of the core diagnostic set on the 25 MA Z machine [M. E. Savage et al., in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, New York, 2007), p. 979] for studying intense wire array and gas puff Z-pinch soft x-ray sources. Pinhole images are reflected from a planar multilayer mirror, passing 277 eV photons with <10 eV bandwidth. An adjacent pinhole camera uses filtration alone to view 1-10 keV photons simultaneously. Overlaying these data provides composite images that contain both spectral as well as spatial information, allowing for the study of radiation production in dense Z-pinch plasmas. Cu wire arrays at 20 MA on Z show the implosion of a colder cloud of material onto a hot dense core where K-shell photons are excited. A 528 eV imaging configuration has been developed on the 8 MA Saturn generator [R. B. Spielman et al., and A. I. P. Conf, Proc. 195, 3 (1989)] for imaging a bright Li-like Ar L-shell line. Ar gas puff Z pinches show an intense K-shell emission from a zippering stagnation front with L-shell emission dominating as the plasma cools.

Study of Plasma Flow Modes in Imploding Nested Arrays

NASA Astrophysics Data System (ADS)

Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Branitsky, A. V.; Frolov, I. N.; Grabovski, E. V.; Sasorov, P. V.; Ol'khovskaya, O. G.; Zaitsev, V. I.

2018-02-01

Results from experimental studies of implosion of nested wire and fiber arrays at currents of up to 4 MA at the Angara-5-1 facility are presented. Depending on the ratio between the radii of the inner and outer arrays, different modes of the plasma flow in the space between the inner and outer arrays were implemented: the sub-Alfvénic ( V r < V A ) and super-Alfvénic ( V r > V A ) modes and a mode with the formation of the transition shock wave (SW) region between the cascades. By varying the material of the outer array (tungsten wires or kapron fibers), it is shown that the plasma flow mode between the inner and outer arrays depends on the ratio between the plasma production rates ṁ in / ṁ out in the inner and outer arrays. The obtained experimental results are compared with the results of one-dimensional MHD simulation of the plasma flow between the arrays. Stable implosion of the inner array plasma was observed in experiments with combined nested arrays consisting of a fiber outer array and a tungsten inner array. The growth rates of magnetic Rayleigh-Taylor (MRT) instability in the inner array plasma at different numbers of fibers in the outer array and different ratios between the radii of the inner and outer arrays are compared. Suppression of MRT instability during the implosion of the inner array plasma results in the formation of a stable compact Z-pinch and generation of a soft X-ray pulse. A possible scenario of interaction between the plasmas of the inner and outer arrays is offered. The stability of the inner array plasma in the stage of final compression depends on the character of interaction of plasma jets from the outer array with the magnetic field of the inner array.

Evaluation of electrical conductivity of Cu and Al through sub microsecond underwater electrical wire explosion

NASA Astrophysics Data System (ADS)

Sheftman, D.; Shafer, D.; Efimov, S.; Krasik, Ya. E.

2012-03-01

Sub-microsecond timescale underwater electrical wire explosions using Cu and Al materials have been conducted. Current and voltage waveforms and time-resolved streak images of the discharge channel, coupled to 1D magneto-hydrodynamic simulations, have been used to determine the electrical conductivity of the metals for the range of conditions between hot liquid metal and strongly coupled non-ideal plasma, in the temperature range of 10-60 KK. The results of these studies showed that the conductivity values obtained are typically lower than those corresponding to modern theoretical electrical conductivity models and provide a transition between the conductivity values obtained in microsecond time scale explosions and those obtained in nanosecond time scale wire explosions. In addition, the measured wire expansion shows good agreement with equation of state tables.

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

Li Zhenghong; Xu Rongkun; Chu Yanyun

Ablation processes of ribbon-array loads, as well as wire-array loads for comparison, were investigated on Qiangguang-1 accelerator. The ultraviolet framing images indicate that the ribbon-array loads have stable passages of currents, which produce axially uniform ablated plasma. The end-on x-ray framing camera observed the azimuthally modulated distribution of the early ablated ribbon-array plasma and the shrink process of the x-ray radiation region. Magnetic probes measured the total and precursor currents of ribbon-array and wire-array loads, and there exists no evident difference between the precursor currents of the two types of loads. The proportion of the precursor current to the totalmore » current is 15% to 20%, and the start time of the precursor current is about 25 ns later than that of the total current. The melting time of the load material is about 16 ns, when the inward drift velocity of the ablated plasma is taken to be 1.5 Multiplication-Sign 10{sup 7} cm/s.« less

Regional rat brain noradrenaline turnover in response to restraint stress.

PubMed

Glavin, G B; Tanaka, M; Tsuda, A; Kohno, Y; Hoaki, Y; Nagasaki, N

1983-08-01

Male Wistar rats were starved for 12 hr and then subjected to either 2 hr of wire mesh "envelope" restraint at room temperature; 2 hr of supine restraint in a specially constructed harness at room temperature or were not restrained. Eight brain regions were examined for NA level and the level of its major metabolite, MHPG-SO4. Plasma corticosterone and gastric ulcer incidence were also measured. All restrained rats displayed marked elevations in MHPG-SO4 levels in most brain regions. In addition, several brain regions in restrained animals showed a reduction in NA level. All restrained rats showed elevated plasma corticosterone levels and evidence of gastric lesions. In general, supine restraint produced greater alterations in regional brain NA turnover, greater evidence of ulcer disease, and higher plasma corticosterone levels than did wire mesh restraint. These data suggest that acute but intense stress in the form of restraint causes markedly altered brain NA activity--a possible neurochemical mechanism underlying the phenomenon of stress-induced disease.

Spectroscopy of Al wire array stagnation on Z

NASA Astrophysics Data System (ADS)

Jones, B.; Jennings, C. A.; Hansen, S. B.; Bailey, J. E.; Rochau, G. A.; Coverdale, C. A.; Yu, E. P.; Ampleford, D. J.; Cuneo, M. E.; Maron, Y.; Fisher, V. I.; Bernshtam, V.; Starobinets, A.; Weingarten, L.; Pinhas, S.

2011-10-01

In this work, we present analysis of time-gated spectra of ~2 keV K-shell emissions from Al (5% Mg) wire arrays on Z to provide details of the plasma conditions and dynamics at the onset of stagnation. The plasma is modeled as concentric radial zones, and collisional-radiative modeling with self-consistent radiation transport is used to constrain the temperatures and densities in these regions. A hot ~2 keV plasma core bearing a few percent of the total mass forms at the foot of the x-ray pulse, with participating mass increasing toward peak x-ray power as material arrives on axis with ~50 cm/ μs implosion velocity. The atomic modeling accounts for K-shell line opacity and Doppler effects, and is compared to 3D MHD simulations. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE National Nuclear Security Administration under contract DE-AC04-94AL85000.

Plasma motor generator system

NASA Technical Reports Server (NTRS)

Hite, Gerald E.

1987-01-01

The significant potential advantages of a plasma motor generator system over conventional systems for the generation of electrical power and propulsion for spacecraft in low Earth orbits warrants its further investigation. The two main components of such a system are a long insulated wire and the plasma generating hollow cathodes needed to maintain electrical contact with the ionosphere. Results of preliminary theoretical and experimental investigations of this system are presented. The theoretical work involved the equilibrium configurations of the wire and the nature of small oscillation about these equilibrium positions. A particularly interesting result was that two different configurations are allowed when the current is above a critical value. Experimental investigations were made of the optimal starting and running conditions for the proposed, low current hollow cathodes. Although optimal ranges of temperature, argon pressure and discharge voltage were identified, start up became progressively more difficult. This supposed depletion or contamination of the emissive surface could be countered by the addition of new emissive material.

Degradation of Acid Orange 7 Dye in Two Hybrid Plasma Discharge Reactors

NASA Astrophysics Data System (ADS)

Shen, Yongjun; Lei, Lecheng; Zhang, Xingwang; Ding, Jiandong

2014-11-01

To get an optimized pulsed electrical plasma discharge reactor and to increase the energy utilization efficiency in the removal of pollutants, two hybrid plasma discharge reactors were designed and optimized. The reactors were compared via the discharge characteristics, energy transfer efficiency, the yields of the active species and the energy utilization in dye wastewater degradation. The results showed that under the same AC input power, the characteristics of the discharge waveform of the point-to-plate reactor were better. Under the same AC input power, the two reactors both had almost the same peak voltage of 22 kV. The peak current of the point-to-plate reactor was 146 A, while that of the wire-to-cylinder reactor was only 48.8 A. The peak powers of the point-to-plate reactor and the wire-to-cylinder reactor were 1.38 MW and 1.01 MW, respectively. The energy per pulse of the point-to-plate reactor was 0.2221 J, which was about 29.4% higher than that of the wire-to-cylinder reactor (0.1716 J). To remove 50% Acid Orange 7 (AO7), the energy utilizations of the point-to-plate reactor and the wire-to-cylinder reactor were 1.02 × 10-9 mol/L and 0.61 × 10-9 mol/L, respectively. In the point-to-plate reactor, the concentration of hydrogen peroxide in pure water was 3.6 mmol/L after 40 min of discharge, which was higher than that of the wire-to-cylinder reactor (2.5 mmol/L). The concentration of liquid phase ozone in the point-to-plate reactor (5.7 × 10-2 mmol/L) was about 26.7% higher than that in the wire-to-cylinder reactor (4.5 × 10-2 mmol/L). The analysis results of the variance showed that the type of reactor and reaction time had significant impacts on the yields of the hydrogen peroxide and ozone. The main degradation intermediates of AO7 identified by gas chromatography and mass spectrometry (GCMS) were acetic acid, maleic anhydride, p-benzoquinone, phenol, benzoic acid, phthalic anhydride, coumarin and 2-naphthol. Proposed degradation pathways were elucidated in light of the analyzed degradation products.

Numerical simulations of Z-Pinch experiments to create supersonic differentially-rotating plasma flows

NASA Astrophysics Data System (ADS)

Bocchi, M.; Ummels, B.; Chittenden, J. P.; Lebedev, S. V.

2012-02-01

In the context of high energy density laboratory astrophysics, we aim to produce and study a rotating plasma relevant to accretion discs physics. We devised an experimental setup based on a modified cylindrical wire array and we studied it numerically with the three-dimensional, resistive magneto-hydrodynamic code GORGON. The simulations show that a rotating plasma cylinder is formed, with typical rotation velocity ~35 km/s and Mach number ~5. In addition, the plasma ring is differentially rotating and strongly radiatively cooled. The introduction of external magnetic fields is discussed.

Time resolved Thomson scattering diagnostic of pulsed gas metal arc welding (GMAW) process

NASA Astrophysics Data System (ADS)

Kühn-Kauffeldt, M.; Marquès, J. L.; Schein, J.

2014-11-01

In this work a Thomson scattering diagnostic technique was applied to obtain time resolved electron temperature and density values during a gas metal arc welding (GMAW) process. The investigated GMAW process was run with aluminum wire (AlMg 4,5 Mn) with 1.2 mm diameter as a wire electrode, argon as a shielding gas and peak currents in the range of 400 A. Time resolved measurements could be achieved by triggering the laser pulse at shifted time positions with respect to the current pulse driving the process. Time evaluation of resulting electron temperatures and densities is used to investigate the state of the plasma in different phases of the current pulse and to determine the influence of the metal vapor and droplets on the plasma properties.

Electrical Conductivity of Dense Al, Ti, Fe, Ni, Cu, Mo, Ta, and W Plasmas

DTIC Science & Technology

2011-06-01

for all but tantalum and titanium shows a minimum at approximately 0.01 times solid density, followed by an increase as the density decreases further...internal energy and specific volume. Conductivity is observed to fall as the plasma expands for fixed internal energy, and for all but tantalum and...plasmas formed from elemental metal wires heated rapidly in a water bath by the electric current from discharge of a charged capacitor . Electrical

A Statistical Representation of Pyrotechnic Igniter Output

NASA Astrophysics Data System (ADS)

Guo, Shuyue; Cooper, Marcia

2017-06-01

The output of simplified pyrotechnic igniters for research investigations is statistically characterized by monitoring the post-ignition external flow field with Schlieren imaging. Unique to this work is a detailed quantification of all measurable manufacturing parameters (e.g., bridgewire length, charge cavity dimensions, powder bed density) and associated shock-motion variability in the tested igniters. To demonstrate experimental precision of the recorded Schlieren images and developed image processing methodologies, commercial exploding bridgewires using wires of different parameters were tested. Finally, a statistically-significant population of manufactured igniters were tested within the Schlieren arrangement resulting in a characterization of the nominal output. Comparisons between the variances measured throughout the manufacturing processes and the calculated output variance provide insight into the critical device phenomena that dominate performance. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under contract DE-AC04-94AL85000.

A Comparative Study of Bio Degradation of Various Orthodontic Arch Wires: An In Vitro Study

PubMed Central

Gopikrishnan, S; Melath, Anil; Ajith, V V; Mathews, N Binoy

2015-01-01

Background: Orthodontic wires are the corner stones of the science and art of orthodontics and they remain in the patient’s mouth for a prolonged period of 18-24 months. It is but natural to expect that they will undergo some biodegradation when in the oral environment during that period. This study aims to compare the biodegradation characteristics of four different orthodontic wires, stainless steel, nickel titanium (NiTi), titanium molybdenum alloy (TMA), and copper NiTi and to assess whether these biodegradation products, are within acceptable limits. Materials and Methods: This study involved the incubation of four different wires in artificial saliva and analyzing the amount of metal released from them at the end of a 28 days study period. The metals analyzed for where nickel, chromium, copper, cobalt, manganese, iron, molybdenum, and titanium. The artificial saliva was changed on days 7, 14, and 21 to prevent the saturation of metals in the artificial saliva. At the end of 28 days, these four samples of artificial saliva of each wire were mixed together and analyzed for the eight metals using an inductively coupled plasma spectroscope. Results: The results showed only the release of nickel, chromium, and iron from stainless steel wire, nickel from NiTi wire, nickel, and chromium from copper NiTi and none from TMA wire. Conclusion: The metals released from arch wires are of such minute quantities to be of any biologic hazard. The amount of metals released is well within acceptable biocompatible limits. Though this study has analyzed the biodegradation of various orthodontic wires, orthodontic wires are never used alone in mechanotherapy. Orthodontic wires along with multiband appliance system with which it is always used and in combination with accessories like face bows may release more metals. PMID:25709360

About plasma points' generation in Z-pinch

NASA Astrophysics Data System (ADS)

Afonin, V. I.; Potapov, A. V.; Lazarchuk, V. P.; Murugov, V. M.; Senik, A. V.

1997-05-01

The streak tube study results (at visible and x-ray ranges) of dynamics of fast Z-pinch formed at explosion of metal wire in diode of high current generator are presented. Amplitude of current in the load reached ˜180 kA at increase time ˜50 ns. The results' analysis points to capability of controlling hot plasma points generation process in Z-pinch.

Bundled monocapillary optics

DOEpatents

Hirsch, Gregory

2002-01-01

A plurality of glass or metal wires are precisely etched to form the desired shape of the individual channels of the final polycapillary optic. This shape is created by carefully controlling the withdrawal speed of a group of wires from an etchant bath. The etched wires undergo a subsequent operation to create an extremely smooth surface. This surface is coated with a layer of material which is selected to maximize the reflectivity of the radiation being used. This reflective surface may be a single layer of material, or a multilayer coating for optimizing the reflectivity in a narrower wavelength interval. The collection of individual wires is assembled into a close-packed multi-wire bundle, and the wires are bonded together in a manner which preserves the close-pack configuration, irrespective of the local wire diameter. The initial wires are then removed by either a chemical etching procedure or mechanical force. In the case of chemical etching, the bundle is generally segmented by cutting a series of etching slots. Prior to removing the wire, the capillary array is typically bonded to a support substrate. The result of the process is a bundle of precisely oriented radiation-reflecting hollow channels. The capillary optic is used for efficiently collecting and redirecting the radiation from a source of radiation which could be the anode of an x-ray tube, a plasma source, the fluorescent radiation from an electron microprobe, a synchrotron radiation source, a reactor or spallation source of neutrons, or some other source.

Development of strain gages for use to 1311 K (1900 F)

NASA Technical Reports Server (NTRS)

Lemcoe, M. M.

1974-01-01

A high temperature electric resistance strain gage system was developed and evaluated to 1366 K (2000 F) for periods of at least one hour. Wire fabricated from a special high temperature strain gage alloy (BCL-3), was used to fabricate the gages. Various joining techniques (NASA butt welding, pulse arc, plasma needle arc, and dc parallel gap welding) were investigated for joining gage filaments to each other, gage filaments to lead-tab ribbons, and lead-tab ribbons to lead wires. The effectiveness of a clad-wire concept as a means of minimizing apparent strain of BCL-3 strain gages was investigated by sputtering platinum coatings of varying thicknesses on wire samples and establishing the optimum coating thickness--in terms of minimum resistivity changes with temperature. Finally, the moisture-proofing effectiveness of barrier coatings subjected to elevated temperatures was studied, and one commercial barrier coating (BLH Barrier H Waterproofing) was evaluated.

Use of a wire scanner for monitoring residual gas ionization in Soreq Applied Research Accelerator Facility 20 keV/u proton/deuteron low energy beam transport beam line

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

Vainas, B.; Eliyahu, I.; Weissman, L.

2012-02-15

The ion source end of the Soreq Applied Research Accelerator Facility accelerator consists of a proton/deuteron ECR ion source and a low energy beam transport (LEBT) beam line. An observed reduction of the radio frequency quadrupole transmission with increase of the LEBT current prompted additional study of the LEBT beam properties. Numerous measurements have been made with the LEBT bream profiler wire biased by a variable voltage. Current-voltage characteristics in presence of the proton beam were measured even when the wire was far out of the beam. The current-voltage characteristic in this case strongly resembles an asymmetric diodelike characteristic, whichmore » is typical of Langmuir probes monitoring plasma. The measurement of biased wire currents, outside the beam, enables us to estimate the effective charge density in vacuum.« less

Controlling Arc Length in Plasma Welding

NASA Technical Reports Server (NTRS)

Iceland, W. F.

1986-01-01

Circuit maintains arc length on irregularly shaped workpieces. Length of plasma arc continuously adjusted by control circuit to maintain commanded value. After pilot arc is established, contactor closed and transfers arc to workpiece. Control circuit then half-wave rectifies ac arc voltage to produce dc control signal proportional to arc length. Circuit added to plasma arc welding machines with few wiring changes. Welds made with circuit cleaner and require less rework than welds made without it. Beads smooth and free of inclusions.

Lightweight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

DTIC Science & Technology

2015-12-01

Wang, W. Zheng, and Y. N. Wang, "Optical study of radicals (OH, O, H, N) in a needle-plate negative pulsed streamer corona discharge ," Plasma...needle- plate bi-directional pulsed corona discharge ," European Physical Journal D, vol. 38, pp. 515-522, Jun 2006. 155 [35] W. Wang, S. Wang...F. Liu, W. Zheng, and D. Wang, "Optical study of OH radical in a wire-plate pulsed corona discharge ," Spectrochimica Acta Part A: Molecular and

Sensor for detecting changes in magnetic fields

DOEpatents

Praeg, Walter F.

1981-01-01

A sensor for detecting changes in the magnetic field of the equilibrium-field coil of a Tokamak plasma device comprises a pair of bifilar wires disposed circumferentially, one inside and one outside the equilibrium-field coil. Each is shorted at one end. The difference between the voltages detected at the other ends of the bifilar wires provides a measure of changing flux in the equilibrium-field coil. This difference can be used to detect faults in the coil in time to take action to protect the coil.

Enhancement of Combustion and Flame Stabilization Using Transient Non-Equilibrium Plasma

DTIC Science & Technology

2007-03-31

cathode spot D = diameter of MGA device D= diffusivity of i’h species d = diameter of arc dcoected= diametrically corrected diameter of arc d.rwwd... cathode and anode, stabilization (4) respectively (Fig. 1). A wire was attached to the cathode , which was separated from the outer anode by 2 mm at the...smallest gap (point (1) in Fig. 1). The wire spiraled progressively closer to the cathode , where it was attached at the largest gap between the two

Dynamic polarizability of tungsten atoms reconstructed from fast electrical explosion of fine wires in vacuum

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

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W.

For nanosecond electrical explosion of fine metal wires in vacuum generates calibrated, radially expanded gas cylinders of metal atoms are surrounded by low-density fast expanding plasma corona. Here, a novel integrated-phase technique, based on laser interferometry, provides the dynamic dipole polarizability of metal atoms. This data was previously unavailable for tungsten atoms. Furthermore, an extremely high melting temperature and significant pre-melt electronic emission make these measurements particularly complicated for this refractory metal.

Dynamic polarizability of tungsten atoms reconstructed from fast electrical explosion of fine wires in vacuum

DOE PAGES

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W.

2016-10-12

For nanosecond electrical explosion of fine metal wires in vacuum generates calibrated, radially expanded gas cylinders of metal atoms are surrounded by low-density fast expanding plasma corona. Here, a novel integrated-phase technique, based on laser interferometry, provides the dynamic dipole polarizability of metal atoms. This data was previously unavailable for tungsten atoms. Furthermore, an extremely high melting temperature and significant pre-melt electronic emission make these measurements particularly complicated for this refractory metal.

Thermal emission from a metamaterial wire medium slab.

PubMed

D'Aguanno, G; Mattiucci, N; Alù, A; Argyropoulos, C; Foreman, J V; Bloemer, M J

2012-04-23

We investigate thermal emission from a metamaterial wire medium embedded in a dielectric host and highlight two different regimes for efficient emission, respectively characterized by broadband emission near the effective plasma frequency of the metamaterial, and by narrow-band resonant emission at the band-edge in the Bragg scattering regime. We discuss how to control the spectral position and relative strength of these two emission mechanisms by varying the geometrical parameters of the proposed metamaterial and its temperature. © 2012 Optical Society of America

Interferometric analysis of laboratory photoionized plasmas utilizing supersonic gas jet targets.

NASA Astrophysics Data System (ADS)

Swanson, Kyle James; Ivanov, Vladimir; Mancini, Roberto; Mayes, Daniel C.

2018-06-01

Photoionized plasmas are an important component of active galactic nuclei, x-ray binary systems and other astrophysical objects. Laboratory produced photoionized plasmas have mainly been studied at large scale facilities, due to the need for high intensity broadband x-ray flux. Using supersonic gas jets as targets has allowed university scale pulsed power generators to begin similar research. The two main advantages of this approach with supersonic gas jets include: possibility of a closer location to the x-ray source and no attenuation related to material used for containment and or tamping. Due to these factors, this experimental platform creates a laboratory environment that more closely resembles astrophysical environments. This system was developed at the Nevada Terawatt Facility using the 1 MA pulsed power generator Zebra. Neon, argon, and nitrogen supersonic gas jets are produced approximately 7-8mm from the z-pinch axis. The high intensity broadband x-ray flux produced by the collapse of the z-pinch wire array implosion irradiates the gas jet. Cylindrical wire arrays are made with 4 and 8 gold 10µm thick wire. The z-pinch radiates approximately 12-16kj of x-ray energy, with x-ray photons under 1Kev in energy. The photoionized plasma is measured via x-ray absorption spectroscopy and interferometry. A Mach-Zehnder interferometer is used to the measure neutral density of the jet prior to the zebra shot at a wavelength of 266 nm. A dual channel air-wedge shearing interferometer is used to measure electron density of the ionized gas jet during the shot, at wavelengths of 532nm and 266nm. Using a newly developed interferometric analysis tool, average ionization state maps of the plasma can be calculated. Interferometry for nitrogen and argon show an average ionization state in the range of 3-8. Preliminary x-ray absorption spectroscopy collected show neon absorption lines. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451.

Orthobiologics in Pediatric Sports Medicine.

PubMed

Bray, Christopher C; Walker, Clark M; Spence, David D

2017-07-01

Orthobiologics are biological substances that allow injured muscles, tendons, ligaments, and bone to heal more quickly. They are found naturally in the body; at higher concentrations they can aid in the healing process. These substances include autograft bone, allograft bone, demineralized bone matrix, bone morphogenic proteins, growth factors, stem cells, plasma-rich protein, and ceramic grafts. Their use in sports medicine has exploded in efforts to increase graft incorporation, stimulate healing, and get athletes back to sport with problems including anterior cruciate ligament ruptures, tendon ruptures, cartilage injuries, and fractures. This article reviews orthobiologics and their applications in pediatric sports medicine. Copyright © 2017 Elsevier Inc. All rights reserved.

Long Scalelength Plasmas for LPI Studies at the Nike Laser

NASA Astrophysics Data System (ADS)

Weaver, J. L.; Oh, J.; Bates, J. W.; Schmitt, A. J.; Kehne, D. M.; Wolford, M. F.; Obenschain, S. P.; Serlin, V.; Lehmberg, R. H.; Follett, R. K.; Shaw, J. G.; Myatt, J. F.; McKenty, P. W.; Wei, M. S.; Reynolds, H.; Williams, J.; Tsung, F.

2017-10-01

Studies of laser plasma instabilities (LPI) at the Nike laser have mainly used short pulses, small focal spots, and solid plastic (CH) targets that have yielded maximum gradient scalelengths below 200 microns. The current experimental effort aims to produce larger volume plasmas with 5-10x reduction in the density and velocity gradients as a platform for SBS, SRS, and TPD studies. The next campaign will concentrate on the effects of wavelength shifting and bandwidth changes on CBET in low density (5-10 mg/cm3) CH foam targets. This poster will discuss the development of this new LPI target platform based on modelling with the LPSE code developed at LLE. The presentation will also discuss alternative target schemes (e.g. exploding foils) and improvements to the LPI diagnostic suite and laser operations; for example, a new set of etalons will be available for the next campaign that should double the range of available wavelength shifting. Upgrades to the scattered light spectrometers in general use for LPI studies will also be presented. Work supported by DoE/NNSA.

A Chandrasekhar mass progenitor for the Type Ia supernova remnant 3C 397 from the enhanced abundances of nickel and manganese

DOE PAGES

Yamaguchi, Hiroya; Badenes, Carles; Foster, Adam R.; ...

2015-03-12

Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only bemore » achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Altogether with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.« less

Explosion of thin aluminum foils in air

NASA Astrophysics Data System (ADS)

Baksht, R.; Pokryvailo, A.; Yankelevich, Y.; Ziv, I.

2004-12-01

An inductive-based power supply (240μH, 50kA) was used for the investigation of the foil explosion process in the time range of 0.05ms

A direct-drive exploding-pusher implosion as the first step in development of a monoenergetic charged-particle backlighting platforn at the National Ignition Facility

DOE PAGES

Rosenberg, M. J.; Zylstra, A. B.; Seguin, F. H.; ...

2016-01-18

A thin-glass-shell, D 3He-filled exploding-pusher inertial confinement fusion implosion at the National Ignition Facility (NIF) has been demonstrated as a proton source that serves as a promising first step toward development of a monoenergetic proton, alpha, and triton backlighting platform at the NIF. Among the key measurements, the D3He-proton emission on this experiment (shot N121128) has been well-characterized spectrally, temporally, and in terms of emission isotropy, revealing a highly monoenergetic (ΔE/E~4%) and isotropic source (~3% proton fluence variation and ~0.5% proton energy variation). On a similar shot (N130129, with D 2 fill), the DD-proton spectrum has been obtained as well,more » illustrating that monoenergetic protons of multiple energies may be utilized in a single experiment. In conclusion, these results, and experiments on OMEGA, point toward future steps in the development of a precision, monoenergetic proton, alpha, and triton source that can readily be implemented at the NIF for backlighting a broad range of high energy density physics (HEDP) experiments in which fields and flows are manifest, and also utilized for studies of stopping power in warm dense matter and in classical plasmas.« less

A direct-drive exploding-pusher implosion as the first step in development of a monoenergetic charged-particle backlighting platforn at the National Ignition Facility

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

Rosenberg, M. J.; Zylstra, A. B.; Seguin, F. H.

A thin-glass-shell, D 3He-filled exploding-pusher inertial confinement fusion implosion at the National Ignition Facility (NIF) has been demonstrated as a proton source that serves as a promising first step toward development of a monoenergetic proton, alpha, and triton backlighting platform at the NIF. Among the key measurements, the D3He-proton emission on this experiment (shot N121128) has been well-characterized spectrally, temporally, and in terms of emission isotropy, revealing a highly monoenergetic (ΔE/E~4%) and isotropic source (~3% proton fluence variation and ~0.5% proton energy variation). On a similar shot (N130129, with D 2 fill), the DD-proton spectrum has been obtained as well,more » illustrating that monoenergetic protons of multiple energies may be utilized in a single experiment. In conclusion, these results, and experiments on OMEGA, point toward future steps in the development of a precision, monoenergetic proton, alpha, and triton source that can readily be implemented at the NIF for backlighting a broad range of high energy density physics (HEDP) experiments in which fields and flows are manifest, and also utilized for studies of stopping power in warm dense matter and in classical plasmas.« less

A semi-analytical study of positive corona discharge in wire-plane electrode configuration

NASA Astrophysics Data System (ADS)

Yanallah, K.; Pontiga, F.; Chen, J. H.

2013-08-01

Wire-to-plane positive corona discharge in air has been studied using an analytical model of two species (electrons and positive ions). The spatial distributions of electric field and charged species are obtained by integrating Gauss's law and the continuity equations of species along the Laplacian field lines. The experimental values of corona current intensity and applied voltage, together with Warburg's law, have been used to formulate the boundary condition for the electron density on the corona wire. To test the accuracy of the model, the approximate electric field distribution has been compared with the exact numerical solution obtained from a finite element analysis. A parametrical study of wire-to-plane corona discharge has then been undertaken using the approximate semi-analytical solutions. Thus, the spatial distributions of electric field and charged particles have been computed for different values of the gas pressure, wire radius and electrode separation. Also, the two dimensional distribution of ozone density has been obtained using a simplified plasma chemistry model. The approximate semi-analytical solutions can be evaluated in a negligible computational time, yet provide precise estimates of corona discharge variables.

Topiramate responsive exploding head syndrome.

PubMed

Palikh, Gaurang M; Vaughn, Bradley V

2010-08-15

Exploding head syndrome is a rare phenomenon but can be a significant disruption to quality of life. We describe a 39-year-old female with symptoms of a loud bang and buzz at sleep onset for 3 years. EEG monitoring confirmed these events occurred in transition from stage 1 sleep. This patient reported improvement in intensity of events with topiramate medication. Based on these results, topiramate may be an alternative method to reduce the intensity of events in exploding head syndrome.

Bioethanol production from steam-exploded rice husk by recombinant Escherichia coli KO11.

PubMed

Tabata, Takamitsu; Yoshiba, Yusuke; Takashina, Tomonori; Hieda, Kazuo; Shimizu, Norio

2017-03-01

Rice husk is one of the most abundant types of lignocellulosic biomass. Because of its significant amount of sugars, such as cellulose and hemicellulose, it can be used for the production of biofuels such as bioethanol. However, the complex structure of lignocellulosic biomass, consisting of cellulose, hemicellulose and lignin, is resistant to degradation, which limits biomass utilization for ethanol production. The protection of cellulose by lignin contributes to the recalcitrance of lignocelluloses to hydrolysis. Therefore, we conducted steam-explosion treatment as pretreatment of rice husk. However, recombinant Escherichia coli KO11 did not ferment the reducing sugar solution obtained by enzymatic saccharification of steam-exploded rice husk. When the steam-exploded rice husk was washed with hot water to remove inhibitory substances and M9 medium (without glucose) was used as a fermentation medium, E. coli KO11 completely fermented the reducing sugar solution obtained by enzymatic saccharification of hot water washing-treated steam-exploded rice husk to ethanol. We report here the efficient production of bioethanol using steam-exploded rice husk.

Z pinches as intense x-ray sources for high-energy density physics applications

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

Matzen, M.K.

1997-05-01

Fast Z-pinch implosions can efficiently convert the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator [R. B. Spielman {ital et al.}, in {ital Proceedings of the 2nd International Conference on Dense Z Pinches}, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] at Sandia National Laboratories, for example, currents ofmore » 6{endash}8 MA with a rise time of less than 50 ns are driven through cylindrically symmetric loads, producing implosion velocities as high as 10{sup 8}cm/s and x-ray energies exceeding 400 kJ. Hydromagnetic Rayleigh{endash}Taylor instabilities and cylindrical load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray energies and pulse widths that can be produced on these accelerators. In recent experiments on the Saturn accelerator, these implosion nonuniformities have been minimized by using wire arrays with as many as 192 wires. Increasing the wire number produced significant improvements in the pinched plasma quality, reproducibility, and x-ray output power. X-ray pulse widths of less than 5 ns and peak powers of 75{plus_minus}10TW have been achieved with arrays of 120 tungsten wires. Similar loads have recently been fielded on the Particle Beam Fusion Accelerator (PBFA II), producing x-ray energies in excess of 1.8 MJ at powers in excess of 160 TW. These intense x-ray sources offer the potential for performing many new basic physics and fusion-relevant experiments. {copyright} {ital 1997 American Institute of Physics.}« less

Infectivity of prion protein bound to stainless steel wires: a model for testing decontamination procedures for transmissible spongiform encephalopathies.

PubMed

Yan, Zheng-Xin; Stitz, Lothar; Heeg, Peter; Pfaff, Eberhard; Roth, Klaus

2004-04-01

To establish an animal model to study transmissible spongiform encephalopathy using hamsters and steel wires contaminated with infectious brain materials as transfer vehicles, and, based on this model, to test decontamination procedures against the infectious prion proteins on the steel wires as a near real situation bioassay. Infectious brain materials were given to healthy hamsters intracerebrally either as a suspension or as dried materials on the surface of steel wires. The animals were observed for 18 months. During this period, animals showing definitive clinical signs were euthanized. Decontamination studies were performed by reprocessing contaminated steel wires with different disinfection agents and procedures before implantation. Pathological prion proteins were able to bind to the steel wires and caused disease after the contaminated wires were implanted in the brains of hamsters. When the contaminated wires were treated with different reprocessing procedures before implantation, infectivity was reduced, which was manifested directly by prolonged survival time of the test animals. These results show that this model can be used as a bioassay to validate reprocessing procedures for surgical instruments. At the time of submission of this article, only the group of hamsters incubated with wires reprocessed with an alkaline detergent, followed by sterilization with a modified cycle in a hydrogen peroxide gas plasma sterilizer (4 injections), showed no clinical signs of disease and remained alive. Two animals from the group receiving sodium hydroxide followed by autoclaving (at 134 degrees C for 18 minutes) died. Furthermore, the tested enzymatic cleaning agent seemed to have no positive effect.

Explodator: A new skeleton mechanism for the halate driven chemical oscillators

NASA Astrophysics Data System (ADS)

Noszticzius, Z.; Farkas, H.; Schelly, Z. A.

1984-06-01

In the first part of this work, some shortcomings in the present theories of the Belousov-Zhabotinskii oscillating reaction are discussed. In the second part, a new oscillatory scheme, the limited Explodator, is proposed as an alternative skeleton mechanism. This model contains an always unstable three-variable Lotka-Volterra core (the ``Explodator'') and a stabilizing limiting reaction. The new scheme exhibits Hopf bifurcation and limit cycle oscillations. Finally, some possibilities and problems of a generalization are mentioned.

Tribological behaviour of orthodontic archwires under dry and wet sliding conditions in-vitro. II--Wear patterns.

PubMed

Berradja, Abdenacer; Willems, Guy; Celis, Jean-Pierre

2006-05-01

To evaluate the wear patterns of orthodontic archwires in dry and wet conditions in-vitro. The patterns of wear of stainless steel and NiTi orthodontic archwires were investigated with a fretting wear tribometer fitted with an alumina ball. The tribometer was operated at 23 degrees C in three different environments: ambient air with 50 per cent relative humidity (RH), 0.9 wt. per cent sodium chloride solution and deionised water. Differences in the wear characteristics of the archwires were investigated by scanning electron microscopy. Energy Dispersive X-ray Analysis and Inductively Coupled Plasma Analysis were used to investigate the surface composition of the wires, the wear debris generated during fretting and the corrosion products in the test solutions. Both archwire materials were degraded by oxidational wear in ambient air. The NiTi wires were more resistant to wear than the stainless steel wires. In the aqueous media the stainless steel wires were degraded by abrasive wear, while the NiTi wires were degraded by adhesive wear. In ambient air with 50 per cent RH, NiTi wires were more resistant to wear than stainless steel wires. Both archwire materials exhibited higher wear rates in the solutions than in air, indicating some synergism between the wear and corrosion processes. In the solutions the stainless steel archwires had a much lower corrosion-wear resistance than the NiTi archwires.

Boundary Layer Flow Control with a One Atmosphere Uniform Glow Discharge Surface Plasma

NASA Technical Reports Server (NTRS)

Roth, J. Reece; Sherman, Daniel M.; Wilkinson, Stephen P.

1998-01-01

Low speed wind tunnel data have been acquired for planar panels covered by a uniform, glow-discharge surface plasma in atmospheric pressure air known as the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). Streamwise and spanwise arrays of flush, plasma-generating surface electrodes have been studied in laminar, transitional, and fully turbulent boundary layer flow. Plasma between symmetric streamwise electrode strips caused large increases in panel drag, whereas asymmetric spanwise electrode configurations produced a significant thrust. Smoke wire flow visualization and mean velocity diagnostics show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong paraelectric ElectroHydroDynamic (EHD) body forces on the flow.

Force Measurements on Plasma Actuators Using Phase-locked Particle Image Velocimetry

DTIC Science & Technology

2015-05-01

structured as follows. In Section 2, the details of the experimental apparatus and procedures, including the plasma actuator, the electronics used for...was placed ing the plasm wire gauge ( tage probe. l, which wa a ratio of 2 on signal wa he excitation ft) and the di DRDC-RDD on the force a...a Trek Mod t 2.5 kHz an e plasma cope (right). 1 a t el d DRDC F Durin using metho magn plasm -RDDC-2015 igure 4: Sche Figu g each exper the

Effect of sheath gas in atmospheric-pressure plasma jet for potato sprouting suppression

NASA Astrophysics Data System (ADS)

Nishiyama, S.; Monma, M.; Sasaki, K.

2016-09-01

Recently, low-temperature atmospheric-pressure plasma jets (APPJs) attract much interest for medical and agricultural applications. We try to apply APPJs for the suppression of potato sprouting in the long-term storage. In this study, we investigated the effect of sheath gas in APPJ on the suppression efficiency of the potato sprouting. Our APPJ was composed of an insulated thin wire electrode, a glass tube, a grounded electrode which was wound on the glass tube, and a sheath gas nozzle which was attached at the end of the glass tube. The wire electrode was connected to a rectangular-waveform power supply at a frequency of 3 kHz and a voltage of +/- 7 kV. Helium was fed through the glass tube, while we tested dry nitrogen, humid nitrogen, and oxygen as the sheath gas. Eyes of potatoes were irradiated by APPJ for 60 seconds. The sprouting probability was evaluated at two weeks after the plasma irradiation. The sprouting probability was 28% when we employed no sheath gases, whereas an improved probability of 10% was obtained when we applied dry nitrogen as the sheath gas. Optical emission spectroscopy was carried out to diagnose the plasma jet. It was suggested that reactive species originated from nitrogen worked for the efficient suppression of the potato sprouting.

Fast, Nonspattering Inert-Gas Welding

NASA Technical Reports Server (NTRS)

Gilbert, Jeffrey L.

1991-01-01

Proposed welding technique combines best features of metal (other than tungsten)/inert-gas welding, plasma arc welding, and tungsten/inert-gas welding. Advantages include: wire fed to weld joint preheated, therefore fed at high speed without spattering; high-frequency energy does not have to be supplied to workpiece to initiate welding; size of arc gap not critical, power-supply control circuit adjusts voltage across gap to compensate for changes; only low gas-flow rate needed; welding electrode replaced easily as prefabricated assembly; external wire-feeding manipulator not needed; and welding process relatively forgiving of operator error.

Semiconductor Nanorod–Carbon Nanotube Biomimetic Films for Wire-Free Photostimulation of Blind Retinas

PubMed Central

2014-01-01

We report the development of a semiconductor nanorod-carbon nanotube based platform for wire-free, light induced retina stimulation. A plasma polymerized acrylic acid midlayer was used to achieve covalent conjugation of semiconductor nanorods directly onto neuro-adhesive, three-dimensional carbon nanotube surfaces. Photocurrent, photovoltage, and fluorescence lifetime measurements validate efficient charge transfer between the nanorods and the carbon nanotube films. Successful stimulation of a light-insensitive chick retina suggests the potential use of this novel platform in future artificial retina applications. PMID:25350365

Sensor for detecting changes in magnetic fields

DOEpatents

Praeg, W.F.

1980-02-26

A sensor is described for detecting changes in the magnetic field of the equilibrium-field coil of a Tokamak plasma device that comprises a pair of bifilar wires disposed circumferentially, one inside and one outside the equilibrium-field coil. Each is shorted at one end. The difference between the voltages detected at the other ends of the bifilar wires provides a measure of changing flux in the equilibrium-field coil. This difference can be used to detect faults in the coil in time to take action to protect the coil.

The shear strength of three-dimensional capillary-porous titanium coatings for intraosseous implants.

PubMed

Kalita, V I; Komlev, D I; Komlev, V S; Radyuk, A A

2016-03-01

A plasma spraying process for the deposition of three-dimensional capillary-porous titanium coatings using a wire has been developed. In this process, two additional dc arcs are discharged between plasmatron and both the wire and the substrate, resulting in additional activation of the substrate and the particles, particularly by increasing their temperature. The shear strength of the titanium coating with 46% porosity is 120.6 MPa. A new procedure for estimating the shear strength of porous coatings has been developed. Copyright © 2015 Elsevier B.V. All rights reserved.

Nail-like targets for laser plasma interaction experiments

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

Pasley, J; Wei, M; Shipton, E

2007-12-18

The interaction of ultra-high power picosecond laser pulses with solid targets is of interest both for benchmarking the results of hybrid particle in cell (PIC) codes and also for applications to re-entrant cone guided fast ignition. We describe the construction of novel targets in which copper/titanium wires are formed into 'nail-like' objects by a process of melting and micromachining, so that energy can be reliably coupled to a 24 {micro}m diameter wire. An extreme-ultraviolet image of the interaction of the Titan laser with such a target is shown.

High Energy Electron Detectors on Sphinx

NASA Astrophysics Data System (ADS)

Thompson, J. R.; Porte, A.; Zucchini, F.; Calamy, H.; Auriel, G.; Coleman, P. L.; Bayol, F.; Lalle, B.; Krishnan, M.; Wilson, K.

2008-11-01

Z-pinch plasma radiation sources are used to dose test objects with K-shell (˜1-4keV) x-rays. The implosion physics can produce high energy electrons (> 50keV), which could distort interpretation of the soft x-ray effects. We describe the design and implementation of a diagnostic suite to characterize the electron environment of Al wire and Ar gas puff z-pinches on Sphinx. The design used ITS calculations to model detector response to both soft x-rays and electrons and help set upper bounds to the spurious electron flux. Strategies to discriminate between the known soft x-ray emission and the suspected electron flux will be discussed. H.Calamy et al, ``Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion,'' Phys Plasmas 15, 012701 (2008) J.A.Halbleib et al, ``ITS: the integrated TIGER series of electron/photon transport codes-Version 3.0,'' IEEE Trans on Nuclear Sci, 39, 1025 (1992)

Determination of plasma pinch time and effective current radius of double planar wire array implosions from current measurements on a 1-MA linear transformer driver

NASA Astrophysics Data System (ADS)

Steiner, Adam M.; Yager-Elorriaga, David A.; Patel, Sonal G.; Jordan, Nicholas M.; Gilgenbach, Ronald M.; Safronova, Alla S.; Kantsyrev, Victor L.; Shlyaptseva, Veronica V.; Shrestha, Ishor; Schmidt-Petersen, Maximillian T.

2016-10-01

Implosions of planar wire arrays were performed on the Michigan Accelerator for Inductive Z-pinch Experiments, a linear transformer driver (LTD) at the University of Michigan. These experiments were characterized by lower than expected peak currents and significantly longer risetimes compared to studies performed on higher impedance machines. A circuit analysis showed that the load inductance has a significant impact on the current output due to the comparatively low impedance of the driver; the long risetimes were also attributed to high variability in LTD switch closing times. A circuit model accounting for these effects was employed to measure changes in load inductance as a function of time to determine plasma pinch timing and calculate a minimum effective current-carrying radius. These calculations showed good agreement with available shadowgraphy and x-ray diode measurements.

Recent results of the Filippov-type PF experiments at Kurchatov Institute

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

Krauz, V. I.; Karakin, M. A.; Khautiev, E. Yu.

2006-01-15

The experiments with various plasma-producing substances performed recently were the main content at the PF-3 facility studies: (i) The dependence of the wire array compression on the number of wires was investigated with the deuterium as a filling gas. (ii) The neutron output, 5{center_dot}106 neutrons per shot, was registered in experiments with deuterium-polythene fibers when argon was used as a filling gas. Experimental confirmation of fibers pre-heating by radiation of the current sheath compressed to an axis was obtained. (iii) Studies of interaction of dense high-temperature plasma with the condensed disperse substance (dust) were continued. The dependence of the pinchmore » dynamics on the dust target parameters was investigated. In the shots with dust fraction of the fine-disperse Al2O3 powder, modes with increased pinch MHD-stability are found.« less

Unraveling the Complexities of the Upper Atmosphere as a System

NASA Astrophysics Data System (ADS)

Fuller-Rowell, T. J.

2016-12-01

The Earth's upper atmosphere responds as a system to external forcing from the Sun, magnetosphere, and lower atmosphere. The underlying system components comprise a highly dynamic, non-linear neutral fluid supporting fast propagating wave fields, advective transport, dissipation, and chemical changes, coupled to an active plasma constrained by all-encompassing magnetic and electric fields. More importantly, the plasma and more massive neutral gas are intimately coupled. Ion-neutral coupling can drive winds ten-times hurricane strength making inertia a dominant force; it can sometimes wipe out 90% of the plasma, and at other times allow plasma content to explode with dangerous consequences. Ion-neutral dissipation can result in intense heating, allowing the atmosphere to expand to double its normal size, dragging Earth orbiting satellites to the ground. The thermospheric dynamo, ultimately driven by the solar and magnetosphere dynamos, redistributes equatorial plasma and can drive structure, steep gradients, and irregularities. A single satellite sampling the medium is suitable for uncovering perhaps one or two of the many interacting processes, in what could be called discovery mode science. Without a three-dimensional imaging capability, a single satellite cannot explore the interaction and balance between the multiple of processes actually present. Unraveling the system-wide or global response requires multi-point in-situ constellation-type measurements, together with available two-dimensional imaging. Modeling the system can create an illusion of understanding, but until we really look we will never know.

All That Remains of Exploded Star

NASA Image and Video Library

2011-10-24

Infrared images from NASA Spitzer Space Telescope and Wide-field Infrared Survey Explorer are combined in this image of RCW 86, the dusty remains of the oldest documented example of an exploding star, or supernova.

A new structure of superconducting magnetic system for 50 GHz operations (invited).

PubMed

Xie, D Z

2012-02-01

High field and high frequency have been leading the development of electron cyclotron resonance ion sources (ECRISs) in the past decade as demonstrated by the achieved great performance. The present superconducting magnet structures built with NbTi wires have reached an axial field of 3.5-4.0 T and a radial field of 2.0 T for operating frequency up to 28 GHz. Further increase of the magnetic field strength will require higher current superconductor, i.e., Nb(3)Sn wires. This paper will present the features of a new superconducting magnet structure and review of the existing structures. Using NbTi wires, the new magnet structure could be able to produce maximum fields of 7.0 T on axis and radial field of 3.7 T at a hexagonal plasma chamber wall for ECRIS operations up to 50 GHz. If this new magnet can be built with Nb(3)Sn wires, much higher fields can be expected.

Measuring the dynamic polarizability of tungsten atom via electrical wire explosion in vacuum

NASA Astrophysics Data System (ADS)

Shi, Huantong; Zou, Xiaobing; Wang, Xinxin

2018-02-01

Electrical explosion of wire provides a practical approach to the experimental measurement of dynamic polarizability of metal atoms with high melting and boiling temperatures. With the help of insulation coating, a section of tungsten wire was transformed to the plasma state while the near electrode region was partially vaporized, which enabled us to locate the "neutral-region" (consisting of gaseous atoms) in the Mach-Zehnder interferogram. In this paper, the polarizability of the tungsten atom at 532 nm was reconstructed based on a technique previously used for the same purpose, and the basic preconditions of the measurement were verified in detail, including the existence of the neutral region, conservation of linear density of tungsten during wire expansion, and neglect of the vaporized insulation coating. The typical imaging time varied from 80 ns to as late as 200 ns and the reconstructed polarizability of the tungsten atom was 16 ± 1 Å3, which showed good statistical consistency and was also in good agreement with the previous results.

Lifetime Extension of the Gas Discharge Detectors with Plasma Etching of Silicon Deposits in 80%CF4 + 20%CO2

NASA Astrophysics Data System (ADS)

Gavrilov, G. E.; Vakhtel, V. M.; Maysuzenko, D. A.; Tavtorkina, T. A.; Fetisov, A. A.; Shvetsova, N. Yu.

2017-12-01

A method of elimination of silicon compounds from the anode wire of an aged proportional counter is presented. The aging of a counter with a 70%Ar + 30%CO2 and a 60%Ar + 30%CO2 + 10%CF4 working mixture was stimulated by a 90Sr β source. To accelerate the process of aging, the gas mixture flow to the counter was supplied through a pipe with RTV coated wall. As a result, the amplitude of the signal decreased 70% already at accumulated charge of Q = 0.03 C/cm. The etching of the silicon compounds on the wire surface with an 80%CF4 + 20%CO2 gas mixture discharge led to full recovery of the operating characteristics of detector and an increase in the lifetime. A scanning electron microscopy and X-ray spectroscopy analysis of the recovered wire surface were performed. In accordance with the results, a good quality of wire cleaning from SiO2 compounds was obtained.

Characterization of explosive devices in luggage: Initial results of the ART-IIC test series

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

Akerman, M.A.; Kass, M.D.; Clough, B.T.

1993-12-31

Characteristics and damage associated with exploded luggage aboard aircraft are presented in this paper. Plastic-sided suitcases filled with typical travel possessions were exploded inside the fuselage of decomissioned B-52 aircraft. Multilayered shield panels, mounted to one side of the fuselage, served to protect the aircraft body and flight system components from both the blast wave and exploded fragments. The resulting damage produced by the explosions was characterized and the absorbing characteristics of the shielding were evaluated. In addition, the energy of the luggage fragments was estimated.

Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches

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

Swadling, G. F.; Lebedev, S. V.; Niasse, N.

A series of experiments has been conducted in order to investigate the azimuthal structures formed by the interactions of cylindrically converging plasma flows during the ablation phase of aluminium wire array Z pinch implosions. These experiments were carried out using the 1.4 MA, 240 ns MAGPIE generator at Imperial College London. The main diagnostic used in this study was a two-colour, end-on, Mach-Zehnder imaging interferometer, sensitive to the axially integrated electron density of the plasma. The data collected in these experiments reveal the strongly collisional dynamics of the aluminium ablation streams. The structure of the flows is dominated by amore » dense network of oblique shock fronts, formed by supersonic collisions between adjacent ablation streams. An estimate for the range of the flow Mach number (M = 6.2-9.2) has been made based on an analysis of the observed shock geometry. Combining this measurement with previously published Thomson Scattering measurements of the plasma flow velocity by Harvey-Thompson et al.[Physics of Plasmas 19, 056303 (2012)] allowed us to place limits on the range of the ZT{sub e} of the plasma. The detailed and quantitative nature of the dataset lends itself well as a source for model validation and code verification exercises, as the exact shock geometry is sensitive to many of the plasma parameters. Comparison of electron density data produced through numerical modelling with the Gorgon 3D MHD code demonstrates that the code is able to reproduce the collisional dynamics observed in aluminium arrays reasonably well.« less

Characterization of a microwave-excited atmospheric-pressure argon plasma jet using two-parallel-wires transmission line resonator

NASA Astrophysics Data System (ADS)

Choi, J.; Eom, I. S.; Kim, S. J.; Kwon, Y. W.; Joh, H. M.; Jeong, B. S.; Chung, T. H.

2017-09-01

This paper presents a method to produce a microwave-excited atmospheric-pressure plasma jet (ME-APPJ) with argon. The plasma was generated by a microwave-driven micro-plasma source that uses a two-parallel-wire transmission line resonator (TPWR) operating at around 900 MHz. The TPWR has a simple structure and is easier to fabricate than coaxial transmission line resonator (CTLR) devices. In particular, the TPWR can sustain more stable ME-APPJ than the CTLR can because the gap between the electrodes is narrower than that in the CTLR. In experiments performed with an Ar flow rate from 0.5 to 8.0 L.min-1 and an input power from 1 to 6 W, the rotational temperature was determined by comparing the measured and simulated spectra of rotational lines of the OH band and the electron excitation temperature determined by the Boltzmann plot method. The rotational temperature obtained from OH(A-X) spectra was 700 K to 800 K, whereas the apparent gas temperature of the plasma jet remains lower than ˜325 K, which is compatible with biomedical applications. The electron number density was determined using the method based on the Stark broadening of the hydrogen Hβ line, and the measured electron density ranged from 6.5 × 1014 to 7.6 × 1014 cm-3. TPWR ME-APPJ can be operated at low flows of the working gas and at low power and is very stable and effective for interactions of the plasma with cells.

Converging shock wave focusing and interaction with a target

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

Nitishinskiy, M.; Efimov, S.; Antonov, O.

2016-04-15

Converging shock waves in liquids can be used efficiently in the research of the extreme state of matter and in various applications. In this paper, the recent results related to the interaction of a shock wave with plasma preliminarily formed in the vicinity of the shock wave convergence are presented. The shock wave is produced by the underwater electrical explosion of a spherical wire array. The plasma is generated prior to the shock wave's arrival by a low-pressure gas discharge inside a quartz capillary placed at the equatorial plane of the array. Analysis of the Stark broadening of H{sub α}more » and H{sub β} spectral lines and line-to-continuum ratio, combined with the ratio of the relative intensities of carbon C III/C II and silicon Si III/Si II lines, were used to determine the plasma density and temperature evolution. It was found that during the first ∼200 ns with respect to the beginning of the plasma compression by the shock wave and when the spectral lines are resolved, the plasma density increases from 2 × 10{sup 17 }cm{sup −3} to 5 × 10{sup 17 }cm{sup −3}, while the temperature remains at the same value of 3–4 eV. Further, following the model of an adiabatically imploding capillary, the plasma density increases >10{sup 19 }cm{sup −3}, leading to the continuum spectra obtained experimentally, and the plasma temperature >30 eV at radii of compression of ≤20 μm. The data obtained indicate that the shock wave generated by the underwater electrical explosion of a spherical wire array retains its uniformity during the main part of its convergence.« less

Implosion dynamics of a megampere wire-array Z-pinch with an inner low-density foam shell at the Angara-5-1 facility

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

Aleksandrov, V. V.; Bolkhovitinov, E. A.; Volkov, G. S., E-mail: volkov@triniti.ru

The implosion dynamics of a pinch with a highly inhomogeneous initial axial distribution of the load mass was studied experimentally. A cascade array consisting of a double nested tungsten wire array and a coaxial inner cylindrical shell located symmetrically with respect to the high-voltage electrodes was used as a load of the Angara-5-1 high-current generator. The cylindrical foam shell was half as long as the cathode− anode gap, and its diameter was equal to the diameter of the inner wire array. It is shown experimentally that two stages are typical of the implosion dynamics of such a load: the formationmore » of two separate pinches formed as a result of implosion of the wire array near the cathode and anode and the subsequent implosion of the central part of the load containing the cylindrical foam shell. The conditions are determined at which the implosion of the central part of the pinch with the foam cylinder is preceded by intense irradiation of the foam with the soft X-ray (SXR) emission generated by the near-electrode pinches and converting it into the plasma state. Using such a load, which models the main elements of the scheme of a dynamic hohlraum for inertial confinement fusion, it is possible to increase the efficiency of interaction between the outer accelerated plasma sheath and the inner foam shell by preionizing the foam with the SXR emission of the near-electrode pinches.« less

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

Rodenbeck, Christopher T; Girardi, Michael

Internal nodes of a constituent integrated circuit (IC) package of a multichip module (MCM) are protected from excessive charge during plasma cleaning of the MCM. The protected nodes are coupled to an internal common node of the IC package by respectively associated discharge paths. The common node is connected to a bond pad of the IC package. During MCM assembly, and before plasma cleaning, this bond pad receives a wire bond to a ground bond pad on the MCM substrate.

Pulsed Corona Discharge Generated By Marx Generator

NASA Astrophysics Data System (ADS)

Sretenovic, G. B.; Obradovic, B. M.; Kovacevic, V. V.; Kuraica, M. M.; Puric J.

2010-07-01

The pulsed plasma has a significant role in new environmental protection technologies. As a part of a pulsed corona system for pollution control applications, Marx type repetitive pulse generator was constructed and tested in arrangement with wire-plate corona reactor. We performed electrical measurements, and obtained voltage and current signals, and also power and energy delivered per pulse. Ozone formation by streamer plasma in air was chosen to monitor chemical activity of the pulsed corona discharge.

Teaching Chemistry through Observation--The Exploding Can Demonstration.

ERIC Educational Resources Information Center

Golestaneh, Kamran

1998-01-01

Describes procedures for a demonstration that features an exploding can. This demonstration prompts students to critically analyze the release of energy in an exothermic reaction, the work done in such a reaction, and the enthalpy. (DDR)

Flame Deflector Section, Elevation, Water Supply Flow Diagram, Exploded ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Flame Deflector - Section, Elevation, Water Supply Flow Diagram, Exploded Deflector Manifolds, and Interior Perspective - Marshall Space Flight Center, F-1 Engine Static Test Stand, On Route 565 between Huntsville and Decatur, Huntsville, Madison County, AL

Imposed, ordered dust structures and other plasma features in a strongly magnetized plasma

NASA Astrophysics Data System (ADS)

Thomas, Edward; Leblanc, Spencer; Lynch, Brian; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene

2015-11-01

The Magnetized Dusty Plasma Experiment (MDPX) device has been in operation for just over one year. In that time, the MDPX device has been operating using a uniform magnetic field configuration up to 3.0 Tesla and has successfully produced plasmas and dusty plasmas at high magnetic fields. In these experimental studies, we have made observations of a new type of imposed, ordered structure in a dusty plasma at magnetic fields above 1 T. These dusty plasma structures are shown to scale inversely with neutral pressure and are shown to reflect the spatial structure of a wire mesh placed in the plasma. Additionally, recent measurements have been made that give insights into the effective potential that establishes the ordered structures in the plasma. In this presentation, we report on details of the imposed, ordered dusty plasma structure as well as filamentary features that also appear in the plasma and modify the confinement of the dusty plasma. This work is supported with funding from the NSF and Department of Energy.

Evaluation of Pd-Cr Wires for Strain Gage Application

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Greer, L. C., III; Oberle, L. G.

1995-01-01

A newly developed alloy, palladium-13 weight percent chromium (Pd13Cr), was identified by United Technologies Research Center under a NASA contract to be the best material for high temperature strain gage applications. An electrical resistance strain gage that can provide accurate static strain measurement to a temperature higher than that of a commercially available gage is urgently needed in aerospace and aeronautics research. A strain gage made of a 25.4 micron (1 mil) diameter Pd13Cr wire has been recently demonstrated to be usable for static strain measurements to 800 C. This compares to the 400 C temperature limit of the commercially available strain gages. The performance of the Pd-Cr gage, however, strongly depends on the quality of the Pd13Cr wire. Four batches of Pd-Cr wires purchased from three different manufacturers were therefore evaluated to determine the best source of the wire for strain gage applications. The three suppliers were Precious Metal Institute in China, Sigmund Cohn Co., and G & S Titanium, Inc. in the United States. Two batches of wires obtained from Previous Metal Institute in 1987 and 1992, respectively are referred to herein as China87 and China92 wires. The mechanical, chemical and electrical properties of these wires, both as-received and after high temperature exposures at 800 C for 50 hours were analyzed. The elastic modulus and the failure strength of the wires were evaluated using a tensile test machine equipped with a laser speckle strain measurement system. The chemical and microstructural properties of the wires were inspected using a plasma atomic emission spectrometer and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscope (EDS). The electrical stability and repeatability of the wires were determined by measuring the electrical resistance of the wires during three thermal cycles to 1000 C and a ten-hour soak at 1000 C. As a result of this study, the wire which has the highest strength, the least impurities content, the best oxidation resistance and the best electrical stability will be selected for upcoming strain gage applications.

2D and 3D Simulations of Exploding Pusher Capsules

NASA Astrophysics Data System (ADS)

Pino, Jesse; Smith, Andrew; Miles, Aaron

2011-10-01

A research campaign is underway at the National Ignition Facility (NIF) at LLNL to study rapidly evolving, non-LTE, inertial fusion plasmas. The goal is to field thin-shelled, gas filled ``Exploding Pusher'' capsules in a Polar Direct Drive (PDD) configuration. Ion temperatures of > 15 keV and electron temperatures of > 5 keV are reached. A small convergence ratio and rapidly ablated shell reduce susceptibility to hydrodynamic instabilities. Using 1D simulations, most favorable configurations were found to be thin SiO2 or Be shells containing 10 atm of D2-He3 in a 2:1 ratio. This poster describes the 2D and 3D ARES Radiation Hydrodynamics simulations of these capsules. 2D simulations are essential because the PDD configuration requires that each of the beams be ``repointed'' away from their nominal angles. Each beam can also have a separate power profile and focal length. Large ensembles of simulations were run to probe the parameter space and find the optimal pointing resulting in the most spherical implosions. Response surfaces were constructed to ascertain the susceptibility to shot-time fluctuations. We also discuss resolution convergence and present preliminary results of 3D modeling. This work performed under the auspices of the U.S. DoE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Galvanic corrosion between orthodontic wires and brackets in fluoride mouthwashes.

PubMed

Schiff, Nicolas; Boinet, Mickaël; Morgon, Laurent; Lissac, Michèle; Dalard, Francis; Grosgogeat, Brigitte

2006-06-01

The aim of this investigation was to determine the influence of fluoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution of Fusayama-Meyer artificial saliva and in two commercially available fluoride (250 ppm) mouthwashes, Elmex and Meridol. Corrosion resistance was assessed by inductively coupled plasma-atomic emission spectrometry (ICP-MS), analysis of released metal ions, and a scanning electron microscope (SEM) study of the metal surfaces after immersion of different wire-bracket pairs in the test solutions. The study was completed by an electrochemical analysis. Meridol mouthwash, which contains stannous fluoride, was the solution in which the NiTi wires coupled with the different brackets showed the highest corrosion risk, while in Elmex mouthwash, which contains sodium fluoride, the CuNiTi wires presented the highest corrosion risk. Such corrosion has two consequences: deterioration in mechanical performance of the wire-bracket system, which would negatively affect the final aesthetic result, and the risk of local allergic reactions caused by released Ni ions. The results suggest that mouthwashes should be prescribed according to the orthodontic materials used. A new type of mouthwash for use during orthodontic therapy could be an interesting development in this field.

A Probability Problem from Real Life: The Tire Exploded.

ERIC Educational Resources Information Center

Bartlett, Albert A.

1993-01-01

Discusses the probability of seeing a tire explode or disintegrate while traveling down the highway. Suggests that a person observing 10 hours a day would see a failure on the average of once every 300 years. (MVL)

Sounding experiments of high pressure gas discharge

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

Biele, Joachim K.

A high pressure discharge experiment (200 MPa, 5{center_dot}10{sup 21} molecules/cm{sup 3}, 3000 K) has been set up to study electrically induced shock waves. The apparatus consists of the combustion chamber (4.2 cm{sup 3}) to produce high pressure gas by burning solid propellant grains to fill the electrical pump chamber (2.5 cm{sup 3}) containing an insulated coaxial electrode. Electrical pump energy up to 7.8 kJ at 10 kV, which is roughly three times of the gas energy in the pump chamber, was delivered by a capacitor bank. From the current-voltage relationship the discharge develops at rapidly decreasing voltage. Pressure at themore » combustion chamber indicating significant underpressure as well as overpressure peaks is followed by an increase of static pressure level. These data are not yet completely understood. However, Lorentz forces are believed to generate pinching with subsequent pinch heating, resulting in fast pressure variations to be propagated as rarefaction and shock waves, respectively. Utilizing pure axisymmetric electrode initiation rather than often used exploding wire technology in the pump chamber, repeatable experiments were achieved.« less

Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

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

Calamy, H.; Hamann, F.; Lassalle, F.

Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1{mu}s rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim ofmore » giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-{theta} simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.« less

Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

NASA Astrophysics Data System (ADS)

Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J. P.; Chittenden, J. P.; Lebedev, S. V.; Jennings, C. A.; Bland, S. N.

2006-01-01

Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1μs rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-θ simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

Hard X-ray and Particle Beams Research on 1.7 MA Z-pinch and Laser Plasma Experiments

NASA Astrophysics Data System (ADS)

Shrestha, Ishor; Kantsyrev, Victor; Safronova, Alla; Esaulov, Andrey; Nishio, Mineyuki; Shlyaptseva, Veronica; Keim, Steven; Weller, Michael; Stafford, Austin; Petkov, Emil; Schultz, Kimberly; Cooper, Matthew; PPDL Team

2013-10-01

Studies of hard x-ray (HXR) emission, electron and ion beam generation in z-pinch and laser plasmas are important for Inertial Confinement Fusion (ICF) and development of HXR sources from K-shell and L-shell radiation. The characteristics of HXR and particle beams produced by implosions of planar wire arrays, nested and single cylindrical wire arrays, and X-pinches were analyzed on 100 ns UNR Zebra generator with current up to 1.7 MA. In addition, the comparison of characteristics of HXR and electron beams on Zebra and 350 fs UNR Leopard laser experiments with foils has been performed. The diagnostics include Faraday cups, HXR diodes, different x-ray spectrometers and imaging systems, and ion mass spectrometer using the technique of Thomson parabola. Future work on HXRs and particle beams in HED plasmas is discussed. This work was supported by the DOE/NNSA Cooperative agreement DE-NA0001984 and in part by DE-FC52-06NA27616. This work was also supported by the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-13-1-0033, to University of Nevada, Reno.

A Cost-Effective Energy-Recovering Sustain Driving Circuit for ac Plasma Display Panels

NASA Astrophysics Data System (ADS)

Lim, Jae Kwang; Tae, Heung-Sik; Choi, Byungcho; Kim, Seok Gi

A new sustain driving circuit, featuring an energy-recovering function with simple structure and minimal component count, is proposed as a cost-effective solution for driving plasma display panels during the sustaining period. Compared with existing solutions, the proposed circuit reduces the number of semiconductor switches and reactive circuit components without compromising the circuit performance and gas-discharging characteristics. In addition, the proposed circuit utilizes the harness wire as an inductive circuit component, thereby further simplifying the circuit structure. The performance of the proposed circuit is confirmed with a 42-inch plasma display panel.

Textile inspired flexible metamaterial with negative refractive index

NASA Astrophysics Data System (ADS)

Burgnies, L.; Lheurette, É.; Lippens, D.

2015-04-01

This work introduces metallo-dielectric woven fabric as a metamaterial for phase-front manipulation. Dispersion diagram as well as effective medium parameters retrieved from reflection and transmission coefficients point out negative values of refractive index. By numerical simulations, it is evidenced that a pair of meandered metallic wires, arranged in a top to bottom configuration, can yield to a textile metamaterial with simultaneously negative permittivity and permeability. While the effective negative permittivity stems from the metallic grid arrangement, resonating current loop resulting from the top to bottom configuration of two meandered metallic wires in near proximity produces magnetic activity with negative permeability. By adjusting the distance between pairs of metallic wires, the electric plasma frequency can be shifted to overlap the magnetic resonance. Finally, it is shown that the woven metamaterial is insensitive to the incident angle up to around 60°.

A final report to the Laboratory Directed Research and Development committee on Project 93-ERP-075: ``X-ray laser propagation and coherence: Diagnosing fast-evolving, high-density laser plasmas using X-ray lasers``

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

Wan, A.S.; Cauble, R.; Da Silva, L.B.

1996-02-01

This report summarizes the major accomplishments of this three-year Laboratory Directed Research and Development (LDRD) Exploratory Research Project (ERP) entitled ``X-ray Laser Propagation and Coherence: Diagnosing Fast-evolving, High-density Laser Plasmas Using X-ray Lasers,`` tracking code 93-ERP-075. The most significant accomplishment of this project is the demonstration of a new laser plasma diagnostic: a soft x-ray Mach-Zehnder interferometer using a neonlike yttrium x-ray laser at 155 {angstrom} as the probe source. Detailed comparisons of absolute two-dimensional electron density profiles obtained from soft x-ray laser interferograms and profiles obtained from radiation hydrodynamics codes, such as LASNEX, will allow us to validate andmore » benchmark complex numerical models used to study the physics of laser-plasma interactions. Thus the development of soft x-ray interferometry technique provides a mechanism to probe the deficiencies of the numerical models and is an important tool for, the high-energy density physics and science-based stockpile stewardship programs. The authors have used the soft x-ray interferometer to study a number of high-density, fast evolving, laser-produced plasmas, such as the dynamics of exploding foils and colliding plasmas. They are pursuing the application of the soft x-ray interferometer to study ICF-relevant plasmas, such as capsules and hohlraums, on the Nova 10-beam facility. They have also studied the development of enhanced-coherence, shorter-pulse-duration, and high-brightness x-ray lasers. The utilization of improved x-ray laser sources can ultimately enable them to obtain three-dimensional holographic images of laser-produced plasmas.« less

Initial Development of an Exploding Aerosol Can Simulator

DOT National Transportation Integrated Search

1998-04-01

A device was constructed to simulate an exploding aerosol can. The device consisted of a cylindrical pressure vessel for storage of flammable propellants and base product and a high-rate discharge (HRD) valve for quick release of the constituents. Si...

LOFT. "Exploded view" of loft containment building (TAN650), including control ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

LOFT. "Exploded view" of loft containment building (TAN-650), including control building (TAN-630). EG&G. February 1979. INEEL index code no. 036-010-65-220-209565 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

Exploding and Imaging of Electron Bubbles in Liquid Helium

NASA Astrophysics Data System (ADS)

Yadav, Neha; Vadakkumbatt, Vaisakh; Maris, Humphrey J.; Ghosh, Ambarish

2017-06-01

An electron bubble in liquid helium-4 under the saturated vapor pressure becomes unstable and explodes if the pressure becomes more negative than -1.9 bars. In this paper, we use focused ultrasound to explode electron bubbles. We then image at 30,000 frames per second the growth and subsequent collapse of the bubbles. We find that bubbles can grow to as large as 1 mm in diameter within 2 ms after the cavitation event. We examine the relation between the maximum size of the bubble and the lifetime and find good agreement with the experimental results.

Effect of poultry litter biochar on Saccharomyces cerevisiae growth and ethanol production from steam-exploded poplar and corn stover

NASA Astrophysics Data System (ADS)

Diallo, Oumou

The use of ethanol produced from lignocellulosic biomass for transportation fuel offers solutions in reducing environmental emission and the use of non-renewable fuels. However, lignocellulosic ethanol production is still hampered by economic and technical obstacles. For instance, the inhibitory effect of toxic compounds produced during biomass pretreatment was reported to inhibit the fermenting microorganisms, hence there was a decrease in ethanol yield and productivity. Thus, there is a need to improve the bioconversion of lignocellulosic biomass to ethanol in order to promote its commercialization. The research reported here investigated the use of poultry litter biochar to improve the ethanol production from steam-exploded poplar and corn stover. The effect of poultry litter biochar was first studied on Saccharomyces cerevisiae ATCC 204508/S288C growth, and second on the enzyme hydrolysis and fermentation of two steam-exploded biomasses: (poplar and corn stover). The third part of the study investigated optimal process parameters (biochar loading, biomass loading, and enzyme loading) on the reducing sugars production, and ethanol yield from steam-exploded corn stover. In this study, it has been shown that poultry litter biochar improved the S. cerevisiae growth and ethanol productivity; therefore poultry litter biochar could potentially be used to improve the ethanol production from steam-exploded lignocellulosic biomass.

Synthesis of Pt nanoparticles as catalysts of oxygen reduction with microbubble-assisted low-voltage and low-frequency solution plasma processing

NASA Astrophysics Data System (ADS)

Horiguchi, Genki; Chikaoka, Yu; Shiroishi, Hidenobu; Kosaka, Shinpei; Saito, Morihiro; Kameta, Naohiro; Matsuda, Naoki

2018-04-01

In the preparation of metallic nanoparticles by conventional solution plasma (SP) techniques, unstable plasma emission becomes an issue when the voltage and frequency of the waves applied between two electrodes placed in solution are lowered to avoid the boiling of the solution. In this study, we confirm that, in the presence of microbubbles, plasma is generated stably at low voltage (440 V) and low frequency (50-100 Hz) and small-size (≤10 nm) Pt nanoparticles (PtNPs) are synthesized in succession using a flow cell. The smallest PtNPs, ∼3.3 nm in diameter, are obtained using half-wave rectification, a tungsten wire anode, and a platinum wire cathode. The PtNPs are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimeter-differential thermal analysis. The oxygen reduction reaction (ORR) is investigated in 0.1 M HClO4 solution on carbon-supported PtNPs using a rotating ring-disk electrode. The catalytic activities per initial electrochemical active surface area of the carbon-supported PtNPs synthesized employing the low-voltage, low-frequency (LVLF)-SP technique is higher than that of the commercially available 20 wt% Pt on Vulcan XC-72R. These results indicate that the LVLF-SP technique is a promising approach to producing carbon-supported PtNPs that catalyze ORR with low energy consumption.

Microstructure and Mechanical Properties of Plasma Arc Brazed AISI 304L Stainless Steel and Galvanized Steel Plates

NASA Astrophysics Data System (ADS)

Jin, Yajuan; Li, Ruifeng; Yu, Zhishui; Wang, Yu

2016-04-01

Plasma arc brazing is used to join the AISI 304L stainless steel and galvanized steel plate butt joints with the CuSi3Mn1 filler wire. The effect of parameters on weld surface appearance, interfacial microstructure, and composition distribution in the joint was studied. The microhardness and mechanical tests were conducted to determine the mechanical properties of the welded specimens. The results indicated that good appearance, bead shape, and sufficient metallurgical bonding could be obtained when the brazing process was performed with a wire feeding speed of 0.8 m/min, plasma gas flow rate of 3.0 l/min, welding current of 100 A, and welding speed of 27 cm/min. During plasma arc brazing process, the top corner of the stainless steel and galvanized steel plate were heated and melted, and the melted quantity of stainless steel was much more than that of the galvanized steel due to the thermal conductivity coefficient difference between the dissimilar materials. The microhardness test results shows that the microhardness value gradually increased from the side of the galvanized steel to the stainless steel in the joint, and it is good for improving the mechanical properties of joint. The tensile strength was a little higher than that of the brazing filler, and the fracture position of weld joint was at the base metal of galvanized steel plate.

Current scaling of radiated power for 40-mm diameter single wire arrays on Z

NASA Astrophysics Data System (ADS)

Nash, T. J.; Cuneo, M. E.; Spielman, R. B.; Chandler, G. A.; Leeper, R. J.; Seaman, J. F.; McGurn, J.; Lazier, S.; Torres, J.; Jobe, D.; Gilliland, T.; Nielsen, D.; Hawn, R.; Bailey, J. E.; Lake, P.; Carlson, A. L.; Seamen, H.; Moore, T.; Smelser, R.; Pyle, J.; Wagoner, T. C.; LePell, P. D.; Deeney, C.; Douglas, M. R.; McDaniel, D.; Struve, K.; Mazarakis, M.; Stygar, W. A.

2004-11-01

In order to estimate the radiated power that can be expected from the next-generation Z-pinch driver such as ZR at 28 MA, current-scaling experiments have been conducted on the 20 MA driver Z. We report on the current scaling of single 40 mm diameter tungsten 240 wire arrays with a fixed 110 ns implosion time. The wire diameter is decreased in proportion to the load current. Reducing the charge voltage on the Marx banks reduces the load current. On one shot, firing only three of the four levels of the Z machine further reduced the load current. The radiated energy scaled as the current squared as expected but the radiated power scaled as the current to the 3.52±0.42 power due to increased x-ray pulse width at lower current. As the current is reduced, the rise time of the x-ray pulse increases and at the lowest current value of 10.4 MA, a shoulder appears on the leading edge of the x-ray pulse. In order to determine the nature of the plasma producing the leading edge of the x-ray pulse at low currents further shots were taken with an on-axis aperture to view on-axis precursor plasma. This aperture appeared to perturb the pinch in a favorable manner such that with the aperture in place there was no leading edge to the x-ray pulses at lower currents and the radiated power scaled as the current squared ±0.75. For a full-current shot we will present x-ray images that show precursor plasma emitting on-axis 77 ns before the main x-ray burst.

Investigation of trailing mass in Z-pinch implosions and comparison to experiment

NASA Astrophysics Data System (ADS)

Yu, Edmund

2007-11-01

Wire-array Z pinches represent efficient, high-power x-ray sources with application to inertial confinement fusion, high energy density plasmas, and laboratory astrophysics. The first stage of a wire-array Z pinch is described by a mass ablation phase, during which stationary wires cook off material, which is then accelerated radially inwards by the JxB force. The mass injection rate varies axially and azimuthally, so that once the ablation phase concludes, the subsequent implosion is highly 3D in nature. In particular, a network of trailing mass and current is left behind the imploding plasma sheath, which can significantly affect pinch performance. In this work we focus on the implosion phase, electing to model the mass ablation via a mass injection scheme. Such a scheme has a number of injection parameters, but this freedom also allows us to gain understanding into the nature of the trailing mass network. For instance, a new result illustrates the role of azimuthal correlation. For an implosion which is 100% azimuthally correlated (corresponding to an azimuthally symmetric 2D r-z problem), current is forced to flow on the imploding plasma sheath, resulting in strong Rayleigh-Taylor (RT) growth. If, however, the implosion is not azimuthally symmetric, the additional azimuthal degree of freedom opens up new conducting paths of lower magnetic energy through the trailing mass network, effectively reducing RT growth. Consequently the 3D implosion experiences lower RT growth than the 2D r-z equivalent, and actually results in a more shell-like implosion. A second major goal of this work is to constrain the injection parameters by comparison to a well-diagnosed experimental data set, in which array mass was varied. In collaboration with R. Lemke, M. Desjarlais, M. Cuneo, C. Jennings, D. Sinars, E. Waisman

Method for Cleaning Laser-Drilled Holes on Printed Wiring Boards by Plasma Treatment

NASA Astrophysics Data System (ADS)

Hirogaki, Toshiki; Aoyama, Eiichi; Minagi, Ryu; Ogawa, Keiji; Katayama, Tsutao; Matsuoka, Takashi; Inoue, Hisahiro

We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

Diagnosis of a two wire X-pinch by X-ray absorption spectroscopy utilizing a doubly curved ellipsoidal crystal

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

Cahill, A. D., E-mail: adc87@cornell.edu; Hoyt, C. L., E-mail: adc87@cornell.edu; Shelkovenko, T. A., E-mail: adc87@cornell.edu

2014-12-15

X-ray absorption spectroscopy is a powerful tool for the diagnosis of plasmas over a wide range of both temperature and density. However, such a measurement is often limited to probing plasmas with temperatures well below that of the x-ray source in order to avoid object plasma emission lines from obscuring important features of the absorption spectrum. This has excluded many plasmas from being investigated by this technique. We have developed an x-ray spectrometer that provides the ability to record absorption spectra from higher temperature plasmas than the usual approach allows without the risk of data contamination by line radiation emittedmore » by the plasma under study. This is accomplished using a doubly curved mica crystal which is bent both elliptically and cylindrically. We present here initial absorption spectra obtained from an aluminum x-pinch plasma.« less

Computer Simulation of Magnetic Nova Shell Expantion

NASA Astrophysics Data System (ADS)

Dudnikova, Galina; Nikitin, Sergei; Snytnikov, Valeri; Vshivkov, Vitali

2000-10-01

An asymmetrical character of the shell expantion observed at many Nova may be associated with infuence of an inherent star magnetic field. Magneto-dipole energy of a Nova is much less than a kinetic energy of an exploding envelope. By this reason the conventional hydrodynamic models of point-like explosion with a spherical outward-directed shock wave do not consider effect of star magnetic field on the plasma movement. We used the numerical model based on the system of equations of the hybrid type( MHD approximation for electrons and Vlasov kinetic equations for ions). PIC-method for solving Vlasov equations was used. It gives an opportunaty to consider a complicated multi-flow motion of particles in plasma at super-Alfven velocity. At the beginning there is an immobile (cold) background plasma of a homogeneous concentration in a cylindrical region with a dipole magnetic field. Into the central spherical region of radius R, where the magnetic field remains uniform and constant , the external plasma does not penetrate with elastic reflections of ions at the spherical core surface. This boundary is spaced at r<

Effects of furan derivatives on biohydrogen fermentation from wet steam-exploded cornstalk and its microbial community.

PubMed

Liu, Zhidan; Zhang, Chong; Wang, Linjun; He, Jianwei; Li, Baoming; Zhang, Yuanhui; Xing, Xin-Hui

2015-01-01

Understanding the role of furan derivatives, furfural (FUR) and 5-hydroxymethyl furfural (HMF), is important for biofuel production from lignocellulosic biomass. In this study, the effects of furan derivatives on hydrogen fermentation from wet steam-exploded cornstalk were investigated. The control experiments with only seed sludge indicated that HMF addition of up to 1g/L stimulated hydrogen production. Similar results were obtained using steam-exploded cornstalk as the feedstock. Hydrogen productivity was increased by up to 40% with the addition of HMF. In addition, over 90% of furan derivatives with an initial concentration below 1g/L were degraded. Pyosequencing showed that the addition of HMF and FUR resulted in different microbial communities. HMF led to a higher proportion of the genera Clostridium and Ruminococcaceae, supporting the increased hydrogen production. This study suggested that hydrogen fermentation could be a detoxifying step for steam-exploded cornstalk, and HMF and FUR exhibited different functions for hydrogen fermentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Numerical simulation of exploding pusher targets

NASA Astrophysics Data System (ADS)

Atzeni, S.; Rosenberg, M. J.; Gatu Johnson, M.; Petrasso, R. D.

2017-10-01

Exploding pusher targets, i.e. gas-filled large aspect-ratio glass or plastic shells, driven by a strong laser-generated shock, are widely used as pulsed sources of neutrons and fast charged particles. Recent experiments on exploding pushers provided evidence for the transition from a purely fluid behavior to a kinetic one. Indeed, fluid models largely overpredict yield and temperature as the Knudsen number Kn (ratio of ion mean-free path to compressed gas radius) is comparable or larger than one. At Kn = 0.3 - 1, fluid codes reasonably estimate integral quantities as yield and neutron-averaged temperatures, but do not reproduce burn radii, burn profiles and DD/DHe3 yield ratio. This motivated a detailed simulation study of intermediate-Kn exploding pushers. We will show how simulation results depend on models for laser-interaction, electron conductivity (flux-limited local vs nonlocal), viscosity (physical vs artificial), and ion mixing. Work partially supported by Sapienza Project C26A15YTMA, Sapienza 2016 (n. 257584), and Eurofusion Project AWP17-ENR-IFE-CEA-01.

Magnetic shielding of large high-power-satellite solar arrays using internal currents

NASA Technical Reports Server (NTRS)

Parker, L. W.; Oran, W. A.

1979-01-01

Present concepts for solar power satellites involve dimensions up to tens of kilometers and operating internal currents up to hundreds of kiloamperes. A question addressed is whether the local magnetic fields generated by these strong currents during normal operation can shield the array against impacts by plasma ions and electrons (and from thruster plasmas) which can cause possible losses such as power leakage and surface erosion. One of several prototype concepts was modeled by a long narrow rectangular panel 2 km wide and 20 km long. The currents flow in a parallel across the narrow dimension (sheet current) and along the edge (wire currents). The wire currents accumulate from zero to 100 kiloamp and are the dominant sources. The magnetic field is approximated analytically. The equations of motion for charged particles in this magnetic field are analyzed. The ion and electron fluxes at points on the surface are represented analytically for monoenergetic distributions and are evaluated.

Inner-shell radiation from wire array implosions on the Zebra generator

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

Ouart, N. D.; Giuliani, J. L.; Dasgupta, A.

2014-03-15

Implosions of brass wire arrays on Zebra have produced L-shell radiation as well as inner-shell Kα and Kβ transitions. The L-shell radiation comes from ionization stages around the Ne-like charge state that is largely populated by a thermal electron energy distribution function, while the K-shell photons are a result of high-energy electrons ionizing or exciting an inner-shell (1s) electron from ionization stages around Ne-like. The K- and L-shell radiations were captured using two time-gated and two axially resolved time-integrated spectrometers. The electron beam was measured using a Faraday cup. A multi-zone non-local thermodynamic equilibrium pinch model with radiation transport ismore » used to model the x-ray emission from experiments for the purpose of obtaining plasma conditions. These plasma conditions are used to discuss some properties of the electron beam generated by runaway electrons. A simple model for runaway electrons is examined to produce the Kα radiation, but it is found to be insufficient.« less

SLAC All Access: Fermi Gamma-ray Space Telescope

ScienceCinema

Romani, Roger

2018-04-16

Three hundred and fifty miles overhead, the Fermi Gamma-ray Space Telescope silently glides through space. From this serene vantage point, the satellite's instruments watch the fiercest processes in the universe unfold. Pulsars spin up to 700 times a second, sweeping powerful beams of gamma-ray light through the cosmos. The hyperactive cores of distant galaxies spew bright jets of plasma. Far beyond, something mysterious explodes with unfathomable power, sending energy waves crashing through the universe. Stanford professor and KIPAC member Roger W. Romani talks about this orbiting telescope, the most advanced ever to view the sky in gamma rays, a form of light at the highest end of the energy spectrum that's created in the hottest regions of the universe.

Transverse Space-Charge Field-Induced Plasma Dynamics for Ultraintense Electron-Beam Characterization

NASA Astrophysics Data System (ADS)

Tarkeshian, R.; Vay, J. L.; Lehe, R.; Schroeder, C. B.; Esarey, E. H.; Feurer, T.; Leemans, W. P.

2018-04-01

Similarly to laser or x-ray beams, the interaction of sufficiently intense particle beams with neutral gases will result in the creation of plasma. In contrast to photon-based ionization, the strong unipolar field of a particle beam can generate a plasma where the electron population receives a large initial momentum kick and escapes, leaving behind unshielded ions. Measuring the properties of the ensuing Coulomb exploding ions—such as their kinetic energy distribution, yield, and spatial distribution—can provide information about the peak electric fields that are achieved in the electron beams. Particle-in-cell simulations and analytical models are presented for high-brightness electron beams of a few femtoseconds or even hundreds of attoseconds, and transverse beam sizes on the micron scale, as generated by today's free electron lasers. Different density regimes for the utilization as a potential diagnostics are explored, and the fundamental differences in plasma dynamical behavior for e-beam or photon-based ionization are highlighted. By measuring the dynamics of field-induced ions for different gas and beam densities, a lower bound on the beam charge density can be obtained in a single shot and in a noninvasive way. The exponential dependency of the ionization yield on the beam properties can provide unprecedented spatial and temporal resolution, at the submicrometer and subfemtosecond scales, respectively, offering a practical and powerful approach to characterizing beams from accelerators at the frontiers of performance.

Localized etching of an insulator film coated on a copper wire using an atmospheric-pressure microplasma jet.

PubMed

Yoshiki, Hiroyuki

2007-04-01

Atmospheric-pressure microplasma jets (APmicroPJs) of Ar and ArO(2) gases were generated from the tip of a stainless steel surgical needle having outer and inner diameters of 0.4 and 0.2 mm, respectively, with a rf excitation of 13.56 MHz. The steel needle functions both as a powered electrode and a gas nozzle. The operating power is 1.2-6 W and the corresponding peak-to-peak voltage Vp.p. is about 1.5 kV. The APmicroPJ was applied to the localized etching of a polyamide-imide insulator film (thickness of 10 microm) of a copper winding wire of 90 microm diameter. The insulator film around the copper wire was completely removed by the irradiated plasma from a certain direction without fusing the wire. The removal time under the Ar APmicroPJ irradiation was only 3 s at a rf power of 4 W. Fluorescence microscopy and scanning electron microscope images reveal that good selectivity of the insulator film to the copper wire was achieved. In the case of ArO(2) APmicroPJ irradiation with an O(2) concentration of 10% or more, the removed copper surface was converted to copper monoxide CuO.

Axial plasma jet characterization on a microsecond x-pinch

NASA Astrophysics Data System (ADS)

Jaar, G. S.; Appartaim, R. K.

2018-06-01

The jets produced on a microsecond x-pinch (quarter period T1/4 ˜ 1 μs, dI/dt ˜ 0.35 kA/ns) have been studied through light-field schlieren imaging and optical framing photographs across 4 different materials: Al, Ti, Mo, and W. The axial velocity of the jets was measured and exhibited no dependence on atomic number (Z) of the wire material. There may be a dependence on another factor(s), namely, the current rise rate. The average axial jet velocity across all four materials was measured to be 2.9 ± 0.5 × 106 cm/s. The average jet diameter and the average radial jet expansion rate displayed inverse relationships with Z, which may be attributed to radiative cooling and inertia. Asymmetry between the anode and cathode jet behavior was observed and is thought to be caused by electron beam activity. The mean divergence angle of the jet was found to vary with wire material and correlated inversely with the thermal conductivity of the cold wire. Optical images indicated a two-layer structure in Al jets which may be caused by standing shocks and resemble phenomena observed in astrophysical jet formation and collimation. Kinks in the jets have also been observed which may be caused by m = 1 MHD instability modes or by the interaction of the jet with the electrode plasma.

Growth of low temperature silicon nano-structures for electronic and electrical energy generation applications.

PubMed

Gabrielyan, Nare; Saranti, Konstantina; Manjunatha, Krishna Nama; Paul, Shashi

2013-02-15

This paper represents the lowest growth temperature for silicon nano-wires (SiNWs) via a vapour-liquid-solid method, which has ever been reported in the literature. The nano-wires were grown using plasma-enhanced chemical vapour deposition technique at temperatures as low as 150°C using gallium as the catalyst. This study investigates the structure and the size of the grown silicon nano-structure as functions of growth temperature and catalyst layer thickness. Moreover, the choice of the growth temperature determines the thickness of the catalyst layer to be used.The electrical and optical characteristics of the nano-wires were tested by incorporating them in photovoltaic solar cells, two terminal bistable memory devices and Schottky diode. With further optimisation of the growth parameters, SiNWs, grown by our method, have promising future for incorporation into high performance electronic and optical devices.

Growth of low temperature silicon nano-structures for electronic and electrical energy generation applications

PubMed Central

2013-01-01

This paper represents the lowest growth temperature for silicon nano-wires (SiNWs) via a vapour-liquid–solid method, which has ever been reported in the literature. The nano-wires were grown using plasma-enhanced chemical vapour deposition technique at temperatures as low as 150°C using gallium as the catalyst. This study investigates the structure and the size of the grown silicon nano-structure as functions of growth temperature and catalyst layer thickness. Moreover, the choice of the growth temperature determines the thickness of the catalyst layer to be used. The electrical and optical characteristics of the nano-wires were tested by incorporating them in photovoltaic solar cells, two terminal bistable memory devices and Schottky diode. With further optimisation of the growth parameters, SiNWs, grown by our method, have promising future for incorporation into high performance electronic and optical devices. PMID:23413969

Dynamic characteristics of azimuthally correlated structures of axial instability of wire-array Z pinches

NASA Astrophysics Data System (ADS)

Dan, Jia Kun; Huang, Xian Bin; Ren, Xiao Dong; Chen, Guang Hua; Xu, Qiang; Wang, Kun Lun; Ouyang, Kai; Wei, Bing

2017-04-01

Particular attention was placed on observations of dynamic properties of the azimuthally correlated structures of axial instability of wire-array Z pinches, which were conducted at 10-MA (for short circuit load) pulsed power generator-the Primary Test Stand facility. Not well fabricated loads, which were expected to preset bubble or spike in plasma, were used to degrade the implosion symmetry in order to magnify the phenomenon of instability. The side-view sequence of evolution of correlation given by laser shadowgraphy clearly demonstrates the dynamic processes of azimuthal correlation of the bubble and spike. A possible mechanism presented here suggests that it is the substantial current redistribution especially in regions surrounding the bubble/spike resulting from change of inductance due to the presence of the bubble/spike that plays an essential part in establishment of azimuthal correlation of wire array and liner Z pinches.

Observation of high-temperature bubbles in an ECR plasma

NASA Astrophysics Data System (ADS)

Terasaka, K.; Yoshimura, S.; Tanaka, M. Y.

2018-05-01

Creation and annihilation of high-temperature bubbles have been observed in an electron cyclotron resonance plasma. The electron temperature in the bubble core is three times higher than that in the ambient region, and the size perpendicular to the magnetic field is much smaller than the plasma diameter. Formation of a bubble accompanies large negative spikes in the floating potential of a Langmuir probe, and the spatiotemporal behavior of the bubble has been visualized with a high-impedance wire grid detector. It is found that the bubble is in a prolate spheroidal shape with the axis along the magnetic field and occurs randomly in time and independently in space.

Plasma microreactor in supercritical xenon and its application to diamondoid synthesis

NASA Astrophysics Data System (ADS)

Oshima, F.; Stauss, S.; Ishii, C.; Pai, D. Z.; Terashima, K.

2012-10-01

The generation of plasmas in a microreactor is demonstrated in xenon from atmospheric pressure up to supercritical conditions. Ac high voltage at a frequency of 15 kHz was applied across a 25-µm discharge gap between a tungsten wire and a fused silica micro-capillary tube in a coaxial configuration. Using this continuous flow supercritical fluid microreactor, it was possible to synthesize diamantane and other diamondoids up to nonamantane, using adamantane as a precursor and seed. It is anticipated that plasmas generated in supercritical fluid microreactors may not only allow faster fabrication of diamondoids, but also offer opportunities for the fabrication of other nanomaterials.

Development of high intensity X-ray sources at the National Ignition Facility

NASA Astrophysics Data System (ADS)

May, M. J.; Colvin, J. D.; Kemp, G. E.; Barrios, M. A.; Widmann, K.; Benjamin, R.; Thorn, D.; Poole, P.; Blue, B.

2018-05-01

Laser heated plasmas have provided recently some of the most powerful and energetic nanosecond length laboratory sources of x-ray photons (Ephoton = 1-30 keV). The highest x-ray to laser conversion is currently accessible by using underdense (ne ˜ 0.25 nc) plasmas since optimal laser coupling is obtained in millimeter scale targets. The targets can have conversion efficiencies of up to 10%. Several types of targets can be used to produce underdense plasmas: metal lined cylindrical cavities, gas pipes, and most recently nano-wire foams. Both the experimental and simulation details of these high intensity x-ray sources are discussed.

High-current electron gun with a planar magnetron integrated with an explosive-emission cathode

NASA Astrophysics Data System (ADS)

Kiziridi, P. P.; Ozur, G. E.

2017-05-01

A new high-current electron gun with plasma anode and explosive-emission cathode integrated with planar pulsed powered magnetron is described. Five hundred twelve copper wires 1 mm in diameter and 15 mm in height serve as emitters. These emitters are installed on stainless steel disc (substrate) with 3-mm distance between them. Magnetron discharge plasma provides increased ion density on the periphery of plasma anode formed by high-current Penning discharge ignited within several milliseconds after starting of the magnetron discharge. The increased on the periphery ion density improves the uniformity of high-current electron beam produced in such an electron gun.

Cavity temperature and flow characteristics in a gas-core test reactor

NASA Technical Reports Server (NTRS)

Putre, H. A.

1973-01-01

A test reactor concept for conducting basic studies on a fissioning uranium plasma and for testing various gas-core reactor concepts is analyzed. The test reactor consists of a conventional fuel-element region surrounding a 61-cm-(2-ft-) diameter cavity region which contains the plasma experiment. The fuel elements provide the neutron flux for the cavity region. The design operating conditions include 60-MW reactor power, 2.7-MW cavity power, 200-atm cavity pressure, and an average uranium plasma temperature of 15,000 K. The analytical results are given for cavity radiant heat transfer, hydrogen transpiration cooling, and uranium wire or powder injection.

Multilevel and Latent Variable Modeling with Composite Links and Exploded Likelihoods

ERIC Educational Resources Information Center

Rabe-Hesketh, Sophia; Skrondal, Anders

2007-01-01

Composite links and exploded likelihoods are powerful yet simple tools for specifying a wide range of latent variable models. Applications considered include survival or duration models, models for rankings, small area estimation with census information, models for ordinal responses, item response models with guessing, randomized response models,…

PHYSICAL AND OPTICAL PROPERTIES OF STEAM-EXPLODED LASER-PRINTED PAPER

EPA Science Inventory

Laser-printed paper was pulped by the steam-explosion process. A full-factorial experimental design was applied to determine the effects of key operating variables on the properties of steam-exploded pulp. The variables were addition level for pulping chemicals (NaOH and/or Na2SO...

Strategies to Reduce Tin and Other Metals in Electronic Cigarette Aerosol

PubMed Central

Williams, Monique; To, An; Bozhilov, Krassimir; Talbot, Prue

2015-01-01

Background Metals are present in electronic cigarette (EC) fluid and aerosol and may present health risks to users. Objective The objective of this study was to measure the amounts of tin, copper, zinc, silver, nickel and chromium in the aerosol from four brands of EC and to identify the sources of these metals by examining the elemental composition of the atomizer components. Methods Four brands of popular EC were dissected and the cartomizers were examined microscopically. Elemental composition of cartomizer components was determined using integrated energy dispersive X-ray microanalysis, and the concentrations of the tin, copper, zinc silver, nickel, and chromium in the aerosol were determined for each brand using inductively coupled plasma optical emission spectroscopy. Results All filaments were made of nickel and chromium. Thick wires were copper coated with either tin or silver. Wires were joined to each other by tin solder, brazing, or by brass clamps. High concentrations of tin were detected in the aerosol when tin solder joints were friable. Tin coating on copper wires also contributed to tin in the aerosol. Conclusions Tin concentrations in EC aerosols varied both within and between brands. Tin in aerosol was reduced by coating the thick wire with silver rather than tin, placing stable tin solder joints outside the atomizing chamber, joining wires with brass clamps or by brazing rather than soldering wires. These data demonstrate the feasibility of removing tin and other unwanted metals from EC aerosol by altering designs and using materials of suitable quality. PMID:26406602

Power consumption analysis DBD plasma ozone generator

NASA Astrophysics Data System (ADS)

Nur, M.; Restiwijaya, M.; Muchlisin, Z.; Susan, I. A.; Arianto, F.; Widyanto, S. A.

2016-11-01

Studies on the consumption of energy by an ozone generator with various constructions electrodes of dielectric barrier discharge plasma (DBDP) reactor has been carried out. This research was done to get the configuration of the reactor, that is capable to produce high ozone concentrations with low energy consumption. BDBP reactors were constructed by spiral- cylindrical configuration, plasma ozone was generated by high voltage AC voltage up to 25 kV and maximum frequency of 23 kHz. The reactor consists of an active electrode in the form of a spiral-shaped with variation diameter Dc, and it was made by using copper wire with diameter Dw. In this research, we variated number of loops coil windings N as well as Dc and Dw. Ozone concentrations greater when the wire's diameter Dw and the diameter of the coil windings applied was greater. We found that impedance greater will minimize the concentration of ozone, in contrary to the greater capacitance will increase the concentration of ozone. The ozone concentrations increase with augmenting of power. Maximum power is effective at DBD reactor spiral-cylinder is on the Dc = 20 mm, Dw = 1.2 mm, and the number of coil windings N = 10 loops with the resulting concentration is greater than 20 ppm and it consumes energy of 177.60 watts

X-ray imaging and 3D reconstruction of in-flight exploding foil initiator flyers

DOE PAGES

Willey, T. M.; Champley, K.; Hodgin, R.; ...

2016-06-17

Exploding foil initiators (EFIs), also known as slapper initiators or detonators, offer clear safety and timing advantages over other means of initiating detonation in high explosives. The work described here outlines a new capability for imaging and reconstructing three-dimensional images of operating EFIs. Flyer size and intended velocity were chosen based on parameters of the imaging system. The EFI metal plasma and plastic flyer traveling at 2.5 km/s were imaged with short ~80 ps pulses spaced 153.4 ns apart. A four-camera system acquired 4 images from successive x-ray pulses from each shot. The first frame was prior to bridge burst,more » the 2 nd images the flyer about 0.16 mm above the surface but edges of the foil and/or flyer are still attached to the substrate. The 3 rd frame captures the flyer in flight, while the 4 th shows a completely detached flyer in a position that is typically beyond where slappers strike initiating explosives. Multiple acquisitions at different incident angles and advanced computed tomography reconstruction algorithms were used to produce a 3-dimensional image of the flyer at 0.16 and 0.53 mm above the surface. Both the x-ray images and the 3D reconstruction show a strong anisotropy in the shape of the flyer and underlying foil parallel vs. perpendicular to the initiating current and electrical contacts. These results provide detailed flyer morphology during the operation of the EFI.« less

X-ray imaging and 3D reconstruction of in-flight exploding foil initiator flyers

NASA Astrophysics Data System (ADS)

Willey, T. M.; Champley, K.; Hodgin, R.; Lauderbach, L.; Bagge-Hansen, M.; May, C.; Sanchez, N.; Jensen, B. J.; Iverson, A.; van Buuren, T.

2016-06-01

Exploding foil initiators (EFIs), also known as slapper initiators or detonators, offer clear safety and timing advantages over other means of initiating detonation in high explosives. This work outlines a new capability for imaging and reconstructing three-dimensional images of operating EFIs. Flyer size and intended velocity were chosen based on parameters of the imaging system. The EFI metal plasma and plastic flyer traveling at 2.5 km/s were imaged with short ˜80 ps pulses spaced 153.4 ns apart. A four-camera system acquired 4 images from successive x-ray pulses from each shot. The first frame was prior to bridge burst, the 2nd images the flyer about 0.16 mm above the surface but edges of the foil and/or flyer are still attached to the substrate. The 3rd frame captures the flyer in flight, while the 4th shows a completely detached flyer in a position that is typically beyond where slappers strike initiating explosives. Multiple acquisitions at different incident angles and advanced computed tomography reconstruction algorithms were used to produce a 3-dimensional image of the flyer at 0.16 and 0.53 mm above the surface. Both the x-ray images and the 3D reconstruction show a strong anisotropy in the shape of the flyer and underlying foil parallel vs. perpendicular to the initiating current and electrical contacts. These results provide detailed flyer morphology during the operation of the EFI.

X-ray imaging and 3D reconstruction of in-flight exploding foil initiator flyers

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

Willey, T. M., E-mail: willey1@llnl.gov; Champley, K., E-mail: champley1@llnl.gov; Hodgin, R.

Exploding foil initiators (EFIs), also known as slapper initiators or detonators, offer clear safety and timing advantages over other means of initiating detonation in high explosives. This work outlines a new capability for imaging and reconstructing three-dimensional images of operating EFIs. Flyer size and intended velocity were chosen based on parameters of the imaging system. The EFI metal plasma and plastic flyer traveling at 2.5 km/s were imaged with short ∼80 ps pulses spaced 153.4 ns apart. A four-camera system acquired 4 images from successive x-ray pulses from each shot. The first frame was prior to bridge burst, the 2nd images themore » flyer about 0.16 mm above the surface but edges of the foil and/or flyer are still attached to the substrate. The 3rd frame captures the flyer in flight, while the 4th shows a completely detached flyer in a position that is typically beyond where slappers strike initiating explosives. Multiple acquisitions at different incident angles and advanced computed tomography reconstruction algorithms were used to produce a 3-dimensional image of the flyer at 0.16 and 0.53 mm above the surface. Both the x-ray images and the 3D reconstruction show a strong anisotropy in the shape of the flyer and underlying foil parallel vs. perpendicular to the initiating current and electrical contacts. These results provide detailed flyer morphology during the operation of the EFI.« less

X-ray imaging and 3D reconstruction of in-flight exploding foil initiator flyers

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

Willey, T. M.; Champley, K.; Hodgin, R.

Exploding foil initiators (EFIs), also known as slapper initiators or detonators, offer clear safety and timing advantages over other means of initiating detonation in high explosives. The work described here outlines a new capability for imaging and reconstructing three-dimensional images of operating EFIs. Flyer size and intended velocity were chosen based on parameters of the imaging system. The EFI metal plasma and plastic flyer traveling at 2.5 km/s were imaged with short ~80 ps pulses spaced 153.4 ns apart. A four-camera system acquired 4 images from successive x-ray pulses from each shot. The first frame was prior to bridge burst,more » the 2 nd images the flyer about 0.16 mm above the surface but edges of the foil and/or flyer are still attached to the substrate. The 3 rd frame captures the flyer in flight, while the 4 th shows a completely detached flyer in a position that is typically beyond where slappers strike initiating explosives. Multiple acquisitions at different incident angles and advanced computed tomography reconstruction algorithms were used to produce a 3-dimensional image of the flyer at 0.16 and 0.53 mm above the surface. Both the x-ray images and the 3D reconstruction show a strong anisotropy in the shape of the flyer and underlying foil parallel vs. perpendicular to the initiating current and electrical contacts. These results provide detailed flyer morphology during the operation of the EFI.« less

Method for defect free keyhole plasma arc welding

NASA Technical Reports Server (NTRS)

Harwig, Dennis D. (Inventor); Hunt, James F. (Inventor); Ryan, Patrick M. (Inventor); Fisher, Walter J. (Inventor)

1993-01-01

A plasma arc welding process for welding metal of increased thickness with one pass includes operating the plasma arc welding apparatus at a selected plasma gas flow rate, travel speed and arc current, to form a weld having a penetration ratio to weld height to weld width, and maintaining the penetration ratio at less than 0.74. Parameters for the plasma gas flow rate, travel speed and arc current are adjusted to a steady state condition during a start up period and maintained during the steady state condition to complete a weld. During a terminal stopping period, the travel speed is stopped and instantaneously replaced by filler wire which adds material to fill the keyhole that had been formed by the welding process. Parameters are subsequently adjusted during the stopping period to terminate the weld in a sound manner.

Wheelbarrow tire explosion causing trauma to the forearm and hand: a case report

PubMed Central

2009-01-01

Introduction Tire explosion injuries are rare, but they may result in a severe injury pattern. Case reports and statistics from injuries caused by exploded truck tires during servicing are established, but trauma from exploded small tires seems to be unknown. Case presentation A 47-year-old german man inflated a wheelbarrow tire. The tire exploded during inflation and caused an open, multiple forearm and hand injury. Conclusion Even small tires can cause severe injury patterns in the case of an explosion. High inflating pressures and low safety distances are the main factors responsible for this occurrence. Broad safety information and suitable filling devices are indispensable for preventing these occurrences. PMID:19946543

Modeling Initiation in Exploding Bridgewire Detonators

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

Hrousis, C A

2005-05-18

One- and two-dimensional models of initiation in detonators are being developed for the purpose of evaluating the performance of aged and modified detonator designs. The models focus on accurate description of the initiator, whether it be an EBW (exploding bridgewire) that directly initiates a high explosive powder or an EBF (exploding bridgefoil) that sends an inert flyer into a dense HE pellet. The explosion of the initiator is simulated using detailed MHD equations of state as opposed to specific action-based phenomenological descriptions. The HE is modeled using the best available JWL equations of state. Results to date have been promising,more » however, work is still in progress.« less

Clinical features of the exploding head syndrome.

PubMed

Pearce, J M

1989-07-01

Fifty patients suffering from the "exploding head syndrome" are described. This hitherto unreported syndrome is characterised by a sense of an explosive noise in the head usually in the twilight stage of sleep. The associated symptoms are varied, but the benign nature of the condition is emphasised and neither extensive investigation nor treatment are indicated.

Exploding Boxes

ERIC Educational Resources Information Center

Kinney; Jan

2011-01-01

How do you teach the "same old, same old" in an interesting and inexpensive way? Art teachers are forever looking for new angles on the good-old elements and principles. And, as budgets tighten, they are trying to be as frugal as possible while still holding their students' attention. Enter exploding boxes! In conceptualizing the three types of…

The Exploding and Explosive Two-Year College.

ERIC Educational Resources Information Center

McPherson, Elisabeth

Junior and community colleges must explode many traditional notions about education in order to fulfill their promises to poor and disadvantaged students. The number of junior and community colleges and the number of students attending them have increased rapidly in the past few years. But many communities think that community colleges didn't keep…

Asteroids and Comets Outreach Compilation

NASA Technical Reports Server (NTRS)

1999-01-01

Contents include various different animations in the area of Asteroids and Comets. Titles of the short animated clips are: STARDUST Mission; Asteroid Castallia Impact Simulation; Castallia, Toutatis and the Earth; Simulation Asteroid Encounter with Earth; Nanorover Technology Task; Near Earth Asteroid Tracking; Champollian Anchor Tests; Early Views of Comets; Exploration of Small Bodies; Ulysses Resource Material from ESA; Ulysses Cometary Plasma Tail Animation; and various discussions on the Hale-Bopp Comet. Animation of the following are seen: the Stardust aerogel collector grid collecting cometary dust particles, comet and interstellar dust analyzer, Wiper-shield and dust flux monitor, a navigation camera, and the return of the sample to Earth; a comparison of the rotation of the Earth to the Castallia and Tautatis Asteroids; an animated land on Tautatis and the view of the motion of the sky from its surface; an Asteroid collision with the Earth; the USAF Station in Hawaii; close-up views of asteroids; automatic drilling of the Moon; exploding Cosmic Particles; and the dropping off of the plasma tail of a comet as it travels near the sun.

Searches for comet-induced solar flares

NASA Astrophysics Data System (ADS)

Ibadov, Subhon; Ibodov, Firuz

During the last decade we have carried out analytical consideration of the impacts of comets with the Sun: the study of passage of cometary nuclei through the solar chromosphere and photosphere was carried out taking into account aerodynamic crushing of the nucleus, transversal expansion of the crushed mass and aerodynamic deceleration of the flattening structure. The results indicate that the stopping of the hypervelocity, more than 600 km/s, comet matter near the photosphere has essentially "explosive" character and will be accompanied by generation of a strong "blast" shock wave as well as ejection of a hot plasma from a relatively very thin,"exploding", near-photosphere layer. Observational manifestations of these processes, comet-induced solar flares, CISF, will be anomalous line emission of metal atoms/ions like Fe, Si, etc. from chromosphere/corona regions and continuum emission of a high-temperature, around 10^6-10^7 K, plasma cloud near the solar surface. Space observations of the phenomena by solar telescopes, including future out-of-ecliptic ones, are of interest for the physics/prognosis of solar flares as well as physics of comets.

Astrophysically relevant radiatively cooled hypersonic bow shocks in nested wire arrays

NASA Astrophysics Data System (ADS)

Ampleford, David

2009-11-01

We have performed laboratory experiments which introduce obstructions into hypersonic plasma flows to study the formation of shocks. Astrophysical observations have demonstrated many examples of equivalent radiatively cooled bow shocks, for example the head of protostellar jets or supernova remnants passing through the interstellar medium or between discrete clumps in jets. Wire array z-pinches allow us to study quasi-planar radiatively cooled flows in the laboratory. The early stage of a wire array z-pinch implosion consists of a steady flow of the wire material towards the axis. Given a high rate of radiative cooling, these flows reach high sonic- Mach numbers, typically up to 5. The 2D nature of this configuration allows the insertion of obstacles into the flow, such as a concentric ``inner'' wire array, as has previously been studied for ICF research. Here we study the application of such a nested array to laboratory astrophysics where the inner wires act as obstructions perpendicular to the flow, and induce bow shocks. By varying the wire array material (W/Al), the significance of radiative cooling on these shocks can be controlled, and is shown to change the shock opening angle. As multiple obstructions are present, the experiments show the interaction of multiple bow shocks. It is also possible to introduce a magnetic field around the static object, increasing the opening angle of the shocks. Further experiments can be designed to control the flow density, magnetic field structure and obstruction locations. In collaboration with: S.V. Lebedev, M.E. Cuneo, C.A. Jennings, S.N. Bland, J.P. Chittenden, A. Ciardi, G.N. Hall, S.C. Bott, M. Sherlock, A. Frank, E. Blackman

Wire Probe Antenna (WPT) and Electric Field Detector (EFD0 of Plasma Wave Experiment (PWE) aboard ARASE: Specifications and Evaluation results

NASA Astrophysics Data System (ADS)

Matsuda, S.; Kasaba, Y.; Ishisaka, K.; Kasahara, Y.; Imachi, T.; Yagitani, S.; Kojima, H.; Kurita, S.; Shoji, M.; Hori, T.; Shinbori, A.; Teramoto, M.; Miyoshi, Y.; Nakagawa, T.; Takahashi, N.; Nishimura, Y.; Matsuoka, A.; Tsuchiya, F.; Kumamoto, A.; Nomura, R.

2017-12-01

This paper summarizes the specifications and the evaluation results of Wire Probe Antenna (WPT) and Electric Field Detector (EFD), which are the key parts of Plasma Wave Experiment (PWE) aboard the Arase satellite, in their initial operations and the beginning phase of the full observations. WPT consists of the two dipole antennas as electric field sensors with 32m tip-to-tip length, with a sphere probe (6 cm diameter) attached at each end of wires (length: 15-m). They are extended orthogonally in the spin plane which is roughly perpendicular to the Sun. It enables the PWE to measure the E-field from DC to 10 MHz. This system is almost compatible to the WPT of the Plasma Wave Investigation (PWI) aboard BepiColombo Mercury Magnetospheric Orbiter, except the material of the spherical probe (ERG: Aluminium alloy, MMO: Titanium-alloy). This paper shows the extended length evaluated by the Lorentz force (spacecraft velocity x B-field) and the antenna impedance as the basic information of the E-field measurement capability of the PWE E-field receivers, with the evaluation for the possible degradation of the probe surface coated by TiAlN as BepiColombo. EFD is the 2-channel low frequency electric receiver as a part of EWO (EFD/WFC/OFA), for the measurement of 2ch electric field in the spin-plane with the sampling rate of 512 Hz (dynamic range: +-200 mV/m, +-3 V/m) and the 4ch spacecraft potential with the sampling rate of 128 Hz (dynamic range: +-100 V), respectively, with the bias control capability fed to the WPT probes. The electric field in DC - 232Hz provides the capability to detect (1) the fundamental information of the plasma dynamics and accelerations and (2) the characteristics of MHD and ion waves with their Poynting vectors with the data measured by MGF and PWE/WFC-B connected to PWE/SCM. The spacecraft potential provides the electron density information with UHR frequency. This paper also introduces the data sets and their calibration status.

Time-resolved spectra of dense plasma focus using spectrometer, streak camera, and CCD combination.

PubMed

Goldin, F J; Meehan, B T; Hagen, E C; Wilkins, P R

2010-10-01

A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny-Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments.

Characterization of laser-cut copper foil X-pinches

NASA Astrophysics Data System (ADS)

Collins, G. W.; Valenzuela, J. C.; Hansen, S. B.; Wei, M. S.; Reed, C. T.; Forsman, A. C.; Beg, F. N.

2016-10-01

Quantitative data analyses of laser-cut Cu foil X-pinch experiments on the 150 ns quarter-period, ˜250 kA GenASIS driver are presented. Three different foil designs are tested to determine the effects of initial structure on pinch outcome. Foil X-pinch data are also presented alongside the results from wire X-pinches with comparable mass. The X-ray flux and temporal profile of the emission from foil X-pinches differed significantly from that of wire X-pinches, with all emission from the foil X-pinches confined to a ˜3 ns period as opposed to the delayed, long-lasting electron beam emission common in wire X-pinches. Spectroscopic data show K-shell as well as significant L-shell emission from both foil and wire X-pinches. Fits to synthetic spectra using the SCRAM code suggest that pinching foil X's produced a ˜1 keV, ne ≥ 1023 cm-3 plasma. The spectral data combined with the improved reliability of the source timing, flux, and location indicate that foil X-pinches generate a reproducible, K-shell point-projection radiography source that can be easily modified and tailored to suit backlighting needs across a variety of applications.

Carbon Nanospikes Grown on Metal Wires as Microelectrode Sensors for Dopamine

PubMed Central

Zestos, Alexander G.; Yang, Cheng; Jacobs, Christopher B.; Hensley, Dale; Venton, B. Jill

2015-01-01

Carbon nanomaterials are advantageous as electrodes for neurotransmitter detection, but the difficulty of nanomaterials deposition on electrode substrates limits the reproducibility and future applications. In this study, we used plasma enhanced chemical vapor deposition (PECVD) to directly grow a thin layer of carbon nanospikes (CNS) on cylindrical metal substrates. No catalyst is required and the CNS surface coverage is uniform over the cylindrical metal substrate. The CNS growth was characterized on several metallic substrates including tantalum, niobium, palladium, and nickel wires. Using fast-scan cyclic voltammetry (FSCV), bare metal wires could not detect 1 μM dopamine while carbon nanospike coated wires could. The highest sensitivity and optimized S/N ratio was recorded from carbon nanospike-tantalum (CNS-Ta) microwires grown for 7.5 minutes, which had a LOD of 8 ± 2 nM for dopamine with FSCV. CNS-Ta microelectrodes were more reversible and had a smaller ΔEp for dopamine than carbon-fiber microelectrodes, suggesting faster electron transfer kinetics. The kinetics of dopamine redox were adsorption controlled at CNS-Ta microelectrodes and repeated electrochemical measurements displayed stability for up to ten hours in vitro and over a ten day period as well. The oxidation potential was significantly different for ascorbic acid and uric acid compared to dopamine. Growing carbon nanospikes on metal wires is a promising method to produce uniformly-coated, carbon nanostructured cylindrical microelectrodes for sensitive dopamine detection. PMID:26389138

Analysis of plasma characteristics and conductive mechanism of laser assisted pulsed arc welding

NASA Astrophysics Data System (ADS)

Liu, Shuangyu; Chen, Shixian; Wang, Qinghua; Li, Yanqing; Zhang, Hong; Ding, Hongtao

2017-05-01

This study aims to investigate the arc plasma shape and the spectral characteristics during the laser assisted pulsed arc welding process. The arc plasma shape was synchronously observed using a high speed camera, and the emission spectrum of plasma was obtained by spectrometer. The well-known Boltzmann plot method and Stark broadening were used to calculate the electron temperature and density respectively. The conductive mechanism of arc ignition in laser assisted arc hybrid welding was investigated, and it was found that the plasma current moved to the arc anode under the action of electric field. Thus, a significant parabolic channel was formed between the keyhole and the wire tip. This channel became the main method of energy transformation between the arc and the molten pool. The calculation results of plasma resistivity show that the laser plasma has low resistivity as the starting point of conductive channel formation. When the laser pulse duration increases, the intensity of the plasma radiation spectrum and the plasma electron density will increase, and the electron temperature will decrease.

Clinical features of the exploding head syndrome.

PubMed Central

Pearce, J M

1989-01-01

Fifty patients suffering from the "exploding head syndrome" are described. This hitherto unreported syndrome is characterised by a sense of an explosive noise in the head usually in the twilight stage of sleep. The associated symptoms are varied, but the benign nature of the condition is emphasised and neither extensive investigation nor treatment are indicated. PMID:2769286

Deflagration-to-detonation characteristics of a laser exploding bridge detonator

NASA Astrophysics Data System (ADS)

Welle, E. J.; Fleming, K. J.; Marley, S. K.

2006-08-01

Evaluation of laser initiated explosive trains has been an area of extreme interest due to the safety benefits of these systems relative to traditional electro-explosive devices. A particularly important difference is these devices are inherently less electro-static discharge (ESD) sensitive relative to traditional explosive devices due to the isolation of electrical power and associated materials from the explosive interface. This paper will report work conducted at Sandia National Laboratories' Explosive Components Facility, which evaluated the initiation and deflagration-to-detonation characteristics of a Laser Driven Exploding Bridgewire detonator. This paper will report and discuss characteristics of Laser Exploding Bridgewire devices loaded with hexanitrohexaazaisowurtzitane (CL-20) and tetraammine-cis-bis-(5-nitro-2H-tetrazolato-N2) cobalt (III) perchlorate (BNCP).

On Heating the Sun's Corona by Magnetic Explosions: Feasibility in Active Regions and prospects for Quiet Regions and Coronal Holes

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, D. A.; Porter, Jason G.; Suess, Steven T.

1999-01-01

We build a case for the persistent strong coronal heating in active regions and the pervasive quasi-steady heating of the corona in quiet regions and coronal holes being driven in basically the same way as the intense transient heating in solar flares: by explosions of sheared magnetic fields in the cores of initially closed bipoles. We begin by summarizing the observational case for exploding sheared core fields being the drivers of a wide variety of flare events, with and without coronal mass ejections. We conclude that the arrangement of an event's flare heating, whether there is a coronal mass ejection, and the time and place of the ejection relative to the flare heating are all largely determined by four elements of the form and action of the magnetic field: (1) the arrangement of the impacted, interacting bipoles participating in the event, (2) which of these bipoles are active (have sheared core fields that explode) and which are passive (are heated by injection from impacted active bipoles), (3) which core field explodes first, and (4) which core-field explosions are confined within the closed field of their bipoles and which ejectively open their bipoles. We then apply this magnetic-configuration framework for flare heating to the strong coronal heating observed by the Yohkoh Soft X-ray Telescope in an active region with strongly sheared core fields observed by the MSFC vector magnetograph. All of the strong coronal heating is in continually microflaring sheared core fields or in extended loops rooted against the active core fields. Thus, the strong heating occurs in field configurations consistent with the heating being driven by frequent core-field explosions that are smaller but similar to those in confined flares and flaring arches. From analysis of the thermal and magnetic energetics of two selected core-field microflares and a bright extended loop, we find that (1) it is energetically feasible for the sheared core fields to drive all of the coronal heating in the active region via a staccato of magnetic microexplosions, (2) the microflares at the feet of the extended loop behave as the flares at the feet of flaring arches in that more coronal heating is driven within the active bipole than in the extended loop, (3) the filling factor of the X-ray plasma in the core field microflares and in the extended loop is approximately 0.1, and (4) to release enough magnetic energy for a typical microflare (10^27 - 10^28 erg), a microflaring strand of sheared core field need expand and/or untwist by only a few percent at most. Finally, we point out that (1) the field configurations for strong coronal heating in our example active region (i.e., neutral-line core fields, many embedded in the feet of extended loops) are present in abundance in the magnetic network in quiet regions and coronal holes, and (2) it is known that many network bipoles do microflare and that many produce detectable coronal heating. We therefore propose that exploding sheared core fields are the drivers of most of the heating and dynamics of the solar atmosphere, ranging from the largest and most powerful coronal mass ejections and flares, to the vigorous microflaring and coronal heating in active regions, to the multitude of fine-scale explosive events in the magnetic network. The low-lysing exploding core fields in the network drive microflares, spicules, global coronal heating, and ,consequently, the solar wind.

Automotive Airbag Safety Enhancement Final Report CRADA No. TSB-1165-95

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

Cutting, Jack; Durrell, Robert

The Vehicle Safety systems (VSS) Division of Quantic Industries, Inc. (QII) manufactured automotive airbag components. When both the driver and the passenger side airbags inflated in a tightly sealed passenger compartment, the compression of the surrounding air could and, in some instances, would cause damage to the eardrums of the occupants. The Aerospace and Division (ADD) of QII had partially developed the technology to fracture the canopy of a jet aircraft at the time of pilot ejection. The technical problem was how to adapt the canopy fracturing technology to the rear window of a motor vehicle in a safe andmore » cost effective manner. The existing approach was to replace the embedded rear window defroster with a series-parallel network of exploding bridge wires (EBWs). This would still provide the defrost function at low voltage/ current, but would cause fracturing of the window when a high current/voltage pulse was applied without pyrotechnics or explosives. The elements of this system were the embedded EBW network and a trunk-mounted fireset. The fireset would store the required energy to fire the network upon the receipt of a trigger signal from the existing air bag crash sensor.« less

Spark gap device for precise switching

DOEpatents

Boettcher, Gordon E.

1984-01-01

A spark gap device for precise switching of an energy storage capacitor into an exploding bridge wire load is disclosed. Niobium electrodes having a melting point of 2,415 degrees centrigrade are spaced apart by an insulating cylinder to define a spark gap. The electrodes are supported by conductive end caps which, together with the insulating cylinder, form a hermetically sealed chamber filled with an inert, ionizable gas, such as pure xenon. A quantity of solid radioactive carbon-14 within the chamber adjacent the spark gap serves as a radiation stabilizer. The sides of the electrodes and the inner wall of the insulating cylinder are spaced apart a sufficient distance to prevent unwanted breakdown initiation. A conductive sleeve may envelop the outside of the insulating member from the midpoint of the spark gap to the cap adjacent the cathode. The outer metallic surfaces of the device may be coated with a hydrogen-impermeable coating to lengthen the shelf life and operating life of the device. The device breaks down at about 1,700 volts for input voltage rates up to 570 volts/millisecond and allows peak discharge currents of up to 3,000 amperes from a 0.3 microfarad energy storage capacitor for more than 1,000 operations.

Electron temperature diagnostics of aluminium plasma in a z-pinch experiment at the “QiangGuang-1" facility

NASA Astrophysics Data System (ADS)

Li, Mo; Wu, Jian; Wang, Liang-Ping; Wu, Gang; Han, Juan-Juan; Guo, Ning; Qiu, Meng-Tong

2012-12-01

Two curved crystal spectrometers are set up on the “QiangGuang-1" generator to measure the z-pinch plasma spectra emitted from planar aluminum wire array loads. Kodak Biomax-MS film and an IRD AXUVHS5# array are employed to record time-integrated and time-resolved free-bound radiation, respectively. The photon energy recorded by each detector is ascertained by using the L-shell lines of molybdenum plasma. Based on the exponential relation between the continuum power and photon energies, the aluminum plasma electron temperatures are measured. For the time-integrated diagnosis, several “bright spots" indicate electron temperatures between (450 eV ~ 520 eV) ± 35%. And for the time-resolved ones, the result shows that the electron temperature reaches about 800 eV ± 30% at peak power. The system satisfies the demand of z-pinch plasma electron temperature diagnosis on a ~ 1 MA facility.

Investigation of an Oscillating Surface Plasma for Turbulent Drag Reduction

NASA Technical Reports Server (NTRS)

Wilkinson, Stephen P.

2003-01-01

An oscillating, weakly ionized surface plasma has been investigated for use in turbulent boundary layer viscous drag reduction. The study was based on reports showing that mechanical spanwise oscillations of a wall can reduce viscous drag due to a turbulent boundary layer by up to 40%. It was hypothesized that the plasma induced body force in high electric field gradients of a surface plasma along strip electrodes could also be configured to oscillate the flow. Thin dielectric panels with millimeter-scale, flush- mounted, triad electrode arrays with one and two-phase high voltage excitation were tested. Results showed that while a small oscillation could be obtained, the effect was lost at a low frequency (less than 100Hz). Furthermore, a mean flow was generated during the oscillation that complicates the effect. Hot-wire and pitot probe diagnostics are presented along with phase-averaged images revealing plasma structure.

New tools for “hot-wiring” clathrin-mediated endocytosis with temporal and spatial precision

PubMed Central

2017-01-01

Clathrin-mediated endocytosis (CME) is the major route of receptor internalization at the plasma membrane. Analysis of constitutive CME is difficult because the initiation of endocytic events is unpredictable. When and where a clathrin-coated pit will form and what cargo it will contain are difficult to foresee. Here we describe a series of genetically encoded reporters that allow the initiation of CME on demand. A clathrin-binding protein fragment (“hook”) is inducibly attached to an “anchor” protein at the plasma membrane, which triggers the formation of new clathrin-coated vesicles. Our design incorporates temporal and spatial control by the use of chemical and optogenetic methods for inducing hook–anchor attachment. Moreover, the cargo is defined. Because several steps in vesicle creation are bypassed, we term it “hot-wiring.” We use hot-wired endocytosis to describe the functional interactions between clathrin and AP2. Two distinct sites on the β2 subunit, one on the hinge and the other on the appendage, are necessary and sufficient for functional clathrin engagement. PMID:28954824

Properties of thermal air plasma with admixing of copper and carbon

NASA Astrophysics Data System (ADS)

Fesenko, S.; Veklich, A.; Boretskij, V.; Cressault, Y.; Gleizes, A.; Teulet, Ph

2014-11-01

This paper deals with investigations of air plasma with admixing of copper and carbon. Model plasma source unit with real breaking arc was used for the simulation of real discharges, which can be occurred during sliding of Cu-C composite electrodes on copper wire at electromotive vehicles. The complex technique of plasma property studies is developed. From one hand, the radial profiles of temperature and electron density in plasma of electric arc discharge in air between Cu-C composite and copper electrodes in air flow were measured by optical spectroscopy techniques. From another hand, the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. It was assumed that the thermal conductivity of air plasma is not depending on copper or carbon vapor admixtures. The electron density is obtained from electric conductivity profiles by calculation in assumption of local thermodynamic equilibrium in plasma. Computed in such way radial profiles of electron density in plasma of electric arc discharge in air between copper electrodes were compared with experimentally measured profiles. It is concluded that developed techniques of plasma diagnostics can be reasonably used in investigations of thermal plasma with copper and carbon vapors.

Revival of the fittest: exploding core-collapse supernovae from 12 to 25 M⊙

NASA Astrophysics Data System (ADS)

Vartanyan, David; Burrows, Adam; Radice, David; Skinner, M. Aaron; Dolence, Joshua

2018-07-01

We present results of 2D axisymmetric core-collapse supernova simulations, employing the FORNAX code, of nine progenitor models spanning 12 to 25 M⊙. Four of the models explode with inelastic scattering off electrons and neutrons as well as the many-body correction to neutrino-nucleon scattering opacities. We show that these four models feature sharp Si-O interfaces in their density profiles, and that the corresponding dip in density reduces the accretion rate around the stalled shock and prompts explosion. The non-exploding models lack such a steep feature, highlighting the Si-O interface as one key to explosion. Furthermore, we show that all of the non-exploding models can be nudged to explosion with modest changes to macrophysical inputs, including moderate rotation and perturbations to infall velocities, as well as to microphysical inputs, including reasonable changes to neutrino-nucleon interaction rates, suggesting that all the models are perhaps close to criticality. Exploding models have energies of a few × 1050 erg at the end of our simulation, and are rising, emphasizing the need to continue these simulations over larger grids and for longer times to reproduce the energies seen in nature. Morphology of the explosion contributes to the explosion energy, with more isotropic ejecta producing larger explosion energies. We do not find evidence for the Lepton-number Emission Self-sustained Asymmetry. Finally, we look at proto-neutron star (PNS) properties and explore the role of dimension in our simulations. We find that convection in the PNS produces larger PNS radii as well as greater `νμ' luminosities in 2D compared to 1D.

Revival of the Fittest: Exploding Core-Collapse Supernovae from 12 to 25 M⊙

NASA Astrophysics Data System (ADS)

Vartanyan, David; Burrows, Adam; Radice, David; Skinner, M. Aaron; Dolence, Joshua

2018-03-01

We present results of 2D axisymmetric core-collapse supernova simulations, employing the FORNAX code, of nine progenitor models spanning 12 to 25 M⊙. Four of the models explode with inelastic scattering off electrons and neutrons as well as the many-body correction to neutrino-nucleon scattering opacities. We show that these four models feature sharp Si-O interfaces in their density profiles, and that the corresponding dip in density reduces the accretion rate around the stalled shock and prompts explosion. The non-exploding models lack such a steep feature, highlighting the Si-O interface as one key to explosion. Furthermore, we show that all of the non-exploding models can be nudged to explosion with modest changes to macrophysical inputs, including moderate rotation and perturbations to infall velocities, as well as to microphysical inputs, including reasonable changes to neutrino-nucleon interaction rates, suggesting that all the models are perhaps close to criticality. Exploding models have energies of few × 1050 ergs at the end of our simulation, and are rising, emphasizing the need to continue these simulations over larger grids and for longer times to reproduce the energies seen in Nature. Morphology of the explosion contributes to the explosion energy, with more isotropic ejecta producing larger explosion energies. We do not find evidence for the Lepton-number Emission Self-Sustained Asymmetry. Finally, we look at PNS properties and explore the role of dimension in our simulations. We find that convection in the proto-neutron star (PNS) produces larger PNS radii as well as greater "νμ" luminosities in 2D compared to 1D.

Spatially resolved single crystal x-ray spectropolarimetry of wire array z-pinch plasmas

NASA Astrophysics Data System (ADS)

Wallace, M. S.; Haque, S.; Neill, P.; Pereira, N. R.; Presura, R.

2018-01-01

A recently developed single-crystal x-ray spectropolarimeter has been used to record paired sets of polarization-dependent and axially resolved x-ray spectra emitted by wire array z-pinches. In this measurement, two internal planes inside a suitable crystal diffract the x-rays into two perpendicular directions that are normal to each other, thereby separating incident x-rays into their linearly polarized components. This paper gives considerations for fielding the instrument on extended sources. Results from extended sources are difficult to interpret because generally the incident x-rays are not separated properly by the crystal. This difficulty is mitigated by using a series of collimating slits to select incident x-rays that propagate in a plane of symmetry between the polarization-splitting planes. The resulting instrument and some of the spatially resolved polarized x-ray spectra recorded for a 1-MA aluminum wire array z-pinch at the Nevada Terawatt Facility at the University of Nevada, Reno will be presented.

Investigations of ultrafast charge dynamics in laser-irradiated targets by a self probing technique employing laser driven protons

NASA Astrophysics Data System (ADS)

Ahmed, H.; Kar, S.; Cantono, G.; Nersisyan, G.; Brauckmann, S.; Doria, D.; Gwynne, D.; Macchi, A.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

2016-09-01

The divergent and broadband proton beams produced by the target normal sheath acceleration mechanism provide the unique opportunity to probe, in a point-projection imaging scheme, the dynamics of the transient electric and magnetic fields produced during laser-plasma interactions. Commonly such experimental setup entails two intense laser beams, where the interaction produced by one beam is probed with the protons produced by the second. We present here experimental studies of the ultra-fast charge dynamics along a wire connected to laser irradiated target carried out by employing a 'self' proton probing arrangement - i.e. by connecting the wire to the target generating the probe protons. The experimental data shows that an electromagnetic pulse carrying a significant amount of charge is launched along the wire, which travels as a unified pulse of 10s of ps duration with a velocity close to speed of light. The experimental capabilities and the analysis procedure of this specific type of proton probing technique are discussed.

Spatially resolved single crystal x-ray spectropolarimetry of wire array z-pinch plasmas.

PubMed

Wallace, M S; Haque, S; Neill, P; Pereira, N R; Presura, R

2018-01-01

A recently developed single-crystal x-ray spectropolarimeter has been used to record paired sets of polarization-dependent and axially resolved x-ray spectra emitted by wire array z-pinches. In this measurement, two internal planes inside a suitable crystal diffract the x-rays into two perpendicular directions that are normal to each other, thereby separating incident x-rays into their linearly polarized components. This paper gives considerations for fielding the instrument on extended sources. Results from extended sources are difficult to interpret because generally the incident x-rays are not separated properly by the crystal. This difficulty is mitigated by using a series of collimating slits to select incident x-rays that propagate in a plane of symmetry between the polarization-splitting planes. The resulting instrument and some of the spatially resolved polarized x-ray spectra recorded for a 1-MA aluminum wire array z-pinch at the Nevada Terawatt Facility at the University of Nevada, Reno will be presented.

Results from a tethered rocket experiment (Charge-2)

NASA Astrophysics Data System (ADS)

Kawashima, N.; Sasaki, S.; Oyama, K. I.; Hirao, K.; Obayashi, T.; Raitt, W. J.; White, A. B.; Williamson, P. R.; Banks, P. M.; Sharp, W. F.

A tethered payload experiment (Charge-2) was carried out as an international program between Japan and the USA using a NASA sounding rocket at White Sands Missile Range. The objective of the experiment was to perform a new type of active experiment in space by injecting an electron beam from a mother-daughter rocket system connected with a long tether wire. The electron beam with voltage and current up to 1 kV and 80 mA (nominal) was injected from the mother payload. An insulated conductive wire of 426 m length connected the two payloads, the longest tether system flown so far. The electron gun system and diagnostic instruments (plasma, optical, particle and wave) functioned correctly throughout the flight. The potential rise of the mother payload during the electron beam emission was measured with respect to the daughter payload. The beam trajectory was detected by a camera onboard the mother rocket. Wave generation and current induction in the wire during the beam emission were also studied.

Quantum-well exciton polariton emission from multi-quantum-well wire structures

NASA Astrophysics Data System (ADS)

Kohl, M.; Heitmann, D.; Grambow, P.; Ploog, K.

The radiative decay of quantum-well exciton (QWE) polaritons in microstructured Al0.3Ga0.7As - GaAs multi-quantum wells (MQW) has been studied by photoluminescence spectroscopy. Periodic wire structures with lateral periodicities a = 250-500 nm and lateral widths t = 100-200 nm have been fabricated by plasma etching. The thickness of the QWs was 13 nm. In the QW wire samples the free-exciton photoluminescence was strongly reduced and the QWE polariton emission was observed as a maximum peaked at a 3 meV higher energy than the free QWE transition. In samples which had only a microstructured cladding layer, the free-exciton photoluminescence was dominant in the spectrum and the QWE polariton emission was observed as a shoulder on the high-energy side of the free QWE transition. In addition, two transitions at the low energy side of the free QWE photoluminescence were present in the microstructured samples, which were related to etching induced states.

Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

NASA Astrophysics Data System (ADS)

Winands, G. J. J.; Liu, Z.; Pemen, A. J. M.; van Heesch, E. J. M.; Yan, K.; van Veldhuizen, E. M.

2006-07-01

In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh)-1. For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh)-1, still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second.

The exploding head syndrome.

PubMed

Green, M W

2001-06-01

This article reviews the features of an uncommon malady termed "the exploding head syndrome." Sufferers describe terrorizing attacks of a painless explosion within their head. Attacks tend to occur at the onset of sleep. The etiology of attacks is unknown, although they are considered to be benign. Treatment with clomipramine has been suggested, although most sufferers require only reassurance that the spells are benign in nature.

EIA: A splintering, exploding discipline with a massive new constituency

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

Johnson, Eric P., E-mail: ejohnson@ecosite.co.uk

2015-02-15

After serving 18 years as Editor-in-Chief of Environmental Impact Assessment Review, the author observes that the period 1997–2014, the discipline of EIA: splintered, exploded and saw the rise of the developing-world authors. Publishing has also changed, with shifts from quantity to quality, the rise of open access, and an ever-increasing shortage of reviewers.

Excimer laser produced plasmas in copper wire targets and water droplets

NASA Technical Reports Server (NTRS)

Song, Kyo-Dong; Alexander, D. R.

1994-01-01

Elastically scattered incident radiation (ESIR) from a copper wire target illuminated by a KrF laser pulse at lambda = 248 nm shows a dinstinct two-peak structure which is dependent on the incident energy. The time required to reach the critical electron density (n(sub c) approximately = 1.8 x 10(exp 22) electrons/cu cm) is estimated at 11 ns based on experimental results. Detailed ESIR characteristics for water have been reported previously by the authors. Initiation of the broadband emission for copper plasma begins at 6.5 +/- 1.45 ns after the arrival of the laser pulse. However, the broadband emission occurs at 11 +/- 0.36 ns for water. For a diatomic substance such as water, the electron energy rapidly dissipates due to dissociation of water molecules, which is absent in a monatomic species such as copper. When the energy falls below the excitation energy of the lowest electron state for water, it becomes a subexcitation electron. Lifetimes of the subexcited electrons to the vibrational states are estimated to be of the order of 10(exp -9) s. In addition, the ionization potential of copper (440-530 nm) is approximately 6 eV, which is about two times smaller than the 13 eV ionization potential reported for water. The higher ionization potential contributes to the longer observed delay time for plasma formation in water. After initiation, a longer time is required for copper plasma to reach its peak value. This time delay in reaching the maximum intensity is attributed to the energy loss during the interband transition in copper.

High Intensity Femtosecond XUV Pulse Interactions with Atomic Clusters: Final Report

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

Ditmire, Todd

We propose to expand our recent studies on the interactions of intense extreme ultraviolet (XUV) femtosecond pulses with atomic and molecular clusters. The work described follows directly from work performed under BES support for the past grant period. During this period we upgraded the THOR laser at UT Austin by replacing the regenerative amplifier with optical parametric amplification (OPA) using BBO crystals. This increased the contrast of the laser, the total laser energy to ~1.2 J , and decreased the pulse width to below 30 fs. We built a new all reflective XUV harmonic beam line into expanded lab space. This enabled an increase influence by a factor ofmore » 25 and an increase in the intensity by a factor of 50. The goal of the program proposed in this renewal is to extend this class of experiments to available higher XUV intensity and a greater range of wavelengths. In particular we plan to perform experiments to confirm our hypothesis about the origin of the high charge states in these exploding clusters, an effect which we ascribe to plasma continuum lowering (ionization potential depression) in a cluster nano-­plasma. To do this we will perform experiments in which XUV pulses of carefully chosen wavelength irradiate clusters composed of only low-Z atoms and clusters with a mixture of this low-­Z atom with higher Z atoms. The latter clusters will exhibit higher electron densities and will serve to lower the ionization potential further than in the clusters composed only of low Z atoms. This should have a significant effect on the charge states produced in the exploding cluster. We will also explore the transition of explosions in these XUV irradiated clusters from hydrodynamic expansion to Coulomb explosion. The work proposed here will explore clusters of a wider range of constituents, including clusters from solids. Experiments on clusters from solids will be enabled by development we performed during the past grant period in which we constructed and tested a cluster generator based on the Laser Ablation of Microparticles (LAM) method.« less

Pulmonary and heart diseases with inhalation of atmospheric pressure plasma flow

NASA Astrophysics Data System (ADS)

Hirata, Takamichi; Murata, Shigeru; Kishimoto, Takumi; Tsutsui, Chihiro; Kondo, Akane; Mori, Akira

2012-10-01

We examined blood pressure in the abdominal aorta of mini pig under plasma inhalation of atmospheric pressure plasma flow. The coaxial atmospheric pressure plasma source has a tungsten wire inside a glass capillary, that is surrounded by a grounded tubular electrode. Plasma was generated under the following conditions; applied voltage: 8 kVpp, frequency: 3 kHz, and helium (He) gas flow rate: 1 L/min. On the other hand, sphygmomanometry of a blood vessel proceeded using a device comprising a disposable force transducer, and a bedside monitor for simultaneous electrocardiography and signal pressure measurements. We directly measured Nitric oxide (NO) using a catheter-type NO sensor placed in the coronary sinus through an angiography catheter from the abdomen. Blood pressure decreased from 110/65 to 90/40 mm Hg in the animals in vivo under plasma inhalation. The NO concentration in the abdominal aorta like the blood pressure, reached a maximum value at about 40 s and then gradually decreased.

Quasi-discrete particle motion in an externally imposed, ordered structure in a dusty plasma at high magnetic field

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

Thomas, Edward, E-mail: etjr@auburn.edu; Konopka, Uwe; Lynch, Brian

Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas at magnetic fields up to 2.5 T where the electrons and ions are strongly magnetized. Plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper electrode supports a dual mesh consisting of #24 brass and #30 aluminum wire cloth. In this experiment, we study the formation of imposed ordered structures and particle dynamics as a function of magnetic field. Through observations of trapped particles and the quasi-discrete (i.e., “hopping”) motion of particles between the trapping locations, it is possible tomore » make a preliminary estimate of the potential structure that confines the particles to a grid structure in the plasma. This information is used to gain insight into the formation of the imposed grid pattern of the dust particles in the plasma.« less

A simple model for estimating a magnetic field in laser-driven coils

DOE PAGES

Fiksel, Gennady; Fox, William; Gao, Lan; ...

2016-09-26

Magnetic field generation by laser-driven coils is a promising way of magnetizing plasma in laboratory high-energy-density plasma experiments. A typical configuration consists of two electrodes—one electrode is irradiated with a high-intensity laser beam and another electrode collects charged particles from the expanding plasma. The two electrodes are separated by a narrow gap forming a capacitor-like configuration and are connected with a conducting wire-coil. The charge-separation in the expanding plasma builds up a potential difference between the electrodes that drives the electrical current in the coil. A magnetic field of tens to hundreds of Teslas generated inside the coil has beenmore » reported. This paper presents a simple model that estimates the magnetic field using simple assumptions. Lastly, the results are compared with the published experimental data.« less

The dynamic effects of metal vapour in gas metal arc welding

NASA Astrophysics Data System (ADS)

Haidar, Jawad

2010-04-01

Numerical simulations for the dynamic effects of metal vapour in gas metal arc welding (GMAW) suggest that vapour from the welding droplet at the tip of the welding wire has a significant influence on the plasma properties. It is found that for the evaporation rates calculated for arcs in pure argon, the dynamic effects of metal vapour markedly cool down the plasma in the central region of the arc, leading to the formation of a low temperature zone centred on the arc axis, in agreement with experimental measurements in the literature. Radiation effects, omitted in this paper, may produce further cooling of the plasma gas. The results highlight major deficiencies in the common approach to modelling the GMAW process and suggest that accurate description of GMAW must include the influence of metal vapour on the plasma.

Algebraic motion of vertically displacing plasmas

NASA Astrophysics Data System (ADS)

Pfefferlé, D.; Bhattacharjee, A.

2018-02-01

The vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to come in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear "sinking" behaviour shown to be algebraic and decelerating. The acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.

The locations of recent supernovae near the Sun from modelling (60)Fe transport.

PubMed

Breitschwerdt, D; Feige, J; Schulreich, M M; de Avillez, M A; Dettbarn, C; Fuchs, B

2016-04-07

The signature of (60)Fe in deep-sea crusts indicates that one or more supernovae exploded in the solar neighbourhood about 2.2 million years ago. Recent isotopic analysis is consistent with a core-collapse or electron-capture supernova that occurred 60 to 130 parsecs from the Sun. Moreover, peculiarities in the cosmic ray spectrum point to a nearby supernova about two million years ago. The Local Bubble of hot, diffuse plasma, in which the Solar System is embedded, originated from 14 to 20 supernovae within a moving group, whose surviving members are now in the Scorpius-Centaurus stellar association. Here we report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The (60)Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago at present-day galactic coordinates l = 327°, b = 11°, and the second-closest exploded about 1.5 million years ago at l = 343°, b = 25°, with masses of 9.2 and 8.8 times the solar mass, respectively. The remaining supernovae, which formed the Local Bubble, contribute to a smaller extent because they happened at larger distances and longer ago ((60)Fe has a half-life of 2.6 million years). There are uncertainties relating to the nucleosynthesis yields and the loss of (60)Fe during transport, but they do not influence the relative distribution of (60)Fe in the crust layers, and therefore our model reproduces the measured relative abundances very well.

Sparse and Large-Scale Learning Models and Algorithms for Mining Heterogeneous Big Data

ERIC Educational Resources Information Center

Cai, Xiao

2013-01-01

With the development of PC, internet as well as mobile devices, we are facing a data exploding era. On one hand, more and more features can be collected to describe the data, making the size of the data descriptor larger and larger. On the other hand, the number of data itself explodes and can be collected from multiple resources. When the data…

Magnetospheric Multiscale Mission Micrometeoroid/Orbital Debris Impacts

NASA Technical Reports Server (NTRS)

Williams, Trevor; Sedlak, Joseph; Shulman, Seth

2017-01-01

The MMS spacecraft are highly instrumented (accelerometers, star cameras, Sun sensors, science experiments for plasmas etc.). This presentation will discuss how data from these systems has allowed two micrometeoroid/orbital debris events to be studied: the Feb. 2, 2016 impact with an MMS4 shunt resistor, and the June 12, 2016 impact with an MMS4 wire boom.

Charging of moving surfaces by corona discharges sustained in air

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

Wang, Jun-Chieh, E-mail: junchwan@umich.edu; Kushner, Mark J., E-mail: mjkush@umich.edu; Zhang, Daihua, E-mail: dhzhang@tju.edu.cn

Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface ismore » continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.« less

Electrodynamic Tethers. 1: Power Generator in LEO. 2: Thrust for Propulsion and Power Storage

NASA Technical Reports Server (NTRS)

Mccoy, J. E.

1984-01-01

An electrodynamic tether consists of a long insulated wire in space whose orbital motion cuts across lines of magnetic flux to produce an induce voltage that in typical low orbits averages about 200 v/km. Such a system should be capable of generating substantial electrical power, at the expense of IXB drag acting on its orbital energy. If a reverse current is driven against the induced voltage, the system should act as a motor producing IXB thrust. A reference system was designed, capable of generating 20 KW of power into an electrical load located anywhere along the wire at the expense of 2.6N (20,000 J/sec) drag on the wire. In an ideal system, the conversion between mechanical and electrical energy would reach 100% efficiency. In the actual system part of the 20 KW is lost to internal resistance of the wire, plasma and ionosphere, while the drag force is increased by residual air drag. The 20 KW PMG system as designed is estimated to provide 18.7 KW net power to the load at total drag loss of 20.4 KJ/sec, or an overall efficiency of 92%. Similar systems using heavier wire appear capable of producing power levels in excess of 1 Megawatt at voltages of 2-4 KV, with conversion efficiency between mechanical and electrical power better than 95%. The hollow cathode based system should be readily reversible from generator to motor operation by driving a reverse current using onboard power.

Symmetric aluminum-wire arrays generate high-quality Z pinches at large array radii

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Mock, R. C.; Spielman, R. B.; Peterson, D. L.; Mosher, D.; Roderick, N. F.

1998-10-01

A Saturn-accelerator study of annular, aluminum-wire array, Z-pinch implosions, in the calculated high-wire-number plasma-shell regime [Phys. Rev. Lett. 77, 5063 (1996)], shows that the radiated x-ray pulse width increases from about 4 nsec to about 7 nsec, when the radius of the array is increased from 8.75 to 20 mm at a fixed array mass of 0.6 mg. Eulerian radiation- magnetohydrodynamic code (E-RMHC) simulations in the r-z plane suggest that this pulse-width increase with radius is due to the faster growth of the shell thickness (that arises from a two-stage development in the magnetic Rayleigh-Taylor instability) relative to the increase in the shell implosion velocity. Over the array radii explored, the measured peak total x-ray power of ˜40 TW and energy of ˜325 kJ show little change outside of a ±15% shot-to-shot fluctuation and are consistent with the E-RMHC simulations. Similarly, the measured peak K-shell (lines plus continuum) power of ˜8 TW and energy of ˜70 kJ show little change with radius. The minimal change in K-shell yield is in agreement with simple K-shell radiation scaling models that assume a fixed radial compression for all initial array radii. These results suggest that the improved uniformity provided by the large number of wires in the initial array reduces the disruptive effects of the Rayleigh-Taylor instability observed in small-wire-number imploding loads.

Carbon nanospikes grown on metal wires as microelectrode sensors for dopamine

DOE PAGES

Zestos, Alexander G.; Yang, Cheng; Jacobs, Christopher B.; ...

2015-09-14

Carbon nanomaterials are advantageous as electrodes for neurotransmitter detection, but the difficulty of nanomaterials deposition on electrode substrates limits the reproducibility and future applications. In our study, we used plasma enhanced chemical vapor deposition (PECVD) to directly grow a thin layer of carbon nanospikes (CNS) on cylindrical metal substrates. No catalyst is required and the CNS surface coverage is uniform over the cylindrical metal substrate. We characterized the CNS growth on several metallic substrates including tantalum, niobium, palladium, and nickel wires. Using fast-scan cyclic voltammetry (FSCV), bare metal wires could not detect 1 mu M dopamine while carbon nanospike coatedmore » wires could. Moreover, the highest sensitivity and optimized S/N ratio was recorded from carbon nanospike-tantalum (CNS-Ta) microwires grown for 7.5 minutes, which had a LOD of 8 +/- 2 nM for dopamine with FSCV. CNS-Ta microelectrodes were more reversible and had a smaller Delta E-p for dopamine than carbon-fiber microelectrodes, suggesting faster electron transfer kinetics. The kinetics of dopamine redox were adsorption controlled at CNS-Ta microelectrodes and repeated electrochemical measurements displayed stability for up to ten hours in vitro and over a ten day period as well. The oxidation potential was significantly different for ascorbic acid and uric acid compared to dopamine. Finally, growing carbon nanospikes on metal wires is a promising method to produce uniformly-coated, carbon nanostructured cylindrical microelectrodes for sensitive dopamine detection.« less

Microstructural studies of 35 degrees C copper Ni-Ti orthodontic wire and TEM confirmation of low-temperature martensite transformation.

PubMed

Brantley, William A; Guo, Wenhua; Clark, William A T; Iijima, Masahiro

2008-02-01

Previous temperature-modulated differential scanning calorimetry (TMDSC) study of nickel-titanium orthodontic wires revealed a large exothermic low-temperature peak that was attributed to transformation within martensitic NiTi. The purpose of this study was to use transmission electron microscopy (TEM) to verify this phase transformation in a clinically popular nickel-titanium wire, identify its mechanism and confirm other phase transformations found by TMDSC, and to provide detailed information about the microstructure of this wire. The 35 degrees C Copper nickel-titanium wire (Ormco) with cross-section dimensions of 0.016 in. x 0.022 in. used in the earlier TMDSC investigation was selected. Foils were prepared for TEM analyses by mechanical grinding, polishing, dimpling, ion milling and plasma cleaning. Standard bright-field and dark-field TEM images were obtained, along with convergent-beam electron diffraction patterns. A cryo-stage with the electron microscope (Phillips CM 200) permitted the specimen to be observed at -187, -45, and 50 degrees C, as well as at room temperature. Microstructures were also observed with an optical microscope and a scanning electron microscope. Room temperature microstructures had randomly oriented, elongated grains that were twinned. Electron diffraction patterns confirmed that phase transformations took place over temperature ranges previously found by TMDSC. TEM observations revealed a high dislocation density and fine-scale oxide particles, and that twinning is the mechanism for the low-temperature transformation in martensitic NiTi. TEM confirmed the low-temperature peak and other phase transformations observed by TMDSC, and revealed that twinning in martensite is the mechanism for the low-temperature peak. The high dislocation density and fine-scale oxide particles in the microstructure are the result of the wire manufacturing process.

Magnetic-particles-composed wire structures produced by pulsed laser deposition in a magnetic field

NASA Astrophysics Data System (ADS)

Nikov, Ru; Dikovska, A.; Nedyalkov, N.; Atanasov, P.

2018-03-01

We demonstrate the possibility to fabricate wire structures composed by arranged magnetic particles using pulsed laser deposition (PLD) in the presence of a magnetic field. Ablation of Ni and Co targets was performed in air by nanosecond laser pulses delivered by a Nd:YAG laser system oscillating at 355 nm. Due to the high density of the ambient, particles and clusters were formed by condensation in the plasma plume close to the target. The strong deceleration of the ablated material under these conditions further benefited the efficiency of applying a magnetic field to the plume. We also studied the effect of the target-to-substrate distance and the ambient pressure on the morphology of the deposited structures.

Ocular injuries from exploding glass-bottled Coca-Cola® drinks in Port Harcourt, Nigeria

PubMed Central

Pedro-Egbe, Chinyere Nnenne; Ejimadu, Chibuike Sydney; Nwachukwu, Henrietta

2011-01-01

Background: Eye injuries and subsequent loss of vision from the glass and caps of exploding pressurized bottled drinks have been well reported, and as a result most developed countries now use mainly plastic bottles. In Nigeria, however, most drinks are still sold in glass bottles and ocular injuries from this source are therefore not uncommon. Aim: To retrospectively analyze ocular injuries resulting from exploding glass-bottled Coca-Cola® and propose ways of eliminating such injuries in future. Setting: Eye Clinic, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. Materials and methods: The medical records of all cases of ocular injury that presented at the Eye Clinic of the University of Port Harcourt Teaching Hospital over a 5-year period (January 2006 to December 2010) were retrieved and relevant data including age, sex, occupation, events surrounding bottle explosion, and type of ocular injury sustained were extracted. Results: A total of 426 cases of ocular injuries was seen during the period under review. There were 335 (78.6%) males and 91 (21.4%) females. Six patients had ocular injury from exploding glass-bottled Coca-Cola®, giving an incidence of 1.4%. The presenting visual acuities (VA) were light perception (2 cases), counting fingers (2 cases), and 1 VA of 6/24 and 1 VA of 6/12. There were 4 (66.7%) cases of corneoscleral laceration with uveal prolapse and 1 case of total hyphema. Conclusion: Because pressurized glass-bottles can explode with normal handling, legislation to ban the use of glass containers for bottling carbonated drinks will go a long way to reducing ocular morbidity from this source. Plastic bottles should be introduced as an alternative. PMID:21629570

Revival of the fittest: exploding core-collapse supernovae from 12 to 25 M⊙

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

Vartanyan, David; Burrows, Adam; Radice, David

Here, we present results of 2D axisymmetric core-collapse supernova simulations, employing the FORNAX code, of nine progenitor models spanning 12 to 25 M⊙. Four of the models explode with inelastic scattering off electrons and neutrons as well as the many-body correction to neutrino-nucleon scattering opacities. We show that these four models feature sharp Si–O interfaces in their density profiles, and that the corresponding dip in density reduces the accretion rate around the stalled shock and prompts explosion. The non-exploding models lack such a steep feature, highlighting the Si–O interface as one key to explosion. Furthermore, we show that all ofmore » the non-exploding models can be nudged to explosion with modest changes to macrophysical inputs, including moderate rotation and perturbations to infall velocities, as well as to microphysical inputs, including reasonable changes to neutrino-nucleon interaction rates, suggesting that all the models are perhaps close to criticality. Exploding models have energies of a few × 10 50 erg at the end of our simulation, and are rising, emphasizing the need to continue these simulations over larger grids and for longer times to reproduce the energies seen in nature. Morphology of the explosion contributes to the explosion energy, with more isotropic ejecta producing larger explosion energies. We do not find evidence for the Lepton-number Emission Self-sustained Asymmetry. Finally, we look at proto-neutron star (PNS) properties and explore the role of dimension in our simulations. We find that convection in the PNS produces larger PNS radii as well as greater ‘ν μ’ luminosities in 2D compared to 1D.« less

Revival of the fittest: exploding core-collapse supernovae from 12 to 25 M⊙

DOE PAGES

Vartanyan, David; Burrows, Adam; Radice, David; ...

2018-03-28

Here, we present results of 2D axisymmetric core-collapse supernova simulations, employing the FORNAX code, of nine progenitor models spanning 12 to 25 M⊙. Four of the models explode with inelastic scattering off electrons and neutrons as well as the many-body correction to neutrino-nucleon scattering opacities. We show that these four models feature sharp Si–O interfaces in their density profiles, and that the corresponding dip in density reduces the accretion rate around the stalled shock and prompts explosion. The non-exploding models lack such a steep feature, highlighting the Si–O interface as one key to explosion. Furthermore, we show that all ofmore » the non-exploding models can be nudged to explosion with modest changes to macrophysical inputs, including moderate rotation and perturbations to infall velocities, as well as to microphysical inputs, including reasonable changes to neutrino-nucleon interaction rates, suggesting that all the models are perhaps close to criticality. Exploding models have energies of a few × 10 50 erg at the end of our simulation, and are rising, emphasizing the need to continue these simulations over larger grids and for longer times to reproduce the energies seen in nature. Morphology of the explosion contributes to the explosion energy, with more isotropic ejecta producing larger explosion energies. We do not find evidence for the Lepton-number Emission Self-sustained Asymmetry. Finally, we look at proto-neutron star (PNS) properties and explore the role of dimension in our simulations. We find that convection in the PNS produces larger PNS radii as well as greater ‘ν μ’ luminosities in 2D compared to 1D.« less

Ocular injuries from exploding glass-bottled Coca-Cola® drinks in Port Harcourt, Nigeria.

PubMed

Pedro-Egbe, Chinyere Nnenne; Ejimadu, Chibuike Sydney; Nwachukwu, Henrietta

2011-01-01

Eye injuries and subsequent loss of vision from the glass and caps of exploding pressurized bottled drinks have been well reported, and as a result most developed countries now use mainly plastic bottles. In Nigeria, however, most drinks are still sold in glass bottles and ocular injuries from this source are therefore not uncommon. To retrospectively analyze ocular injuries resulting from exploding glass-bottled Coca-Cola® and propose ways of eliminating such injuries in future. Eye Clinic, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. The medical records of all cases of ocular injury that presented at the Eye Clinic of the University of Port Harcourt Teaching Hospital over a 5-year period (January 2006 to December 2010) were retrieved and relevant data including age, sex, occupation, events surrounding bottle explosion, and type of ocular injury sustained were extracted. A total of 426 cases of ocular injuries was seen during the period under review. There were 335 (78.6%) males and 91 (21.4%) females. Six patients had ocular injury from exploding glass-bottled Coca-Cola®, giving an incidence of 1.4%. The presenting visual acuities (VA) were light perception (2 cases), counting fingers (2 cases), and 1 VA of 6/24 and 1 VA of 6/12. There were 4 (66.7%) cases of corneoscleral laceration with uveal prolapse and 1 case of total hyphema. Because pressurized glass-bottles can explode with normal handling, legislation to ban the use of glass containers for bottling carbonated drinks will go a long way to reducing ocular morbidity from this source. Plastic bottles should be introduced as an alternative.

XMM-Newton Proposal 03039101

NASA Astrophysics Data System (ADS)

Hernanz, Margarita

2004-10-01

Two recent galactic novae, V2487 Oph 1998 and V4633 Sgr 1998, have been detec- ted in both soft and hard X-rays with XMM. V2487 Oph showed an iron fluores- cent line only 2.7 yrs after its explosion, a clear signature of the very fast recovery of accretion, and V4633 Sgr displayed hard X-ray emission not clearly attributable to shocked ejecta or accretion. Longer observations are needed to do accurate timing and high resolution spectroscopy, essential to determine the main properties of the underlying cataclysmic variable in V2487 Oph (first nova seen in X-rays prior and after exploding) and to disentangle the origin of the hard X-rays from V4633 Sgr, through an analysis of the chemical compo- sition of the emitting thermal plasma, solar if accretion, non solar if ejecta.

Transportation properties of a high-current magnetically insulated transmission line and dynamics of the electrode plasma

NASA Astrophysics Data System (ADS)

Anan'ev, S. S.; Bakshaev, Yu. L.; Bartov, A. V.; Blinov, P. I.; Dan'ko, S. A.; Zhuzhunashvili, A. I.; Kazakov, E. D.; Kalinin, Yu. G.; Kingsep, A. S.; Korolev, V. D.; Mizhiritskii, V. I.; Smirnov, V. P.; Tkachenko, S. I.; Chernenko, A. S.

2008-07-01

Results are presented from experimental studies of a section of a magnetically insulated transmission line (MITL) with a current density of up to 500 MA/cm2 and linear current density of up to 7 MA/cm (the parameters close to those in a fast-Z-pinch-driven fusion reactor projected at Sandia Laboratories). The experiments were performed in the S-300 facility (3 MA, 0.15 Ω, 100 ns). At high linear current densities, the surface of the ohmically heated MITL electrode can explode and a plasma layer can form near the electrode surface. As a result, the MITL can lose its transmission properties due to the shunting of the vacuum gap by the plasma produced. In this series of experiments, the dynamics of the electrode plasma and the dependence of the transmission properties of the MITL on the material and cleanness of the electrode surface were studied. It is shown experimentally that, when the current with a linear density of up to 7 MA/cm begins to flow along a model MITL, the input and output currents differ by less than 10% over a time interval of up to 230 ns for nickel electrodes and up to 350 ns for a line with a gold central electrode. No effect of the oil film present on the electrode surface on the loss of the transmission properties of the line was observed. It is also shown that electron losses insignificantly contribute to the total current balance. The experimental results are compared with calculations of the electrode explosion and the subsequent expansion of the plasma layer. A conclusion is made that the life-time of the model MITL satisfies the requirements imposed on the transmission lines intended for use in the projected thermonuclear reactor.

On Floating Potential of Emissive Probes in a Partially-Magnetized Plasma

NASA Astrophysics Data System (ADS)

Raitses, Yevgeny; Kraus, Brian

2016-10-01

We compare measurements of plasma potential in a cross-field Penning discharge from two probes: swept biased Langmuir probe and floating emissive probe. The plasma potential was deduced from the first derivative of the Langmuir probe characteristic. In previous studies, the emissive and swept biased probes were placed at the channel exit of a Hall thruster (HT). Measurements showed that the emissive probe floats below the plasma potential, in agreement with conventional theories. However, recent measurements in the Penning discharge indicate a floating potential of a strongly-emitting hot probe above the plasma potential. In both probe applications, xenon plasmas have magnetized electrons and non-magnetized ions with similar plasma densities (1010 - 1011 cm-3) . Though their electron temperatures differ by an order of magnitude (Penning 5 eV, HT 50 eV), this difference cannot explain the difference in measurement values of the hot floating potential because both temperatures are much higher than the emitting wire. In this work, we investigate how the ion velocity and other plasma parameters affect this discrepancy between probe measurements of the plasma potential. This work was supported by DOE contract DE-AC02-09CH11466.

Proton acceleration to above 5.5 MeV by interaction of 1017 W/cm2 laser pulse with H2O nano-wire targets

NASA Astrophysics Data System (ADS)

Schleifer, E.; Bruner, N.; Eisenmann, S.; Botton, M.; Pikuz, S. A., Jr.; Faenov, A. Y.; Gordon, D.; Zigler, A.

2011-05-01

Compact sources of high energy protons (50-500MeV) are expected to be key technology in a wide range of scientific applications 1-8. Particularly promising is the target normal sheah acceleration (TNSA) scheme 9,10, holding record level of 67MeV protons generated by a peta-Watt laser 11. In general, laser intensity exceeding 1018 W/cm2 is required to produce MeV level protons. Enhancing the energy of generated protons using compact laser sources is very attractive task nowadays. Recently, nano-scale targets were used to accelerate ions 12,13. Here we report on the first generation of 5.5-7.5MeV protons by modest laser intensities (4.5 × 1017 W/cm2) interacting with H2O nano-wires (snow) deposited on a Sapphire substrate. In this setup, the plasma near the tip of the nano-wire is subject to locally enhanced laser intensity with high spatial gradients, and confined charge separation is obtained. Electrostatic fields of extremely high intensities are produced, and protons are accelerated to MeV-level energies. Nano-wire engineered targets will relax the demand of peak energy from laser based sources.

Grazing incidence extreme ultraviolet spectrometer fielded with time resolution in a hostile z-pinch environment.

PubMed

Williamson, K M; Kantsyrev, V L; Safronova, A S; Wilcox, P G; Cline, W; Batie, S; LeGalloudec, B; Nalajala, V; Astanovitsky, A

2011-09-01

This recently developed diagnostic was designed to allow for time-gated spectroscopic study of the EUV radiation (4 nm < λ < 15 nm) present during harsh wire array z-pinch implosions. The spectrometer utilizes a 25 μm slit, an array of 3 spherical blazed gratings at grazing incidence, and a microchannel plate (MCP) detector placed in an off-Rowland position. Each grating is positioned such that its diffracted radiation is cast over two of the six total independently timed frames of the MCP. The off-Rowland configuration allows for a much greater spectral density on the imaging plate but only focuses at one wavelength per grating. The focal wavelengths are chosen for their diagnostic significance. Testing was conducted at the Zebra pulsed-power generator (1 MA, 100 ns risetime) at the University of Nevada, Reno on a series of wire array z-pinch loads. Within this harsh z-pinch environment, radiation yields routinely exceed 20 kJ in the EUV and soft x-ray. There are also strong mechanical shocks, high velocity debris, sudden vacuum changes during operation, energic ion beams, and hard x-ray radiation in excess of 50 keV. The spectra obtained from the precursor plasma of an Al double planar wire array contained lines of Al IX and AlX ions indicating a temperature near 60 eV during precursor formation. Detailed results will be presented showing the fielding specifications and the techniques used to extract important plasma parameters using this spectrometer. © 2011 American Institute of Physics

Competency Development Detonator Development and Design

DTIC Science & Technology

2007-09-01

required. Exploding foil initiators ( EFI or Slapper) - The benefits of using an EFI is that the metal bridge is separated from the explosive, the explosive...to the materials ignition temperature to begin a burning reaction that propagates to the next material in the initiator . Exploding bridgewire (EBW...principles "* Initiation capabilities of the MEMS scale detonator DETONATOR BACKGROUND In a typical detonator, an explosive train is used. The explosive train

Findings from NASA's 2015-2017 Electric Sail Investigations

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce. M.

2017-01-01

Electric Sail (E-Sail) propulsion systems will enable scientific spacecraft to obtain velocities of up to 10 astronomical units per year without expending any on-board propellant. The E-Sail propulsion is created from the interaction of a spacecraft's positively charged multi-kilometer-length conductor/s with protons that are present in the naturally occurring hypersonic solar wind. The protons are deflected via natural electrostatic repulsion forces from the Debye sheath that is formed around a charged wire in space, and this deflection of protons creates thrust or propulsion in the opposite direction. It is envisioned that this E-Sail propulsion system can provide propulsion throughout the solar system and to the heliosphere and beyond. Consistent with the concept of a "sail," no propellant is needed as electrostatic repulsion interactions between the naturally occurring solar wind protons and a positively charged wire creates the propulsion. The basic principle on which the Electric Sail operates is the exchange of momentum between an "electric sail" and solar wind, which continually flows radially away from the sun at speeds ranging from 300 to 700 kilometers per second. The "sail" consists of an array of long, charged wires which extend radially outward 10 to 30 kilometers from a slowly rotating spacecraft. Momentum is transferred from the solar wind to the array through the deflection of the positively charged solar wind protons by a high voltage potential applied to the wires. The thrust generated by an E-Sail is proportional to the area of the sail, which is given by the product of the total length of the wires and the effective wire diameter. The wire is approximately 0.1 millimeters in diameter. However, the effective diameter is determined by the distance the applied electric potential penetrates into space around the wire (on the order of 10 meters at 1 astronomical unit). As a result, the effective area over which protons are repelled is proportional to the size of the region of electric potential, or the plasma sheath region, surround the wires of the array. A large sheath is, therefore, beneficial to the generation of thrust. However, this benefit must be balanced with the additional fact that electron collection is proportional to sheath size. Electrons collected by the wire array must be injected back into the solar wind in order to maintain the potential on the wires - which requires power. The primary power requirement for E-Sail operation is, therefore, also proportional to sheath size.

Supernova SN 2011fe from an exploding carbon-oxygen white dwarf star.

PubMed

Nugent, Peter E; Sullivan, Mark; Cenko, S Bradley; Thomas, Rollin C; Kasen, Daniel; Howell, D Andrew; Bersier, David; Bloom, Joshua S; Kulkarni, S R; Kandrashoff, Michael T; Filippenko, Alexei V; Silverman, Jeffrey M; Marcy, Geoffrey W; Howard, Andrew W; Isaacson, Howard T; Maguire, Kate; Suzuki, Nao; Tarlton, James E; Pan, Yen-Chen; Bildsten, Lars; Fulton, Benjamin J; Parrent, Jerod T; Sand, David; Podsiadlowski, Philipp; Bianco, Federica B; Dilday, Benjamin; Graham, Melissa L; Lyman, Joe; James, Phil; Kasliwal, Mansi M; Law, Nicholas M; Quimby, Robert M; Hook, Isobel M; Walker, Emma S; Mazzali, Paolo; Pian, Elena; Ofek, Eran O; Gal-Yam, Avishay; Poznanski, Dovi

2011-12-14

Type Ia supernovae have been used empirically as 'standard candles' to demonstrate the acceleration of the expansion of the Universe even though fundamental details, such as the nature of their progenitor systems and how the stars explode, remain a mystery. There is consensus that a white dwarf star explodes after accreting matter in a binary system, but the secondary body could be anything from a main-sequence star to a red giant, or even another white dwarf. This uncertainty stems from the fact that no recent type Ia supernova has been discovered close enough to Earth to detect the stars before explosion. Here we report early observations of supernova SN 2011fe in the galaxy M101 at a distance from Earth of 6.4 megaparsecs. We find that the exploding star was probably a carbon-oxygen white dwarf, and from the lack of an early shock we conclude that the companion was probably a main-sequence star. Early spectroscopy shows high-velocity oxygen that slows rapidly, on a timescale of hours, and extensive mixing of newly synthesized intermediate-mass elements in the outermost layers of the supernova. A companion paper uses pre-explosion images to rule out luminous red giants and most helium stars as companions to the progenitor.

Exploring the universe through discovery science on NIF

NASA Astrophysics Data System (ADS)

Remington, Bruce

2016-10-01

New regimes of science are being experimentally studied at high energy density facilities around the world, spanning drive energies from microjoules to megajoules, and time scales from femtoseconds to microseconds. The ability to shock and ramp compress samples to very high pressures and densities allows new states of matter relevant to planetary and stellar interiors to be studied. Shock driven hydrodynamic instabilities evolving into turbulent flows relevant to the dynamics of exploding stars (such as supernovae), accreting compact objects (such as white dwarfs, neutron stars, and black holes), and planetary formation dynamics are being probed. The dynamics of magnetized plasmas relevant to astrophysics, both in collisional and collisionless systems, are starting to be studied. High temperature, high velocity interacting flows are being probed for evidence of astrophysical collisionless shock formation, the turbulent magnetic dynamo effect, magnetic reconnection, and particle acceleration. And new results from thermonuclear reactions in hot dense plasmas relevant to stellar and big bang nucleosynthesis are starting to emerge. A selection of examples providing a compelling vision for frontier science on NIF in the coming decade will be presented. This work was performed under the auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Magneto Rayleigh-Taylor, Sausage, and Kink Instability Experiments on a MegaAmpere Linear Transformer Driver

NASA Astrophysics Data System (ADS)

Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Gilgenbach, R. M.; Lau, Y. Y.; Weis, M. R.; Zhang, P.

2015-11-01

At the Michigan Accelerator for Inductive Z-Pinch Experiments (MAIZE) facility, a 1-MA Linear Transformer Driver (LTD) is being used to deliver 500-600 kA to cylindrical liners in order to study the magneto Rayleigh-Taylor (MRT), sausage, and kink instabilities in imploding and exploding Al plasmas. The liners studied in this experiment had thicknesses of 400 nm to 30 μm, heights of 1-2 cm, and diameters of 1-6 mm. The plasmas were imaged using 4-time-frame, laser shadowgraphy and shearing-interferometry at 532 nm. For imploding liners, the measured acceleration was found to be less than predicted from the current pulse, indicating significant diffusion of the azimuthal magnetic field. A simple experimental configuration is presented for ``end-on'' laser probing in the r- θ plane in order to study the interior of the liner. Finally, the effects of axial magnetic fields are determined by modifying the return current posts and incorporating external coils. Experimental growth rates are determined and discussed. This work was supported by DOE award DE-SC0012328. S.G. Patel supported by Sandia National Labs. D.A. Yager was supported by NSF fellowship grant DGE 1256260.

Exploring the universe through Discovery Science on NIF

NASA Astrophysics Data System (ADS)

Remington, Bruce

2017-10-01

New regimes of science are being experimentally studied at high energy density facilities around the world, spanning drive energies from microjoules to megajoules, and time scales from femtoseconds to microseconds. The ability to shock and ramp compress samples to very high pressures and densities allows new states of matter relevant to planetary and stellar interiors to be studied. Shock driven hydrodynamic instabilities evolving into turbulent flows relevant to the dynamics of exploding stars (such as supernovae), accreting compact objects (such as white dwarfs, neutron stars, and black holes), and planetary formation dynamics (relevant to the exoplanets) are being probed. The dynamics of magnetized plasmas relevant to astrophysics, both in collisional and collisionless systems, are starting to be studied. High temperature, high velocity interacting flows are being probed for evidence of astrophysical collisionless shock formation, the turbulent magnetic dynamo effect, magnetic reconnection, and particle acceleration. And new results from thermonuclear reactions in hot dense plasmas relevant to stellar and big bang nucleosynthesis are starting to emerge. A selection of examples of frontier research through NIF Discovery Science in the coming decade will be presented. This work was performed under the auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Electrically controlled wire-channel GaN/AlGaN transistor for terahertz plasma applications

NASA Astrophysics Data System (ADS)

Cywiński, G.; Yahniuk, I.; Kruszewski, P.; Grabowski, M.; Nowakowski-Szkudlarek, K.; Prystawko, P.; Sai, P.; Knap, W.; Simin, G. S.; Rumyantsev, S. L.

2018-03-01

We report on a design of fin-shaped channel GaN/AlGaN field-effect transistors developed for studying resonant terahertz plasma oscillations. Unlike common two dimensional FinFET transistor design, the gates were deposited only to the sides of the two dimensional electron gas channel, i.e., metal layers were not deposited on the top of the AlGaN. This side gate configuration allowed us to electrically control the conductivity of the channel by changing its width while keeping the carrier density and mobility virtually unchanged. Computer simulations and analytical model describe well the general shape of the characteristics. The side gate control of the channel width of these transistors allowed us to eliminate the so-called oblique plasma wave modes and paves the way towards future terahertz detectors and emitters using high quality factor plasma wave resonances.

Spectroscopic studies of GTA welding plasmas. Temperature calculation and dilution measurement

NASA Astrophysics Data System (ADS)

Lacroix, D.; Boudot, C.; Jeandel, G.

1999-10-01

A spectroscopic study of the GTAW plasma-plume created during the welding of stainless steel and other materials (iron, nickel and chromium) has been carried out. The spectra of these plasmas have been studied for several welding parameters. Temperature calculations are based on the observation of relative intensities and shapes of the emission peaks. We assume that the plasma is in local thermal equilibrium. The temperature is calculated with the Boltzmann plot method from twelve iron emission lines (in the range 368 385 nm): it varies between 9650 and 12 100 K. Dilution experiments have been carried out. We checked the mixing of metals: during welding of two different metallic plates and during welding with an Inconel wire. Dilution is monitored following the intensity of some characteristic emission lines (chromium and nickel). Comparison of spectroscopic results and metallographic ones is made.

Post-breakdown secondary discharges at the electrode/dielectric interface of a cylindrical barrier discharge

NASA Astrophysics Data System (ADS)

Carman, Robert; Ward, Barry; Kane, Deborah

2011-10-01

The electrical breakdown characteristics of a double-walled cylindrical dielectric barrier discharge (DBD) lamp with a neon buffer gas under pulsed voltage excitation have been investigated. Following the formation of plasma in the main discharge gap, we have observed secondary breakdown phenomena at the inner and outer mesh electrode/dielectric interfaces under specific operating conditions. Plasma formation at these interfaces is investigated by monitoring the Ozone production rate in controlled flows of ultra high purity oxygen together with the overall electrical voltage-charge characteristics of the lamp. The results show that this secondary breakdown only occurs after the main discharge plasma has been established, and that significant electrical power may be dissipated in generating these spurious secondary plasmas. The results are important with regards to optimising the design and identifying efficient operating regimes of DBD based devices that employ mesh-type or wire/strip electrodes.

Quasi-thermal noise spectroscopy: The art and the practice

NASA Astrophysics Data System (ADS)

Meyer-Vernet, N.; Issautier, K.; Moncuquet, M.

2017-08-01

Quasi-thermal noise spectroscopy is an efficient tool for measuring in situ macroscopic plasma properties in space, using a passive wave receiver at the ports of an electric antenna. This technique was pioneered on spinning spacecraft carrying very long dipole antennas in the interplanetary medium—like ISEE-3 and Ulysses—whose geometry approached a "theoretician's dream." The technique has been extended to other instruments in various types of plasmas on board different spacecraft and will be implemented on several missions in the near future. Such extensions require different theoretical modelizations, involving magnetized, drifting, or dusty plasmas with various particle velocity distributions and antennas being shorter, biased, or made of unequal wires. We give new analytical approximations of the plasma quasi-thermal noise (QTN) and study how the constraints of the real world in space can (or cannot) be compatible with plasma detection by QTN spectroscopy. We consider applications to the missions Wind, Cassini, BepiColombo, Solar Orbiter, and Parker Solar Probe.

A gas-puff-driven theta pinch for plasma-surface interaction studies

NASA Astrophysics Data System (ADS)

Jung, Soonwook; Kesler, Leigh; Yun, Hyun-Ho; Curreli, Davide; Andruczyk, Daniel; Ruzic, David

2012-10-01

DEVeX is a theta pinch device used to investigate fusion-related material interaction such as vapor shielding and ICRF antenna interactions with plasma-pulses in a laboratory setting. The simulator is required to produce high heat-flux plasma enough to induce temperature gradient high enough to study extreme conditions happened in a plasma fusion reactor. In order to achieve it, DEVeX is reconfigured to be combined with gas puff system as gas puffing may reduce heat flux loss resulting from collisions with neutral. A gas puff system as well as a conical gas nozzle is manufactured and several diagnostics including hot wire anemometer and fast ionization gauge are carried out to quantitatively estimate the supersonic flow of gas. Energy deposited on the target for gas puffing and static-filled conditions is measured with thermocouples and its application to TELS, an innovative concept utilizing a thermoelectric-driven liquid metal flow for plasma facing component, is discussed.

Effect of plasma actuator and splitter plate on drag coefficient of a circular cylinder

NASA Astrophysics Data System (ADS)

Akbıyık, Hürrem; Erkan Akansu, Yahya; Yavuz, Hakan; Ertuğrul Bay, Ahmet

2016-03-01

In this paper, an experimental study on flow control around a circular cylinder with splitter plate and plasma actuator is investigated. The study is performed in wind tunnel for Reynolds numbers at 4000 and 8000. The wake region of circular cylinder with a splitter plate is analyzed at different angles between 0 and 180 degrees. In this the study, not only plasma actuators are activated but also splitter plate is placed behind the cylinder. A couple electrodes are mounted on circular cylinder at ±90 degrees. Also, flow visualization is achieved by using smoke wire method. Drag coefficient of the circular cylinder with splitter plate and the plasma actuator are obtained for different angles and compared with the plain circular cylinder. While attack angle is 0 degree, drag coefficient is decreased about 20% by using the splitter plate behind the circular cylinder. However, when the plasma actuators are activated, the improvement of the drag reduction is measured to be 50%.

Isolation Mounting for Charge-Coupled Devices

NASA Technical Reports Server (NTRS)

Goss, W. C.; Salomon, P. M.

1985-01-01

CCD's suspended by wires under tension. Remote thermoelectric cooling of charge coupled device allows vibration isolating mounting of CCD assembly alone, without having to suspend entire mass and bulk of thermoelectric module. Mounting hardware simple and light. Developed for charge-coupled devices (CCD's) in infrared telescope support adaptable to sensors in variety of environments, e.g., sensors in nuclear reactors, engine exhausts and plasma chambers.

Automated Welding System

NASA Technical Reports Server (NTRS)

Bayless, E. O.; Lawless, K. G.; Kurgan, C.; Nunes, A. C.; Graham, B. F.; Hoffman, D.; Jones, C. S.; Shepard, R.

1993-01-01

Fully automated variable-polarity plasma arc VPPA welding system developed at Marshall Space Flight Center. System eliminates defects caused by human error. Integrates many sensors with mathematical model of the weld and computer-controlled welding equipment. Sensors provide real-time information on geometry of weld bead, location of weld joint, and wire-feed entry. Mathematical model relates geometry of weld to critical parameters of welding process.

Strategic Alliances: Making a Difference One Warfighter At a Time

DTIC Science & Technology

2011-03-12

Prototype Integration Planning Machining / CNC / Metals Welding Assembly / Paint Integration •Field-Experienced Veterans •Component, Subsystems...Wiring Harness •CAD/CAM CNC Programming •Quick reaction of parts - CNC , Lathes, Mills, Water Jet/Laser Cutting Design •Mechanical, Electrical...DEFORMATION RESISTANCE WELDING • Tubular Structural welding, Light weight structures COMBINED PLASMA -MIG ARC WELDING • Faster than any other

The Heliopause Electrostatic Rapid Transit System (HERTS) Design, Trades, and Analyses Performed in the First Year of a Two Year Investigation

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce M.

2016-01-01

The Heliopause Electrostatic Rapid Transit System (HERTS)1 was one of the seven total Phase II NASA Innovative Advanced Concepts (NIAC) that was down-selected in 2015 for continued funding and research. In Phase I we learned that a spacecraft propelled by an Electric Sail (E-Sail) can travel great astronomical distances, such as to the Heliopause region of the solar system (approx.100 to 120 AU) in approximately one quarter of the time (10 years) versus the time it took the Voyager spacecraft launched in 1977 (36 years). The current work within the Phase II NIAC effort builds upon the work that was done in the Phase I NIAC and is focused on: 1) Testing of plasma interaction with a charged wire in a unique MSFC test chamber, 2) Development of a Particle-in-Cell (PIC) models that are validated in the plasma testing and used to extrapolate to the E-Sail propulsion system design. 3) Further down select of a wire deployment and control approach from those narrowed down in the Phase I effort. This paper will document the findings to date (June, 2016) of the above focused areas.

Preliminary investigation on the use of low current pulsed power Z-pinch plasma devices for the study of early stage plasma instabilities

NASA Astrophysics Data System (ADS)

Kaselouris, E.; Dimitriou, V.; Fitilis, I.; Skoulakis, A.; Koundourakis, G.; Clark, E. L.; Chatzakis, J.; Bakarezos, Μ; Nikolos, I. K.; Papadogiannis, N. A.; Tatarakis, M.

2018-01-01

This article addresses key features for the implementation of low current pulsed power plasma devices for the study of matter dynamics from the solid to the plasma phase. The renewed interest in such low current plasma devices lies in the need to investigate methods for the mitigation of prompt seeding mechanisms for the generation of plasma instabilities. The low current when driven into thick wires (skin effect mode) allows for the simultaneous existence of all phases of matter from solid to plasma. Such studies are important for the concept of inertial confinement fusion where the mitigation of the instability seeding mechanisms arising from the very early moments within the target’s heating is of crucial importance. Similarly, in the magnetized liner inertial fusion concept it is an open question as to how much surface non-uniformity correlates with the magneto-Rayleigh-Taylor instability, which develops during the implosion. This study presents experimental and simulation results, which demonstrate that the use of low current pulsed power devices in conjunction with appropriate diagnostics can be important for studying seeding mechanisms for the imminent generation of plasma instabilities in future research.

23. "A CAPTIVE ATLAS MISSILE EXPLODED DURING THE TEST ON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. "A CAPTIVE ATLAS MISSILE EXPLODED DURING THE TEST ON TEST STAND 1-A, 27 MARCH 1959, PUTTING THAT TEST STAND OUT-OF-COMMISSION. STAND WAS NOT REPAIRED FOR THE ATLAS PROGRAM BUT TRANSFERRED TO ROCKETDYNE AND MODIFIED FOR THE F-l ENGINE PROGRAM." - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

The Fermi Gamma-Ray Space Telescope, Exploding Stars, Neutron Stars, and Black Holes

NASA Technical Reports Server (NTRS)

Thompson, David J.

2010-01-01

Since August, 2008, the Fermi Gamma-ray Space Telescope has been scanning the sky, producing a full-sky image every three hours. These cosmic gamma-rays come from extreme astrophysical phenomena, many related to exploding stars (supernovae) or what these explosions leave behind: supernova remnants, neutron stars, and black holes. This talk uses sample Fermi results, plus simple demonstrations, to illustrate the exotic properties of these endpoints of stellar evolution.

[The exploding head syndrome].

PubMed

Bongers, K M; ter Bruggen, J P; Franke, C L

1991-04-06

The case is reported of a 47-year old female suffering from the exploding head syndrome. This syndrome consists of a sudden awakening due to a loud noise shortly after falling asleep, sometimes accompanied by a flash of light. The patient is anxious and experiences palpitations and excessive sweating. Most patients are more than fifty years of age. Further investigations do not reveal any abnormality. The pathogenesis is unknown, and no therapy other than reassurance is necessary.

Exploding head syndrome followed by sleep paralysis: a rare migraine aura.

PubMed

Evans, Randolph W

2006-04-01

A 26-year-old patient is described with a unique migraine aura. She described an 8-year history of episodes occurring 1 to 2 times yearly of exploding head syndrome followed by sleep paralysis followed by a migraine headache. She also had identical headaches without aura about once per week. Both aura symptoms, which may occur in the brainstem, resulted in activation of the trigeminovascular system through an unknown mechanism.

High fidelity studies of exploding foil initiator bridges, Part 3: ALEGRA MHD simulations

NASA Astrophysics Data System (ADS)

Neal, William; Garasi, Christopher

2017-01-01

Simulations of high voltage detonators, such as Exploding Bridgewire (EBW) and Exploding Foil Initiators (EFI), have historically been simple, often empirical, one-dimensional models capable of predicting parameters such as current, voltage, and in the case of EFIs, flyer velocity. Experimental methods have correspondingly generally been limited to the same parameters. With the advent of complex, first principles magnetohydrodynamic codes such as ALEGRA and ALE-MHD, it is now possible to simulate these components in three dimensions, and predict a much greater range of parameters than before. A significant improvement in experimental capability was therefore required to ensure these simulations could be adequately verified. In this third paper of a three part study, the experimental results presented in part 2 are compared against 3-dimensional MHD simulations. This improved experimental capability, along with advanced simulations, offer an opportunity to gain a greater understanding of the processes behind the functioning of EBW and EFI detonators.

High fidelity studies of exploding foil initiator bridges, Part 2: Experimental results

NASA Astrophysics Data System (ADS)

Neal, William; Bowden, Mike

2017-01-01

Simulations of high voltage detonators, such as Exploding Bridgewire (EBW) and Exploding Foil Initiators (EFI), have historically been simple, often empirical, one-dimensional models capable of predicting parameters such as current, voltage, and in the case of EFIs, flyer velocity. Experimental methods have correspondingly generally been limited to the same parameters. With the advent of complex, first principles magnetohydrodynamic codes such as ALEGRA MHD, it is now possible to simulate these components in three dimensions and predict greater range of parameters than before. A significant improvement in experimental capability was therefore required to ensure these simulations could be adequately verified. In this second paper of a three part study, data is presented from a flexible foil EFI header experiment. This study has shown that there is significant bridge expansion before time of peak voltage and that heating within the bridge material is spatially affected by the microstructure of the metal foil.

Review and perspectives of electrostatic turbulence and transport studies in the basic plasma physics device TORPEX

NASA Astrophysics Data System (ADS)

Avino, Fabio; Bovet, Alexandre; Fasoli, Ambrogio; Furno, Ivo; Gustafson, Kyle; Loizu, Joaquim; Ricci, Paolo; Theiler, Christian

2012-10-01

TORPEX is a basic plasma physics toroidal device located at the CRPP-EPFL in Lausanne. In TORPEX, a vertical magnetic field superposed on a toroidal field creates helicoidal field lines with both ends terminating on the torus vessel. We review recent advances in the understanding and control of electrostatic interchange turbulence, associated structures and their effect on suprathermal ions. These advances are obtained using high-resolution diagnostics of plasma parameters and wave fields throughout the whole device cross-section, fluid models and numerical simulations. Furthermore, we discuss future developments including the possibility of generating closed field line configurations with rotational transform using an internal toroidal wire carrying a current. This system will also allow the study of innovative fusion-relevant configurations, such as the snowflake divertor.

Laser ablation with applied magnetic field for electric propulsion

NASA Astrophysics Data System (ADS)

Batishcheva, Alla; Batishchev, Oleg; Cambier, Jean-Luc

2012-10-01

Using ultrafast lasers with tera-watt-level power allows efficient ablation and ionization of solid-density materials [1], creating dense and hot (˜100eV) plasma. We propose ablating small droplets in the magnetic nozzle configurations similar to mini-helicon plasma source [2]. Such approach may improve the momentum coupling compared to ablation of solid surfaces and facilitate plasma detachment. Results of 2D modeling of solid wire ablation in the applied magnetic field are presented and discussed. [4pt] [1] O. Batishchev et al, Ultrafast Laser Ablation for Space Propulsion, AIAA technical paper 2008-5294, -16p, 44th JPC, Hartford, 2008.[0pt] [2] O. Batishchev and J.L. Cambier, Experimental Study of the Mini-Helicon Thruster, Air Force Research Laboratory Report, AFRL-RZ-ED-TR-2009-0020, 2009.

Theoretical study of a consumable anode in a gas metal welding arc

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

Zhu, P.; Simpson, S.W.

1996-12-31

A better understanding of the behavior of the metal transfer process in a welding arc is important for further improvement of quality control for gas-metal-arc welding (GMAW). The problems related to the metal transfer are generally complicated because (a) the metal transfer process is strongly coupled with the arc plasma, which is not stable, for example, the length of the arc plasma varies during the formation and detachment of a metal droplet, and (b) the formation of the electrode droplet itself is influenced by energy transfer, the anode-plasma interface, and also the location of the liquid-solid interface inside the anode.more » This paper presents primary results of an investigation of the consumable anode in a gas metal welding arc. The study includes theoretical predictions of the properties related to metal transfer including moving anode temperature profile, welding arc length and arc current as a function of time for various wire feed rates, as well as numerical treatment of droplet formation. The anode temperature profile and the melting rate are analyzed by a metal transfer model which couples a two-dimensional arc model to a one-dimensional anode thermal model. The droplet formation is predicted by a quasi-one-dimensional dynamic model of a pendant drop which accounts for the electromagnet pinch effect, the surface tension, gravitation and the momentum transfer due to wire motion. Comparison between experimental observation and theoretical predictions will also be discussed.« less

Algebraic motion of vertically displacing plasmas

DOE PAGES

Pfefferle, D.; Bhattacharjee, A.

2018-02-27

In this paper, the vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to comemore » in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear “sinking” behaviour shown to be algebraic and decelerating. Finally, the acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.« less

Algebraic motion of vertically displacing plasmas

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

Pfefferle, D.; Bhattacharjee, A.

In this paper, the vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to comemore » in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear “sinking” behaviour shown to be algebraic and decelerating. Finally, the acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.« less

Preparation and characterization of copper-graphite composites by electrical explosion of wire in liquid.

PubMed

Bien, T N; Gul, W H; Bac, L H; Kim, J C

2014-11-01

Copper-graphite nanocomposites containing 5 vol.% graphite were prepared by a powder metallurgy route using an electrical wire explosion (EEW) in liquid method and spark plasma sintering (SPS) process. Graphite rods with a 0.3 mm diameter and copper wire with a 0.2 mm diameter were used as raw materials for EEWin liquid. To compare, a pure copper and copper-graphite mixture was also prepared. The fabricated graphite was in the form of a nanosheet, onto which copper particles were coated. Sintering was performed at 900 degrees C at a heating rate of 30 degrees C/min for 10 min and under a pressure of 70 MPa. The density of the sintered composite samples was measured by the Archimedes method. A wear test was performed by a ball-on-disc tribometer under dry conditions at room temperature in air. The presence of graphite effectively reduced the wear of composites. The copper-graphite nanocomposites prepared by EEW had lower wear rates than pure copper material and simple mixed copper-graphite.

Analysis of Precursor Properties of mixed Al/Alumel Cylindrical Wire Arrays*

NASA Astrophysics Data System (ADS)

Stafford, A.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Osborne, G. C.; Shlyaptseva, V. V.; Keim, S. F.; Coverdale, C. A.; Chuvatin, A. S.

2012-10-01

Previous studies of mid-Z (Cu and Ni) cylindrical wire arrays (CWAs) on Zebra have found precursors with high electron temperatures of >300 eV. However, past experiments with Al CWAs did not find the same high temperature precursors. New precursor experiments using mixed Al/Alumel (Ni 95%, Si 2%, and Al 2%) cylindrical wire arrays have been performed to understand how the properties of L-shell Ni precursor will change and whether Al precursor will be observed. Time gated spectra and pinholes are used to determine precursor plasma conditions for comparison with previous Alumel precursor experiments. A full diagnostic set which included more than ten different beam-lines was implemented. Future work in this direction is discussed. [4pt] *This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588, and in part by DE-FC52-06NA27586, and DE-FC52-06NA27616. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

Specific features of implosion of metallized fiber arrays

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

Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Aleksandrov, V. V.; Gritsuk, A. N.

2017-02-15

Implosion of metallized fiber arrays was studied experimentally at the Angara-5-1 facility. The use of such arrays makes it possible to investigate the production and implosion dynamics of plasmas of various metals (such as tin, indium, and bismuth) that were previously unavailable for such studies. The plasma production rates m-dot (in μg/(cm{sup 2} ns)) for different metals were determined and quantitatively compared. Varying the thickness of the metal layer deposited on kapron fibers (the total linear mass of the metal coating being maintained at the level of 220 μg/cm), the current and velocity of the plasma precursor were studied asmore » functions of the thickness of the metal coating. The strong difference in the rates of plasma production from the metal coating and kapron fibers results in the redistribution of the discharge current between the Z-pinch and the trailing fiber plasma. The outer boundary of the plasma produced from the metal coating is found to be stable against instabilities typical of the final stage of implosion of conventional wire arrays.« less

Different effects of acute and chronic immobilization stress on plasma testosterone levels in male Syrian hamsters.

PubMed

Tsuchiya, T; Horii, I

1995-01-01

Time-course variations in plasma testosterone levels after various periods of immobilization stress (10 min, 30 min, 2 h, 6 h) were examined in male Syrian hamsters. The immobilization stress consisted of placing the animals in a prone position and wrapping them with flexible steel wire gauze. This was done at room temperature. Testosterone levels were determined in blood samples taken after the hamsters were decapitated. Chronic (2 h, 6 h) immobilization stress produced a drastic and enduring fall in plasma testosterone levels. Reduction of plasma testosterone following the 6-h immobilization stress was observed even 18 h after the stress had been relieved. However, acute (10 min, 30 min) immobilization stress did not influence plasma testosterone. These findings indicated that the effect of immobilization stress on plasma testosterone in hamsters was not biphasic, which it is in rats. Further, these results suggest that immobilization stress in hamsters would be a valuable technique with which to investigate the effects of physiological ranges of testosterone on physiological and psychological functions.

Return Stroke Current Reflections in Rocket-Triggered Lightning

NASA Astrophysics Data System (ADS)

Caicedo, J.; Uman, M. A.; Jordan, D.; Biagi, C. J.; Hare, B.

2015-12-01

In the six years from 2009 to 2014, there have been eight triggered flashes at the ICLRT, from a total of 125, in which a total of ten return stroke channel-base currents exhibited a dip 3.0 to 16.6 μs after the initial current peak. Close range electric field measurements show a related dip following the initial electric field peak, and electric field derivative measurements show an associated bipolar pulse, confirming that this phenomenon is not an instrumentation effect in the current measurement. For six of the eight flashes, high-speed video frames show what appears to be suspended sections of unexploded triggering wire at heights of about 150 to 300 m that are illuminated when the upward current wave reaches them. The suspended wire can act as an impedance discontinuity, perhaps as it explodes, and cause a downward reflection of some portion of the upward-propagating current wave. This reflected wave travels down the channel and causes the dip in the measured channel-base current when it reaches ground and reflects upward. The modified transmission line model with exponential decay (MTLE) is used to model the close electric field and electric field derivatives of the postulated initial and reflected current waves, starting with the measured channel base current, and the results are compared favorably with measurements made at distances ranging from 92 to 444 m. From the measured time between current impulse initiation and the time the current reflection reaches the channel base and the current dip initiates, along with the reflection height from the video records, we find the average return stroke current speed for each of the ten strokes to be from 0.28 to 1.9×108 ms-1, with an error of ±0.01×108 ms-1 due to a ±0.1 μs uncertainty in the measurement. This represents the first direct measurement of return stroke current speed, all previous return stroke speed measurements being derived from the luminosity of the process.

Z-Pinch Fusion Propulsion

NASA Technical Reports Server (NTRS)

Miernik, Janie

2011-01-01

Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Shorter trips are better for humans in the harmful radiation environment of deep space. Nuclear propulsion and power plants can enable high Ispand payload mass fractions because they require less fuel mass. Fusion energy research has characterized the Z-Pinch dense plasma focus method. (1) Lightning is form of pinched plasma electrical discharge phenomena. (2) Wire array Z-Pinch experiments are commonly studied and nuclear power plant configurations have been proposed. (3) Used in the field of Nuclear Weapons Effects (NWE) testing in the defense industry, nuclear weapon x-rays are simulated through Z-Pinch phenomena.

Electromagnetic Extended Finite Elements for High-Fidelity Multimaterial Problems LDRD Final Report

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

Siefert, Christopher; Bochev, Pavel Blagoveston; Kramer, Richard Michael Jack

Surface effects are critical to the accurate simulation of electromagnetics (EM) as current tends to concentrate near material surfaces. Sandia EM applications, which include exploding bridge wires for detonator design, electromagnetic launch of flyer plates for material testing and gun design, lightning blast-through for weapon safety, electromagnetic armor, and magnetic flux compression generators, all require accurate resolution of surface effects. These applications operate in a large deformation regime, where body-fitted meshes are impractical and multimaterial elements are the only feasible option. State-of-the-art methods use various mixture models to approximate the multi-physics of these elements. The empirical nature of these modelsmore » can significantly compromise the accuracy of the simulation in this very important surface region. We propose to substantially improve the predictive capability of electromagnetic simulations by removing the need for empirical mixture models at material surfaces. We do this by developing an eXtended Finite Element Method (XFEM) and an associated Conformal Decomposition Finite Element Method (CDFEM) which satisfy the physically required compatibility conditions at material interfaces. We demonstrate the effectiveness of these methods for diffusion and diffusion-like problems on node, edge and face elements in 2D and 3D. We also present preliminary work on h -hierarchical elements and remap algorithms.« less

Spark gap device for precise switching

DOEpatents

Boettcher, G.E.

1984-10-02

A spark gap device for precise switching of an energy storage capacitor into an exploding bridge wire load is disclosed. Niobium electrodes having a melting point of 2,415 degrees centigrade are spaced apart by an insulating cylinder to define a spark gap. The electrodes are supported by conductive end caps which, together with the insulating cylinder, form a hermetically sealed chamber filled with an inert, ionizable gas, such as pure xenon. A quantity of solid radioactive carbon-14 within the chamber adjacent the spark gap serves as a radiation stabilizer. The sides of the electrodes and the inner wall of the insulating cylinder are spaced apart a sufficient distance to prevent unwanted breakdown initiation. A conductive sleeve may envelop the outside of the insulating member from the midpoint of the spark gap to the cap adjacent the cathode. The outer metallic surfaces of the device may be coated with a hydrogen-impermeable coating to lengthen the shelf life and operating life of the device. The device breaks down at about 1,700 volts for input voltage rates up to 570 volts/millisecond and allows peak discharge currents of up to 3,000 amperes from a 0.3 microfarad energy storage capacitor for more than 1,000 operations. 3 figs.

Development of circuit model for arcing on solar panels

NASA Astrophysics Data System (ADS)

Mehta, Bhoomi K.; Deshpande, S. P.; Mukherjee, S.; Gupta, S. B.; Ranjan, M.; Rane, R.; Vaghela, N.; Acharya, V.; Sudhakar, M.; Sankaran, M.; Suresh, E. P.

2010-02-01

The increased requirements of payload capacity of the satellites have resulted in much higher power requirements of the satellites. In order to minimize the energy loss during power transmission due to cable loss, use of high voltage solar panels becomes necessary. When a satellite encounters space plasma it floats negatively with respect to the surrounding space plasma environment. At high voltage, charging and discharging on solar panels causes the power system breakdown. Once a solar panel surface is charged and potential difference between surface insulator and conductor exceeds certain value, electrostatic discharge (ESD) may occur. This ESD may trigger a secondary arc that can destroy the solar panel circuit. ESD is also called as primary or minor arc and secondary is called major arc. The energy of minor arc is supplied by the charge stored in the coverglass of solar array and is a pulse of typically several 100 ns to several 100 μs duration. The damage caused by minor arc is less compared to major arcs, but it is observed that the minor arc is cause of major arc. Therefore it is important to develop an understanding of minor arc and mitigation techniques. In this paper we present a linear circuit analysis for minor arcs on solar panels. To study arcing event, a ground experimental facility to simulate space plasma environment has been developed at Facilitation Centre for Industrial Plasma Technologies (Institute for Plasma Research) in collaboration with Indian Space Research Organization's ISRO Satellite Technology Centre (ISAC). A linear circuit model has been developed to explain the experimental results by representing the coverglass, solar cell interconnect and wiring by an LCR circuit and the primary arc by an equivalent LR circuit. The aim of the circuit analysis is to predict the arc current which flows through the arc plasma. It is established from the model that the current depends on various parameters like potential difference between insulator and conductor, arc resistance, stored charge in the solar cell coverglass and the external capacitor that simulates wire harness. A close correlation between the experiments and circuit model results has been observed.

Algebraic motion of vertically displacing plasmas

NASA Astrophysics Data System (ADS)

Bhattacharjee, Amitava; Pfefferle, David; Hirvijoki, Eero

2017-10-01

The vertical displacement of tokamak plasmas is modelled during the non-linear phase by a free-moving current-carrying rod coupled to a set of fixed conducting wires and a cylindrical conducting shell. The models capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the vacuum vessel. The plasma is assumed not to vary during the VDE such that it behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented from coming in contact with the wall due to steep effective potential barriers by the eddy currents, and will hence oscillate at Alfvénic frequencies about a given force-free position. In addition to damping oscillations, resistivity allows for the column to drift towards the vessel on slow flux penetration timescales. The initial exponential motion of the plasma, i.e. the resistive vertical instability, is succeeded by a non-linear sinking behaviour, that is shown analytically to be algebraic and decelerative. The acceleration of the plasma column often observed in experiments is thus conjectured to originate from an early sharing of toroidal current between the core, the halo plasma and the wall or from the thermal quench dynamics precipitating loss of plasma current

High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility.

PubMed

Koch, J A; Stewart, R E; Beiersdorfer, P; Shepherd, R; Schneider, M B; Miles, A R; Scott, H A; Smalyuk, V A; Hsing, W W

2012-10-01

Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-α at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

Neutrino Emission from Supernovae

NASA Astrophysics Data System (ADS)

Janka, Hans-Thomas

Supernovae are the most powerful cosmic sources of MeV neutrinos. These elementary particles play a crucial role when the evolution of a massive star is terminated by the collapse of its core to a neutron star or a black hole and the star explodes as supernova. The release of electron neutrinos, which are abundantly produced by electron captures, accelerates the catastrophic infall and causes a gradual neutronization of the stellar plasma by converting protons to neutrons as dominant constituents of neutron star matter. The emission of neutrinos and antineutrinos of all flavors carries away the gravitational binding energy of the compact remnant and drives its evolution from the hot initial to the cold final state. The absorption of electron neutrinos and antineutrinos in the surroundings of the newly formed neutron star can power the supernova explosion and determines the conditions in the innermost supernova ejecta, making them an interesting site for the nucleosynthesis of iron-group elements and trans-iron nuclei.

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

Zestos, Alexander G.; Yang, Cheng; Jacobs, Christopher B.

Carbon nanomaterials are advantageous as electrodes for neurotransmitter detection, but the difficulty of nanomaterials deposition on electrode substrates limits the reproducibility and future applications. In our study, we used plasma enhanced chemical vapor deposition (PECVD) to directly grow a thin layer of carbon nanospikes (CNS) on cylindrical metal substrates. No catalyst is required and the CNS surface coverage is uniform over the cylindrical metal substrate. We characterized the CNS growth on several metallic substrates including tantalum, niobium, palladium, and nickel wires. Using fast-scan cyclic voltammetry (FSCV), bare metal wires could not detect 1 mu M dopamine while carbon nanospike coatedmore » wires could. Moreover, the highest sensitivity and optimized S/N ratio was recorded from carbon nanospike-tantalum (CNS-Ta) microwires grown for 7.5 minutes, which had a LOD of 8 +/- 2 nM for dopamine with FSCV. CNS-Ta microelectrodes were more reversible and had a smaller Delta E-p for dopamine than carbon-fiber microelectrodes, suggesting faster electron transfer kinetics. The kinetics of dopamine redox were adsorption controlled at CNS-Ta microelectrodes and repeated electrochemical measurements displayed stability for up to ten hours in vitro and over a ten day period as well. The oxidation potential was significantly different for ascorbic acid and uric acid compared to dopamine. Finally, growing carbon nanospikes on metal wires is a promising method to produce uniformly-coated, carbon nanostructured cylindrical microelectrodes for sensitive dopamine detection.« less

Advanced X-ray Imaging Crystal Spectrometer for Magnetic Fusion Tokamak Devices

NASA Astrophysics Data System (ADS)

Lee, S. G.; Bak, J. G.; Bog, M. G.; Nam, U. W.; Moon, M. K.; Cheon, J. K.

2008-03-01

An advanced X-ray imaging crystal spectrometer is currently under development using a segmented position sensitive detector and time-to-digital converter (TDC) based delay-line readout electronics for burning plasma diagnostics. The proposed advanced XICS utilizes an eight-segmented position sensitive multi-wire proportional counter and supporting electronics to increase the spectrometer performance includes the photon count-rate capability and spatial resolution.

The formation of reverse shocks in magnetized high energy density supersonic plasma flows

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

Lebedev, S. V., E-mail: s.lebedev@imperial.ac.uk, E-mail: l.suttle10@imperial.ac.uk; Suttle, L.; Swadling, G. F.

A new experimental platform was developed, based on the use of supersonic plasma flow from the ablation stage of an inverse wire array z-pinch, for studies of shocks in magnetized high energy density physics plasmas in a well-defined and diagnosable 1-D interaction geometry. The mechanism of flow generation ensures that the plasma flow (Re{sub M} ∼ 50, M{sub S} ∼ 5, M{sub A} ∼ 8, V{sub flow} ≈ 100 km/s) has a frozen-in magnetic field at a level sufficient to affect shocks formed by its interaction with obstacles. It is found that in addition to the expected accumulation of stagnated plasma in a thin layer at the surface ofmore » a planar obstacle, the presence of the magnetic field leads to the formation of an additional detached density jump in the upstream plasma, at a distance of ∼c/ω{sub pi} from the obstacle. Analysis of the data obtained with Thomson scattering, interferometry, and local magnetic probes suggests that the sub-shock develops due to the pile-up of the magnetic flux advected by the plasma flow.« less

Observation of 23 supernovae that exploded <300 pc from Earth during the past 300 kyr

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

Firestone, R. B., E-mail: rbfirestone@lbl.gov

2014-07-01

Four supernovae (SNe), exploding ≤300 pc from Earth, were recorded 44, 37, 32, and 22 kyr ago in the radiocarbon ({sup 14}C) record during the past 50 kyr. Each SN left a nearly identical signature in the record, beginning with an initial sudden increase in atmospheric radiocarbon, when the SN exploded, followed by a hiatus of 1500 yr, and concluding with a sustained 2000 yr increase in global radiocarbon due to γ-rays produced by diffusive shock in the SN remnant (SNR). For the past 18 kyr excess radiocarbon has decayed with the {sup 14}C half-life. SN22kyrBP, is identified as themore » Vela SN that exploded 250 ± 30 pc from Earth. These SN are confirmed in the {sup 10}Be, {sup 26}Al, {sup 36}Cl, and NO{sub 3}{sup −} geologic records. The rate of near-Earth SNe is consistent with the observed rate of historical SNe giving a galactic rate of 14 ± 3 kyr{sup –1} assuming the Chandra Galactic Catalog SNR distribution. The Earth has been used as a calorimeter to determine that ≈2 × 10{sup 49} erg were released as γ-rays at the time of each SN explosion and ≈10{sup 50} erg in γ-rays following each SN. The background rate of {sup 14}C production by cosmic rays has been determined as 1.61 atoms cm{sup –2} s{sup –1}. Approximately 1/3 of the cosmic ray energy produced by diffusive shock in the SNR was observed to be emitted as high-energy γ-rays. Analysis of the {sup 10}Be/{sup 9}Be ratio in marine sediment identified 19 additional near-Earth SNe that exploded 50-300 kyr ago. Comparison of the radiocarbon record with global temperature variations indicated that each SN explosion is correlated with a concurrent global warming of ≈3°C-4°C.« less

Ductile-Phase-Toughened Tungsten for Plasma-Facing Materials

NASA Astrophysics Data System (ADS)

Cunningham, Kevin Hawkins

A variety of processing approaches were employed to fabricate ductile-phase-toughened (DPT) tungsten (W) composites. Mechanical testing and analytical modeling were used to guide composite development. This work provides a basis for further development of W composites to be used in structural divertor components of future fusion reactors. W wire was tested in tension, showing significant ductility and strength. Coatings of copper (Cu) or tungsten carbide (WC) were applied to the W wire via electrodeposition and carburization, respectively. Composites were fabricated using spark plasma sintering (SPS) to consolidate W powders together with each type of coated W wire. DPT behavior, e.g. crack arrest and crack bridging, was not observed in three-point bend testing of the sintered composites. A laminate was fabricated by hot pressing W and Cu foils together with W wires, and subsequently tested in tension. This laminate was bonded via hot pressing to thick W plate as a reinforcing layer, and the composite was tested in three-point bending. Crack arrest was observed along with some fiber pullout, but significant transverse cracking in the W plate confounded further fracture toughness analysis. The fracture toughness of thin W plate was measured in three-point bending. W plates were brazed with Cu foils to form a laminate. Crack arrest and crack bridging were observed in three-point bend tests of the laminate, and fracture resistance curves were successfully calculated for this DPT composite. An analytical model of crack bridging was developed using the basis described by Chao in previous work by the group. The model uses the specimen geometry, matrix properties, and the stress-displacement function of a ductile reinforcement ("bridging law") to calculate the fracture resistance curve (R-curve) and load-displacement curve (P-D curve) for any test specimen geometry. The code was also implemented to estimate the bridging law of an arbitrary composite using R-curve data. Finally, a parametric study was performed to quantitatively determine the necessary mechanical properties of useful toughening reinforcements for a DPT W composite. The analytical model has a broad applicability for any DPT material.

A Guide to Lexical Acquisition in the JANUS System.

DTIC Science & Technology

1986-02-01

compounds and not verbs with case prepositions: Don’t tread on the banana peel It*- been trodden on already Go ahead, stare at me I like to be stared...agent is italicized. MIDDLE EFFECTIVE The bananas ripened The ,un ripened the bananas The bomb exploded The police exploded the bomb Mary believed the...verb is carried out. Bob rhythmically chopped the celery Christian peeled the tomatoes skillfully Slowly, Nancy melted the butter in the pan 4.2.4.4

Torpedoes and Their Impact on Naval Warfare

DTIC Science & Technology

2017-01-01

wind to get to their destinations. This meant ships were no Overview 11 longer at the mercy of nature since they were no longer dependent on wind and...ships had to slip their cables to avoid the exploding torpedoes. However, although 10 mines exploded, none of them came in contact with a French...ahead” just doesn’t have the same ring to it; this appears to be a case where it is better to be eloquent rather than technically accurate. The

Dynamic Detection of Malicious Code in COTS Software

DTIC Science & Technology

2000-04-01

run the following documented hostile applets or ActiveX of these tools work only on mobile code (Java, ActiveX , controls: 16-11 Hostile Applets Tiny...Killer App Exploder Runner ActiveX Check Spy eSafe Protect Desktop 9/9 blocked NB B NB 13/17 blocked NB Surfinshield Online 9/9 blocked NB B B 13/17...Exploder is an ActiveX control top (@). that performs a clean shutdown of your computer. The interface is attractive, although rather complex, as McLain’s

Control of dispersed-phase temperature in plasma flows by the spectral-brightness pyrometry method

NASA Astrophysics Data System (ADS)

Dolmatov, A. V.; Gulyaev, I. P.; Gulyaev, P. Yu; Iordan, V. I.

2016-02-01

In the present work, we propose a new method for measuring the distribution of temperature in the ensembles of condensed-phase particles in plasma spray flows. Interrelation between the spectral temperature of the particles and the distribution of camera brightness signal is revealed. The established inter-relation enables an in-situ calibration of measuring instruments using the objects under study. The spectral-brightness pyrometry method was approbated on a Plazer plasma-arc wire spraying facility at the Paton Institute of Electrical Welding (Ukrainian Academy of Sciences, Kiev) and on the Thermoplasma 50-1 powder spraying facility at the Institute of Theoretical and Applied Mechanics (Russian Academy of Sciences, Siberian Branch, Novosibirsk). The work was supported by the Russian Foundation for Basic Research (Grants Nos. 14-08-90428 and 15-48-00100).

Electro-mechanical probe positioning system for large volume plasma device

NASA Astrophysics Data System (ADS)

Sanyasi, A. K.; Sugandhi, R.; Srivastava, P. K.; Srivastav, Prabhakar; Awasthi, L. M.

2018-05-01

An automated electro-mechanical system for the positioning of plasma diagnostics has been designed and implemented in a Large Volume Plasma Device (LVPD). The system consists of 12 electro-mechanical assemblies, which are orchestrated using the Modbus communication protocol on 4-wire RS485 communications to meet the experimental requirements. Each assembly has a lead screw-based mechanical structure, Wilson feed-through-based vacuum interface, bipolar stepper motor, micro-controller-based stepper drive, and optical encoder for online positioning correction of probes. The novelty of the system lies in the orchestration of multiple drives on a single interface, fabrication and installation of the system for a large experimental device like the LVPD, in-house developed software, and adopted architectural practices. The paper discusses the design, description of hardware and software interfaces, and performance results in LVPD.

Spectra of laser generated relativistic electrons using cone-wire targets

NASA Astrophysics Data System (ADS)

Sawada, Hiroshi

2012-10-01

We report on the characterization of the in situ energy spectrum of fast electrons generated by ultra-intense (I˜10^19 W cm-2) short pulse (τ˜0.7 and 10 ps) laser-plasma interactions using the TITAN and OMEGA EP lasers. That in situ spectrum is a key component of ignition efficiency for the Fast Ignition (FI) Inertial Confinement Fusion (ICF) concept. It is challenging to model and, until now, has resisted direct experimental characterization; other techniques have very large error bars or measure the modified spectrum of escaped electrons. This technique also gives an indication of the forward coupling efficiency of the laser to fast electrons. This information is derived from the measurement of Cu Kα x-rays emitted from a 1.5 mm long Cu wire attached to the tip of Au or Al cone targets. Fast electrons, generated in the cone, transport through the cone tip with a fraction of coupling to the wire. Electrons in the wire excite fluorescence measured by a monochromatic imager and an absolutely calibrated HOPG spectrometer. An implicit hybrid-PIC code, LSP, is applied to deduce electron parameters from the Kα measurements. Experiments on the TITAN laser with Au cones attached to wires show an increase in pre-pulse energy from 17 to 1000 mJ, decreases the fast electron fraction entering the wire from 8.4% to 2.5%. On OMEGA EP with Al cones attached to wires, total Kα yield, normalized to laser energy, drops ˜30% for laser pulse length increasing from 1 to 10 ps, indicative of a saturation mechanism. For Au cones, Kα yields were 50% of that measured for Al cones indicating a strong material dependence. In all cases, the spatial distribution can only be fit with a two-temperature electron energy distribution, the relative fractions depending on prepulse level. These results are being used to develop an optimum cone design for integrated FI experiments. This work was performed under the auspices of the USDOE by LLNL under Contract DE-AC52-07NA27344 and DE-FG-02-05ER54834.

Effect of steam explosion and microbial fermentation on cellulose and lignin degradation of corn stover.

PubMed

Chang, Juan; Cheng, Wei; Yin, Qingqiang; Zuo, Ruiyu; Song, Andong; Zheng, Qiuhong; Wang, Ping; Wang, Xiao; Liu, Junxi

2012-01-01

In order to increase nutrient values of corn stover, effects of steam explosion (2.5 MPa, 200 s) and Aspergillus oryzae (A. oryzae) fermentation on cellulose and lignin degradation were studied. The results showed the contents of cellulose, hemicellulose and lignin in the exploded corn stover were 8.47%, 50.45% and 36.65% lower than that in the untreated one, respectively (P<0.05). The contents of cellulose and hemicellulose in the exploded and fermented corn stover (EFCS) were decreased by 24.36% and 69.90%, compared with the untreated one (P<0.05); decreased by 17.35% and 38.59%, compared with the exploded one (P<0.05). The scanning electron microscope observations demonstrated that the combined steam explosion and fermentation destructed corn stover. The activities of enzymes in EFCS were increased. The metabolic experiment showed that about 8% EFCS could be used to replace corn meal in broiler diets, which made EFCS become animal feedstuff possible. Copyright © 2011 Elsevier Ltd. All rights reserved.

High fidelity studies of exploding foil initiator bridges, Part 1: Experimental method

NASA Astrophysics Data System (ADS)

Bowden, Mike; Neal, William

2017-01-01

Simulations of high voltage detonators, such as Exploding Bridgewire (EBW) and Exploding Foil Initiators (EFI), have historically been simple, often empirical, one-dimensional models capable of predicting parameters such as current, voltage and in the case of EFIs, flyer velocity. Correspondingly, experimental methods have in general been limited to the same parameters. With the advent of complex, first principles magnetohydrodynamic codes such as ALEGRA and ALE-MHD, it is now possible to simulate these components in three dimensions, predicting a much greater range of parameters than before. A significant improvement in experimental capability was therefore required to ensure these simulations could be adequately validated. In this first paper of a three part study, the experimental method for determining the current, voltage, flyer velocity and multi-dimensional profile of detonator components is presented. This improved capability, along with high fidelity simulations, offer an opportunity to gain a greater understanding of the processes behind the functioning of EBW and EFI detonators.

Understanding the Electrical Interplay Between a Firing Set and Exploding Metal

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

O'Malley, Patrick D.; Garasi, Christopher J.

There is a significant body of work going back centuries that describes in detail the workings of metals that are rapidly transitioned from a solid to a vapor and beyond. These are known as exploding metals and have a variety of applications. A common way to cause metals to explode is through the use of a capacitive discharge circuit (CDC). In the past, methods have been used to simplify the complex, non-linear interaction between the CDC and the metal but in the process some important physics has been lost. This report provides insight into the complex interplay of the metalmore » and the various elements of the CDC. In explaining the basic phenomena in greater detail than has been done before, other interesting cases such as "dwell" are understood in a new light. The net result is a detailed look at the mechanisms which shape the current pulses that scientists and engineers have observed for many decades.« less

Did René Descartes Have Exploding Head Syndrome?

PubMed

Otaiku, Abidemi Idowu

2018-04-15

René Descartes (1596-1650), "the Father of Modern Philosophy" and advocate of mind-body dualism, had three successive dreams on November 10, 1619 that changed the trajectory of his life and the trajectory of human thought. Descartes' influential dreams have been of interest to a number of commentators including the famous neurologist and psychoanalyst Sigmund Freud. Descartes' second dream in particular, in which he heard a loud noise in his head before seeing a bright flash of light upon awakening, has been discussed extensively. Commentators have employed psychoanalytic and medical explanations to account for Descartes' unusual nocturnal experience. In this tradition, I propose that Descartes' second dream was not a dream at all; rather, it was an episode of exploding head syndrome; a benign and relatively common parasomnia. I further suggest that Adrien Baillet's account of Descartes' experience constitutes the earliest description of exploding head syndrome, predating the account described by Silas Weir Mitchell in 1876 by nearly 200 years. © 2018 American Academy of Sleep Medicine.

Variable polarity plasma arc welding on the Space Shuttle external tank

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Bayless, E. O., Jr.; Jones, C. S., III; Munafo, P. M.; Biddle, A. P.; Wilson, W. A.

1984-01-01

Variable polarity plasma arc (VPPA) techniques used at NASA's Marshall Space Flight Center for the fabrication of the Space Shuttle External Tank are presentedd. The high plasma arc jet velocities of 300-2000 m/s are produced by heating the plasma gas as it passes through a constraining orifice, with the plasma arc torch becoming a miniature jet engine. As compared to the GTA jet, the VPPA has the following advantages: (1) less sensitive to contamination, (2) a more symmetrical fusion zone, and (3) greater joint penetration. The VPPA welding system is computerized, operating with a microprocessor, to set welding variables in accordance with set points inputs, including the manipulator and wire feeder, as well as torch control and power supply. Some other VPPA welding technique advantages are: reduction in weld repair costs by elimination of porosity; reduction of joint preparation costs through elimination of the need to scrape or file faying surfaces; reduction in depeaking costs; eventual reduction of the 100 percent-X-ray inspection requirements. The paper includes a series of schematic and block diagrams.

Electron density measurements from the shot noise collected on the STEREO/WAVES antennas

NASA Astrophysics Data System (ADS)

Zouganelis, Ioannis; Bale, Stuart; Bougeret, J.-L.; Maksimovic, Milan

One of the most reliable techniques for in situ measuring the electron density and temperature in space plasmas is the quasi-thermal noise spectroscopy. When a passive electric antenna is immersed in a stable plasma, the thermal motion of the ambient particles produces electrostatic fluctuations, which can be adequately measured with a sensitive wave receiver connected to a wire dipole antenna. Unfortunately, on STEREO, the S/WAVES design does not let us use this high accuracy technique because the antennas have a large surface area and the resulting shot noise spectrum in the solar wind dominates the power at lower frequencies. We can use, instead, the electron shot noise to infer the plasma density. For this, we use well calibrated Wind particle data to deduce the base capacitance of the S/WAVES instrument in a special configuration when the STEREO-B spacecraft was just downstream of Wind. The electron plasma density deduced is then compared to the S/PLASTIC ion density and its accuracy is estimated of up to 10

Feasibility of Underwater Friction Stir Welding of Hardenable Alloy Steel

DTIC Science & Technology

2010-12-01

Base Material CNC – Computer Numerical Controlled EDM – Electrical Discharge Machining FSP – Friction Stir Processing FSW – Friction Stir Welding...Hydrogen content was determined through vacuum hot extraction according to ASTM E 146-83. All other components were analyzed by direct current plasma ...emission spectroscopy according to ASTM E 1097-07. C. MICROSTRUCTURE ANALYSIS 1. Specimen Preparation A Charmilles Andrew EF630 CNC Wire EDM

Progress in Fast Ignition Studies with Electrons and Protons

NASA Astrophysics Data System (ADS)

MacKinnon, A. J.; Akli, K. U.; Bartal, T.; Beg, F. N.; Chawla, S.; Chen, C. D.; Chen, H.; Chen, S.; Chowdhury, E.; Fedosejevs, R.; Freeman, R. R.; Hey, D.; Higginson, D.; Key, M. H.; King, J. A.; Link, A.; Ma, T.; MacPhee, A. G.; Offermann, D.; Ovchinnikov, V.; Pasley, J.; Patel, P. K.; Ping, Y.; Schumacher, D. W.; Stephens, R. B.; Tsui, Y. Y.; Wei, M. S.; Van Woerkom, L. D.

2009-09-01

Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) concept for initiating burn in a fusion capsule. In order to investigate critical aspects needed for a FI point design, experiments were performed to study 1) laser-to-electrons or protons conversion issues and 2) laser-cone interactions including prepulse effects. A large suite of diagnostics was utilized to study these important parameters. Using cone—wire surrogate targets it is found that pre-pulse levels on medium scale lasers such as Titan at Lawrence Livermore National Laboratory produce long scale length plasmas that strongly effect coupling of the laser to FI relevant electrons inside cones. The cone wall thickness also affects coupling to the wire. Conversion efficiency to protons has also been measured and modeled as a function of target thickness, material. Conclusions from the proton and electron source experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed. In conclusion, a program of study will be presented based on understanding the fundamental physics of the electron or proton source relevant to FI.

Comparison of Two Wire Model With Low MN Map

NASA Astrophysics Data System (ADS)

Punjabi, Alkesh; Ali, Halima; Boozer, Allen

2003-10-01

Among the perturbations that affect the width of the stochastic layer of a single-null divertor tokamak is naturally occurring perturbations with low toroidal and poloidal mode numbers. In present day tokamaks, the n= +/- 1, m=1 Fourier component of the field error is roughly estimated to be typically of the order 10-3 times the toroidal field /1/. In this work, we analyze the features of the stochastic layer and the footprint of field lines using the Low MN Map (LMN)/2,3/. We also perform similar analysis using Rieman Two Wire Model (TWM) /1/. We then compare the results of the two approaches when the parameters of the TWM and of LMN are both 10-3. We show that the footprints from the TWM and the LMN match quantitatively and qualitatively. We compare the safety factor, Liapunov exponents, semi-connection length, and strike angles as functions of starting position of field lines in stochastic layer from the TWM and the LMN. We also discuss and compare the accuracy and the speed of both approaches. This work is done under the DOE grant number DE-FG02-01ER54624. 1. A. Reiman, Phys. Plasmas 3, 906 (1996). 2. A. Punjabi et al, Phys. Rev. lett., 69, 3322 (1992). 3. A. Punjabi et al, Phys. Plasmas, 4, 337 (1997).

Review of Slow-Wave Structures

NASA Technical Reports Server (NTRS)

Wallett, Thomas M.; Qureshi, A. Haq

1994-01-01

The majority of recent theoretical and experimental reports published in the literature dealing with helical slow-wave structures focus on the dispersion characteristics and their effects due to the finite helix wire thickness and attenuation, dielectric loading, metal loading, and the introduction of plasma. In many papers, an effective dielectric constant is used to take into account helix wire dimensions and conductivity losses, while the propagation constant of the signal and the interaction impedance of the structure are found to depend on the surface resistivity of the helix. Also, various dielectric supporting rods are simulated by one or several uniform cylinders having an effective dielectric constant, while metal vane loading and plasma effects are incorporated in the effective dielectric constant. The papers dealing with coupled cavities and folded or loaded wave guides describe equivalent circuit models, efficiency enhancement, and the prediction of instabilities for these structures. Equivalent circuit models of various structures are found using computer software programs SUPERFISH and TOUCHSTONE. Efficiency enhancement in tubes is achieved through dynamic velocity and phase adjusted tapers using computer techniques. The stability threshold of unwanted antisymmetric and higher order modes is predicted using SOS and MAGIC codes and the dependence of higher order modes on beam conductance, section length, and effective Q of a cavity is shown.

The effects of nanomaterials on blood coagulation in hemostasis and thrombosis.

PubMed

Simak, Jan; De Paoli, Silvia

2017-09-01

The blood coagulation balance in the organism is achieved by the interaction of the blood platelets (PLTs) with the plasma coagulation system (PCS) and the vascular endothelial cells. In healthy organism, these systems prevent thrombosis and, in events of vascular damage, enable blood clotting to stop bleeding. The dysregulation of hemostasis may cause serious thrombotic and/or hemorrhagic pathologies. Numerous engineered nanomaterials are being investigated for biomedical purposes and are unavoidably exposed to the blood. Also, nanomaterials may access vascular system after occupational, environmental, or other types of exposure. Thus, it is essential to evaluate the effects of engineered nanomaterials on hemostasis. This review focuses on investigations of nanomaterial interactions with the blood components involved in blood coagulation: the PCS and PLTs. Particular emphases include the pathophysiology of effects of nanomaterials on the PCS, including the kallikrein-kinin system, and on PLTs. Methods for investigating these interactions are briefly described, and a review of the most important studies on the interactions of nanomaterials with plasma coagulation and platelets is provided. WIREs Nanomed Nanobiotechnol 2017, 9:e1448. doi: 10.1002/wnan.1448 For further resources related to this article, please visit the WIREs website. © Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

The PIX-2 experiment: An overview

NASA Astrophysics Data System (ADS)

Purvis, C. K.

1985-03-01

The second Plasma Interactions Experiment (PIX-2) was launched in January 1983 as a piggyback on the second stage of the Delta launch vehicle that carried IRAS into orbit. Placed in a 870 km circular polar orbit, it returned 18 hrs of data on the plasma current collection and arcing behavior of solar arrays biased to +/-1000 V in steps. The four 500 sq cm solar array segments were biased singly and in combinations. In addition to the array segments PIX-2 carried a Sun sensor, a Langmuir probe to measure electron currents, and a hot-wire filament electron emitter to control vehicle potential during positive array bias sequences. The PIX-2 experiment is reviewed from program and operational perspectives.

Gallium assisted plasma enhanced chemical vapor deposition of silicon nanowires.

PubMed

Zardo, I; Yu, L; Conesa-Boj, S; Estradé, S; Alet, Pierre Jean; Rössler, J; Frimmer, M; Roca I Cabarrocas, P; Peiró, F; Arbiol, J; Morante, J R; Fontcuberta I Morral, A

2009-04-15

Silicon nanowires have been grown with gallium as catalyst by plasma enhanced chemical vapor deposition. The morphology and crystalline structure has been studied by electron microscopy and Raman spectroscopy as a function of growth temperature and catalyst thickness. We observe that the crystalline quality of the wires increases with the temperature at which they have been synthesized. The crystalline growth direction has been found to vary between <111> and <112>, depending on both the growth temperature and catalyst thickness. Gallium has been found at the end of the nanowires, as expected from the vapor-liquid-solid growth mechanism. These results represent good progress towards finding alternative catalysts to gold for the synthesis of nanowires.

Imaging bolometer

DOEpatents

Wurden, G.A.

1999-01-19

Radiation-hard, steady-state imaging bolometer is disclosed. A bolometer employing infrared (IR) imaging of a segmented-matrix absorber of plasma radiation in a cooled-pinhole camera geometry is described. The bolometer design parameters are determined by modeling the temperature of the foils from which the absorbing matrix is fabricated by using a two-dimensional time-dependent solution of the heat conduction equation. The resulting design will give a steady-state bolometry capability, with approximately 100 Hz time resolution, while simultaneously providing hundreds of channels of spatial information. No wiring harnesses will be required, as the temperature-rise data will be measured via an IR camera. The resulting spatial data may be used to tomographically investigate the profile of plasmas. 2 figs.

Imaging bolometer

DOEpatents

Wurden, Glen A.

1999-01-01

Radiation-hard, steady-state imaging bolometer. A bolometer employing infrared (IR) imaging of a segmented-matrix absorber of plasma radiation in a cooled-pinhole camera geometry is described. The bolometer design parameters are determined by modeling the temperature of the foils from which the absorbing matrix is fabricated by using a two-dimensional time-dependent solution of the heat conduction equation. The resulting design will give a steady-state bolometry capability, with approximately 100 Hz time resolution, while simultaneously providing hundreds of channels of spatial information. No wiring harnesses will be required, as the temperature-rise data will be measured via an IR camera. The resulting spatial data may be used to tomographically investigate the profile of plasmas.

Decontamination of chemical and biological warfare (CBW) agents using an atmospheric pressure plasma jet (APPJ)

NASA Astrophysics Data System (ADS)

Herrmann, H. W.; Henins, I.; Park, J.; Selwyn, G. S.

1999-05-01

The atmospheric pressure plasma jet (APPJ) [A. Schütze et al., IEEE Trans. Plasma Sci. 26, 1685 (1998)] is a nonthermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O), which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered at 13.56 MHz rf. While passing through the plasma, the feedgas becomes excited, dissociated or ionized by electron impact. Once the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, but the fast-flowing effluent still contains neutral metastable species (e.g., O2*, He*) and radicals (e.g., O, OH). This reactive effluent has been shown to be an effective neutralizer of surrogates for anthrax spores and mustard blister agent. Unlike conventional wet decontamination methods, the plasma effluent does not cause corrosion and it does not destroy wiring, electronics, or most plastics, making it highly suitable for decontamination of sensitive equipment and interior spaces. Furthermore, the reactive species in the effluent rapidly degrade into harmless products leaving no lingering residue or harmful by-products.

Shuttle Orbiter tethered subsatellite for exploring and tapping space plasmas

NASA Technical Reports Server (NTRS)

Banks, P. M.; Williamson, P. R.; Oyama, K. I.

1981-01-01

Consideration is given to the possibilities for studies in space plasma physics offered by a subsatellite mechanically tethered above the Space Shuttle Orbiter by a long conducting wire. The proposed experiment, designated the Shuttle Electrodynamic Tether Systems (SETS) is based on the concept of collecting electrons at the subsatellite and ejecting them from the Orbiter, made possible by the emf generated by the motion of the tether across geomagnetic field lines. The power generated in this manner can be used both for practical purposes within the Orbiter and for the creation of large-amplitude plasma and electromagnetic waves within the surrounding plasma. For a conducting spherical subsatellite 30 m in diameter with a 10-km tether drawing 1 A, calculations show that emfs on the order of 1000-2000 V and energy dissipation of as much as 10,000 W can be obtained, accompanied by the generation of two regions of net electric charge in the ionosphere. Scientific studies considered for SETS include the measurement of MHD waves artificially generated in the ionosphere, the investigation of current-driven plasma instabilities, VLF wave generation and the simulation of electrodynamics associated with the motion of celestial bodies through plasma.

Design of a mission network system using SpaceWire for scientific payloads onboard the Arase spacecraft

NASA Astrophysics Data System (ADS)

Takashima, Takeshi; Ogawa, Emiko; Asamura, Kazushi; Hikishima, Mitsuru

2018-05-01

Arase is a small scientific satellite program conducted by the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, which is dedicated to the detailed study of the radiation belts around Earth through in situ observations. In particular, the goal is to directly observe the interaction between plasma waves and particles, which cause the generation of high-energy electrons. To observe the waves and particles in detail, we must record large volumes of burst data with high transmission rates through onboard mission network systems. For this purpose, we developed a high-speed and highly reliable mission network based on SpaceWire, as well as a new and large memory data recorder equipped with a data search function based on observation time (the time index, TI, is the satellite time starting from when the spacecraft is powered on.) with respect to the orbital data generated in large quantities. By adopting a new transaction concept of a ring topology network with SpaceWire, we could secure a redundant mission network system without using large routers and having to suppress the increase in cable weight. We confirmed that their orbit performs as designed.[Figure not available: see fulltext.

On performance of cylindrical dipole antenna in diagnostics of wave phenomena in space plasma

NASA Astrophysics Data System (ADS)

Kiraga, A.

Tubular and wire antennas have been employed since an advent of in situ measurements in space. It is generally accepted that they are well suited to recipe electromagnetic radiation from remote sources as well as divers local plasma emissions. Quasi thermal noise spectroscopy provides an example of well documented, both experimentally and theoretically, technique to study solar wind plasma. In many data sets of wave spectra, recorded with use of tubular or wire antennas at all altitudes inside a plasma sphere, there is pronounced, permanent, variable frequency spectral structure, routinely assigned to upper hybrid band (UHR) emissions. On the other hand, spectral structure, which could be assigned to upper hybrid band, is less pronounced and infrequent, in sets of wave spectra recorded in polar region with the use of spherical double probes. These apparently inconsistent observations have not drawn much attention of wave community. Assignment to UHR emission have been bolstered by theoretical plausibility, permanency in data sets, frequency verification with independent techniques and conviction that measurements were performed with good voltmeter with well known properties. It has been recognized that stray capacitance acts as a voltage divider and underestimates real voltage imposed on antenna. But in sufficiently dense and cold main plasma component, even short antenna is inductive in some frequency band below upper hybrid frequency. Stray capacitance and antenna inductance result in circuit resonance, which is very pronounced, if antenna resistance is low and input resistance is high. In such circumstances, a good voltmeter concept is very misleading. In this report we show that good voltmeter concept is not sufficient for interpretation of passive mode spectra recorded with tubular antenna on IK -19, APEX and CORONAS satellites. With orbit inclination of ~80deg and altitude range of 500-3000km, very divers plasmas were encountered, but distinct plasma emission within upper hybrid band do not show up. In equivalent circuit simulations, salient spectral characteristics can be matched and related to specific impedances. Equivalent circuit analysis was enforced by apparent difference between local plasma frequencies derived from onboard topside sounder data and frequencies of adjacent maximum in passive mode spectra. It has been subsequently verified and developed with the aid of impedance measurements, onboard sounder data and analysis of electron beam induced spectra. We show that circuit resonance can be neatly controlled to provide very low interference technique to monitor density of cold plasma. Circuit resonance monitoring, if properly coupled with impedance measurements and electron beam injection may be very useful, low interference tool for diagnostics of highly structured plasmas like those in auroral region.

An integral condition for core-collapse supernova explosions

DOE PAGES

Murphy, Jeremiah W.; Dolence, Joshua C.

2017-01-10

Here, we derive an integral condition for core-collapse supernova (CCSN) explosions and use it to construct a new diagnostic of explodability. The fundamental challenge in CCSN theory is to explain how a stalled accretion shock revives to explode a star. In this manuscript, we assume that the shock revival is initiated by the delayed-neutrino mechanism and derive an integral condition for spherically symmetric shock expansion, v s > 0. One of the most useful one-dimensional explosion conditions is the neutrino luminosity and mass-accretion rate (more » $${L}_{\

Computer modeling of electrical performance of detonators

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

Furnberg, C.M.; Peevy, G.R.; Brigham, W.P.

1995-05-01

An empirical model of detonator electrical performance which describes the resistance of the exploding bridgewire (EBW) or exploding foil initiator (EFI or slapper) as a function of energy, deposition will be described. This model features many parameters that can be adjusted to obtain a close fit to experimental data. This has been demonstrated using recent experimental data taken with the cable discharge system located at Sandia National Laboratories. This paper will be a continuation of the paper entitled ``Cable Discharge System for Fundamental Detonator Studies`` presented at the 2nd NASA/DOD/DOE Pyrotechnic Workshop.

Use of Ni63 Overvoltage Gap Switches in the Flight Termination Systems on Boosters Launched from U.S. Army Kwajalein Atoll (USAKA)

DTIC Science & Technology

1990-05-01

J3 w c’f oz us~ w - 0n fn 00:1 0 Ic 0 L o 0j 0 0I LL 0 Iof the less than adequate reliability of the earlier Exploding Foil Initiator ( EFI ) design...Action and Alternatives EFI Exploding Foil Initiator Environmental Assessment (EA) A concise public document in which a Federal agency provides...Interceptor (GBI) firing unit (the Explosive Foil Initiator ) was built and tested, it operated unreliably. Many hardware development problems were

Magnetohydrodynamic modelling of exploding foil initiators

NASA Astrophysics Data System (ADS)

Neal, William

2015-06-01

Magnetohydrodynamic (MHD) codes are currently being developed, and used, to predict the behaviour of electrically-driven flyer-plates. These codes are of particular interest to the design of exploding foil initiator (EFI) detonators but there is a distinct lack of comparison with high-fidelity experimental data. This study aims to compare a MHD code with a collection of temporally and spatially resolved diagnostics including PDV, dual-axis imaging and streak imaging. The results show the code's excellent representation of the flyer-plate launch and highlight features within the experiment that the model fails to capture.

Exploding Head Syndrome as Aura of Migraine with Brainstem Aura: A Case Report.

PubMed

Rossi, Fabian H; Gonzalez, Elizabeth; Rossi, Elisa Marie; Tsakadze, Nina

2018-01-01

This article reports a case of exploding head syndrome (EHS) as an aura of migraine with brainstem aura (MBA). A middle-aged man presented with intermittent episodes of a brief sensation of explosion in the head, visual flashing, vertigo, hearing loss, tinnitus, confusion, ataxia, dysarthria, and bilateral visual impairment followed by migraine headache. The condition was diagnosed as MBA. Explosive head sensation, sensory phenomena, and headaches improved over time with nortriptyline. This case shows that EHS can present as a primary aura symptom in patients with MBA.

Numerical simulations of Z-Pinch experiments to create supersonic differentially-rotating plasma flows

NASA Astrophysics Data System (ADS)

Bochi, Matteo; Ummels, Sebastiaan; Chittenden, Jeremy; Lebedev, Sergey

2011-10-01

Recently, it was proposed that a small number of plasma jets produced by lasers could be used to generate a plasma configuration relevant to some features of astrophysical accretion disc physics. We propose complementary experimental configurations which employ converging flows generated in a cylindrical wire array Z-pinch modified to produce a rotating plasma. In this paper we present 3D MHD simulations using the code GORGON which show how this approach can be implemented at the MAGPIE facility at Imperial College, London. We will present the general scenario and the results of a parametric study relating the parameters of the array with the features of the resulting plasma. In particular, we will show how a rotating plasma cylinder or ring, with typical rotation velocity 30 Km/s and Mach number 8 is formed, and how, after about 1-2 revolutions, the material of the plasma ring is ejected in a pair of thermally driven, conical outflows propagating along the rotation axis. We will discuss to what aspects of the physics of accretion discs, the results of such experiments could be relevant. We will also consider the effects of different magnetic configurations, which further expand the possibility to relate the experiments with the astrophysical discs. Experimental implementation of some of these setups is currently in progress on MAGPIE.

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

Niemann, Christoph; Gekelman, W.; Winske, D.

We have performed several thousand high-energy laser shots in the LAPD to investigate the dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma. Debris-ions expanding at super-Alfvenic velocity (up to MA=1.5) expel the ambient magnetic field, creating a large (> 20 cm) diamagnetic cavity. We observed field compressions of up to B/B{sub 0} = 1.5 at the edge of the bubble, consistent with the MHD jump conditions, as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized bymore » the magnetic piston to super-Alfvenic speeds and swept outside the bubble volume. Nonlinear shear-Alfven waves ({delta}B/B{sub 0} > 25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave. While the data is consistent with a weak magneto-sonic shock, the experiments were severely limited by the low ambient plasma densities (10{sup 12} cm{sup -3}). 2D hybrid simulations indicate that future experiments with the new LAPD plasma source and densities in excess of 10{sup 13} cm{sup -3} will drive full-blown collisionless shocks with MA>10 over several c/wpi and shocked Larmor radii. In a separate experiment at the LANL Trident laser facility we have performed a proof-of-principle experiment at higher densities to demonstrate key elements of collisionless shocks in laser-produced magnetized plasmas with important implications to NIF. Simultaneously we have upgraded the UCLA glass-laser system by adding two large amplitude disk amplifiers from the NOVA laser and boost the on-target energy from 30 J to up to 1 kJ, making this one of the world’s largest university-scale laser systems. We now have the infrastructure in place to perform novel and unique high-impact experiments on collision-less shocks at the LAPD.« less

Research and Development for Continued Performance Improvement in Flexible a-Si PV

DTIC Science & Technology

2010-12-14

accomplished, however, at low temperatures silicides tend to form on the surface of the filament, which affected filament lifetime and deposition rate...considered. Titanium Nitride, sputtered As an alternative to the hot wire deposition of silicon, samples were prepared with various thicknesses of...Silicon 21 Insitu DC Sputtering Titanium Nitride 22 Metal Machine 2 ឈ> RF Oxygen Plasma Silicon Dioxide 20. Oxygen Etch Table A.4.1 Open circuit

Modeling of low pressure plasma sources for microelectronics fabrication

NASA Astrophysics Data System (ADS)

Agarwal, Ankur; Bera, Kallol; Kenney, Jason; Likhanskii, Alexandre; Rauf, Shahid

2017-10-01

Chemically reactive plasmas operating in the 1 mTorr-10 Torr pressure range are widely used for thin film processing in the semiconductor industry. Plasma modeling has come to play an important role in the design of these plasma processing systems. A number of 3-dimensional (3D) fluid and hybrid plasma modeling examples are used to illustrate the role of computational investigations in design of plasma processing hardware for applications such as ion implantation, deposition, and etching. A model for a rectangular inductively coupled plasma (ICP) source is described, which is employed as an ion source for ion implantation. It is shown that gas pressure strongly influences ion flux uniformity, which is determined by the balance between the location of plasma production and diffusion. The effect of chamber dimensions on plasma uniformity in a rectangular capacitively coupled plasma (CCP) is examined using an electromagnetic plasma model. Due to high pressure and small gap in this system, plasma uniformity is found to be primarily determined by the electric field profile in the sheath/pre-sheath region. A 3D model is utilized to investigate the confinement properties of a mesh in a cylindrical CCP. Results highlight the role of hole topology and size on the formation of localized hot-spots. A 3D electromagnetic plasma model for a cylindrical ICP is used to study inductive versus capacitive power coupling and how placement of ground return wires influences it. Finally, a 3D hybrid plasma model for an electron beam generated magnetized plasma is used to understand the role of reactor geometry on plasma uniformity in the presence of E  ×  B drift.

Numerical simulation of an oxygen-fed wire-to-cylinder negative corona discharge in the glow regime

NASA Astrophysics Data System (ADS)

Yanallah, K.; Pontiga, F.; Castellanos, A.

2011-02-01

Negative glow corona discharge in flowing oxygen has been numerically simulated for a wire-to-cylinder electrode geometry. The corona discharge is modelled using a fluid approximation. The radial and axial distributions of charged and neutral species are obtained by solving the corresponding continuity equations, which include the relevant plasma-chemical kinetics. Continuity equations are coupled with Poisson's equation and the energy conservation equation, since the reaction rate constants may depend on the electric field and temperature. The experimental values of the current-voltage characteristic are used as input data into the numerical calculations. The role played by different reactions and chemical species is analysed, and the effect of electrical and geometrical parameters on ozone generation is investigated. The reliability of the numerical model is verified by the reasonable agreement between the numerical predictions of ozone concentration and the experimental measurements.

System for phase-contrast x-ray radiography using X pinch radiation and a method thereof

DOEpatents

Chandler, Katherine; Chelkovenko, Tatiana; Hammer, David; Pikuz, Sergei; Sinars, Daniel; Song, Byungmoo

2007-11-06

A radiograph system with an anode plate, a cathode plate, and a power source coupled to said anode plate and the cathode plate. At least two wires coupled between the anode plate and the cathode plate provide a configuration to form an X-pinch having a photon source size of less than five microns at energies above 2.5 keV. Material at the configuration forming the X-pinch vaporizes upon application of a suitable current to the wires forming a dense hot plasma and emitting a single x-ray pulse with sufficient photons having energies in the range of from about 2.5 keV to about 20 keV to provide a phase contrast image of an object in the path of the photons. Multiple simultaneous images may be formed of a plurality of objects. Suitable filters and x-ray detectors are provided.

Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

NASA Astrophysics Data System (ADS)

Stavinoha, Joe N.

The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al-4V alloy substrates. Cylindrical weld metal deposits were built by employing an automatic wire feeder, turntable positioner, and vertical torch positioner. A total of four cylindrical weld metal specimens were built with various combinations of essential plasma arc welding process parameters. The temperature of the weld metal deposit was taken with a thermocouple after allowing a specified amount of time to pass before depositing the next weld track. An analytical heat flow model was created that estimated the temperature of the weld metal deposit in relation to the number of tracks deposited. The analytical heat flow model was adjusted to match the experimental data that was obtained and revealed that the rate of production could be increased if the rate of thermal energy losses from the deposit were increased. Cross-sections of the weld metal deposits were examined to observe the effects of thermal energy input on the weld metal macrostructure, microstructure, and grain size. Results from the metallographic inspections revealed an increase in grain size and coarsening of the structure as the number of weld tracks in the deposit increased.

The Limit of Magnetic-Shear Energy in Solar Active Regions

NASA Technical Reports Server (NTRS)

Moore, Ronald; Falconer, David; Sterling, Alphonse

2012-01-01

It has been found previously, by measuring from active-region magnetograms a proxy of the free energy in the active region's magnetic field, (1) that there is a sharp upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region's magnetic flux content, and (2) that most active regions are near this limit when their field explodes in a coronal mass ejection/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy-limit line in (flux content, free-energy proxy) phase space. Here, we present evidence that specifies the underlying magnetic condition that gives rise to the free-energy limit and the accompanying main sequence of explosive active regions. Using a suitable free-energy proxy measured from vector magnetograms of 44 active regions, we find evidence that (1) in active regions at and near their free-energy limit, the ratio of magnetic-shear free energy to the non-free magnetic energy the potential field would have is of the order of one in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free-energy limit. Evidently, most active regions in which this core-field energy ratio is much less than one cannot be triggered to explode; as this ratio approaches one, most active regions become capable of exploding; and when this ratio is one, most active regions are compelled to explode.

The Limit of Magnetic-Shear Energy in Solar Active Regions

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, David A.; Sterling, Alphonse C.

2013-01-01

It has been found previously, by measuring from active ]region magnetograms a proxy of the free energy in the active region fs magnetic field, (1) that there is a sharp upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) that most active regions are near this limit when their field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main ]sequence path bordering the free ]energy ]limit line in (flux content, free ]energy proxy) phase space. Here we present evidence that specifies the underlying magnetic condition that gives rise to the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free energy proxy measured from vector magnetograms of 44 active regions, we find evidence that (1) in active regions at and near their free ]energy limit, the ratio of magnetic ]shear free energy to the non ]free magnetic energy the potential field would have is of order 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. Evidently, most active regions in which this core ]field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1, most active regions are compelled to explode.

Automated plasma control with optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Ward, P. P.

Plasma etching and desmear processes for printed wiring board (PWB) manufacture are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. These techniques are not real-time methods however, and do not allow for immediate diagnosis and process correction. These tests often require scrapping some fraction of a batch to insure the integrity of the rest. Since these tests verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. These tests are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process anomalies should be detected and corrected before the parts being treated are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored along with applications of this technique to for process control, failure analysis and endpoint determination in PWB manufacture.

Coronal Heating by Magnetic Explosions

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, D. A.; Porter, Jason G.; Suess, Steven T.

1998-01-01

We build a case for the persistent strong coronal heating in active regions and the pervasive quasi-steady heating of the corona in quiet regions and coronal holes being driven in basically the same way as the intense transient heating in solar flares: by explosions of sheared magnetic fields in the cores of initially closed bipoles. We begin by summarizing the observational case for exploding sheared core fields being the drivers of a wide variety of flare events, with and without coronal mass ejections. We conclude that the arrangement of an event's flare heating, whether there is a coronal mass ejection, and the time and place of the ejection relative to the flare heating are all largely determined by four elements of the form and action the magnetic field: (1) the arrangement of the impacted, interacting bipoles participating in the event, (2) which of these bipoles are active (have sheared core fields that explode) and which are passive (are heated by injection from impacted active bipoles), (3) which core field explodes first, and (4) which core-field explosions are confined within the closed field of their bipoles and which ejectively open their bipoles.

Production of D-lactic acid from sugarcane bagasse using steam-explosion

NASA Astrophysics Data System (ADS)

Sasaki, Chizuru; Okumura, Ryosuke; Asakawa, Ai; Asada, Chikako; Nakamura, Yoshitoshi

2012-03-01

This study investigated the production of D-lactic acid from unutilized sugarcane bagasse using steam explosion pretreatment. The optimal steam pressure for a steaming time of 5 min was determined. By enzymatic saccharification using Meicellase, the highest recovery of glucose from raw bagasse, 73.7%, was obtained at a steam pressure of 20 atm. For residue washed with water after steam explosion, the glucose recovery increased up to 94.9% at a steam pressure of 20 atm. These results showed that washing with water is effective in removing enzymatic reaction inhibitors. After steam pretreatment (steam pressure of 20 atm), D-lactic acid was produced by Lactobacillus delbrueckii NBRC 3534 from the enzymatic hydrolyzate of steam-exploded bagasse and washed residue. The conversion rate of D-lactic acid obtained from the initial glucose concentration was 66.6% for the hydrolyzate derived from steam-exploded bagasse and 90.0% for that derived from the washed residue after steam explosion. These results also demonstrated that the hydrolyzate of steam-exploded bagasse (without washing with water) contains fermentation inhibitors and washing with water can remove them.

Improved enzymatic saccharification of steam exploded cotton stalk using alkaline extraction and fermentation of cellulosic sugars into ethanol.

PubMed

Keshav, Praveen K; Naseeruddin, Shaik; Rao, L Venkateswar

2016-08-01

Cotton stalk, a widely available and cheap agricultural residue lacking economic alternatives, was subjected to steam explosion in the range 170-200°C for 5min. Steam explosion at 200°C and 5min led to significant hemicellulose solubilization (71.90±0.10%). Alkaline extraction of steam exploded cotton stalk (SECOH) using 3% NaOH at room temperature for 6h led to 85.07±1.43% lignin removal with complete hemicellulose solubilization. Besides, this combined pretreatment allowed a high recovery of the cellulosic fraction from the biomass. Enzymatic saccharification was studied between steam exploded cotton stalk (SECS) and SECOH using different cellulase loadings. SECOH gave a maximum of 785.30±8.28mg/g reducing sugars with saccharification efficiency of 82.13±0.72%. Subsequently, fermentation of SECOH hydrolysate containing sugars (68.20±1.16g/L) with Saccharomyces cerevisiae produced 23.17±0.84g/L ethanol with 0.44g/g yield. Copyright © 2016 Elsevier Ltd. All rights reserved.

Plasma particle simulations on interactions between spacecraft and cold streaming plasmas

NASA Astrophysics Data System (ADS)

Miyake, Y.; Usui, H.; Nakashima, H.

2012-12-01

In order to better assess space weather effects on spacecraft system, we require in-depth understanding of fundamental processes of spacecraft-plasma interactions. Particularly in scientific spacecraft missions, the wake and photoelectron cloud formation as well as the spacecraft charging are significant factors influencing their operations, because onboard scientific instruments are often susceptible to such plasma disturbances. In this paper, we focus on the wake formation resulting from spacecraft interactions with a cold streaming plasma and study it by means of numerical simulations using modern supercomputers. We apply the particle-in-cell (PIC) method to the study of wake structure around a scientific spacecraft. We use our original plasma particle simulation code EMSES [2], which enables us to include solid spacecraft and sensor surfaces as internal boundaries. Although there are a number of preceding PIC simulation works regarding the wake structure behind a spacecraft [3], we here extend the studies by including numerical models of both spacecraft body and conducting booms simultaneously in the simulation system. The current analysis focuses on the wake structures behind the Cluster satellite in a tenuous plasma flow. We have included the conducting surfaces of wire booms as well as the spacecraft body in the simulations, the both of which can contribute to the wake formation. The major outcomes of the simulations are summarized as follows [4]; 1. not only a spacecraft body but also a thin (in an order of mm) wire boom contribute substantially to the formation of an electrostatic wake, particularly when the spacecraft has a positive potential of a few tens of volts; 2. in such a condition, the spatial scale of the wake reaches up to 100 m, leading to the detection of a wake electric field pattern that is very similar to that observed in the presence of a uniform ambient electric field; 3. spurious electric field can be detected even in subsonic ion flows occasionally, which is caused by an asymmetric potential pattern between the up- and down- streams of the spacecraft. We will report some details of these results as well as the comparison of the numerical results with observational data. [References] [1] André, M., and C. M. Cully (2012), Low-energy ions: A previously hidden solar system particle population, Geophys. Res. Lett., 39, L03101, doi:10.1029/ 2011GL050242. [2] Miyake, Y., and H. Usui (2009), New electromagnetic particle simulation code for the analysis of spacecraft-plasma interactions, Phys. Plasmas, 16, 062904, doi:10.1063/1.3147922. [3] Engwall, E., A. I. Eriksson, and J. Forest (2006), Wake formation behind positively charged spacecraft in flowing tenuous plasmas, Phys. Plasmas, 13, 062904, doi:10.1063/1.2199207. [4] Miyake, Y., and H. Usui (2012), Particle simulations of wake effects on electric field measurements in multi-species ion flows, Proc. of 12th Spacecraft Charging Technology Conference, Kitakyushu, Japan.

Dynamics of Single Flux Rope in the Reconnection Scaling Experiment

NASA Astrophysics Data System (ADS)

Feng, Y.; Sears, J.; Intrator, T.; Weber, T.; Swan, H.; Dunn, J. P.; Gao, K.; Chapdelaine, L.

2013-12-01

A magnetic flux tube threaded by current is a flux rope with helically twisted field lines. In the Reconnection Scaling Experiment (RSX) we use a plasma gun to generate a single flux rope with a choice of axial boundary conditions. If this flux rope is driven hard enough, i.e., when J●B /B2 is larger than the kink instability threshold, we measure a helically distorted kinked structure. Rather than exploding in an Alfvén time, this kink appears to saturate to a steady amplitude, helical, gyrating flux rope, which persists as long as the plasma gun sources the current. To understand it, we have experimentally measured three-dimensional (3D) profiles of various quantities of this flux rope. These quantities include magnetic field B, plasma density n and potential φ, ion flow velocity vi, so that current density J, electron flow velocity ve and electron pressure Pe can also be derived. Consequently we can analyze the single flux rope dynamics systematically in 3D. Besides gyrating (writhe), we also find the flux rope has a spin (twist) center, around which the J×B - ▽Pe ≠ 0 suggesting that there should be other forces for the radial balance. We also find that there is a reverse current moving around with the flux rope at some locations, i.e. there are local induced currents that are not at all apparent from measurements outside the 3D volume. Work supported by LANL-DOE, DOE Fusion Energy Sciences DE-AC52-06NA25396, NASA Geospace NNHIOA044I Basic, CMSO, SULI, NUF.

Functionalization and characterization of pyrolyzed polymer based carbon microstructures for bionanoelectronics platforms

NASA Astrophysics Data System (ADS)

Hirabayashi, Mieko; Mehta, Beejal; Vahidi, Nasim W.; Khosla, Ajit; Kassegne, Sam

2013-11-01

In this study, the investigation of surface-treatment of chemically inert graphitic carbon microelectrodes (derived from pyrolyzed photoresist polymer) for improving their attachment chemistry with DNA molecular wires and ropes as part of a bionanoelectronics platform is reported. Polymer microelectrodes were fabricated on a silicon wafer using standard negative lithography procedures with negative-tone photoresist. These microelectrode structures were then pyrolyzed and converted to a form of conductive carbon that is referred to as PP (pyrolyzed polymer) carbon throughout this paper. Functionalization of the resulting pyrolyzed structures was done using nitric, sulfuric, 4-amino benzoic acids (4-ABA), and oxygen plasma etching and the surface modifications confirmed with Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and electron dispersion x-ray spectroscopy (EDS). Post surface-treatment analysis of microelectrodes with FTIR and Raman spectroscopy showed signature peaks characteristics of carboxyl functional groups while EDS showed an increase in oxygen content in the surface-treatment procedures (except 4-ABA) indicating an increase in carboxyl functional group. These functional groups form the basis for peptide bond with aminated oligonucleotides that in turn could be used as molecular wires and interconnects in a bionanoelectronics platform. Post-pyrolysis analysis using EDS showed relatively higher oxygen concentrations at the edges and location of defects compared to other locations on these microelectrodes. In addition, electrochemical impedance measurements showed metal-like behavior of PP carbon with high conductivity (|Z| <1 KΩ) and no detectable detrimental effect of oxygen plasma surface-treatment on electrical characteristic. In general, characterization results—taken together—indicated that oxygen plasma surface-treatment produced more reliable, less damaging, and consistently repeatable generation of carboxyl functional groups than diazonium salt and strong acid treatments.

Spectroscopy of materials for terahertz photonics

NASA Astrophysics Data System (ADS)

Postava, K.; Chochol, J.; Mičica, M.; Vanwolleghem, M.; Kolejak, P.; Halagačka, L.; Cada, M.; Pištora, J.; Lampin, J.-F.

2016-12-01

In this paper we apply the terahertz time-domain spectroscopy (THz-TDS) to obtain optical function spectra in the range from 0.06 to 3 THz. Polarization sensitivity is obtained using azimuth-controlled wire-grid polarizers. We demonstrate general methods on characterization of plasmonic semiconductors. Detail characterization of optical and magneto-optical material properties is also motivated by a need of optical isolator in THz spectral range. The technique is applied to III-V semiconductors. The typical material is a single crystal undoped InSb having the plasma frequency in the range of interest. With appropriate magnetic field (in our case 0.4 T) we observed coupling of plasma and cyclotron behavior of free electrons with gigantic magneto-optic effect in the THz spectral range.

Systems and methods for imaging using radiation from laser produced plasmas

DOEpatents

Renard-Le Galloudec, Nathalie; Cowan, Thomas E.; Sentoku, Yasuhiko; Rassuchine, Jennifer

2009-06-30

In particular embodiments, the present disclosure provides systems and methods for imaging a subject using radiation emitted from a laser produced plasma generating by irradiating a target with a laser. In particular examples, the target includes at least one radiation enhancing component, such as a fluor, cap, or wire. In further examples, the target has a metal layer and an internal surface defining an internal apex, the internal apex of less than about 15 .mu.m, such as less than about 1 .mu.m. The targets may take a variety of shapes, including cones, pyramids, and hemispheres. Certain aspects of the present disclosure provide improved imaging of a subject, such as improved medical images of a radiation dose than typical conventional methods and systems.

Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas.

PubMed

Dutra, E C; Koch, J A; Presura, R; Angermeier, W A; Darling, T; Haque, S; Mancini, R C; Covington, A M

2016-11-01

Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

X-ray Heating and Electron Temperature of Laboratory Photoionized Plasmas

NASA Astrophysics Data System (ADS)

Mancini, Roberto; Lockard, Tom; Mayes, Daniel C.; Loisel, Guillaume; Bailey, James E.; Rochau, Gregory; Abdallah, J.; Golovkin, I.

2018-06-01

In separate experiments performed at the Z facility of Sandia National Laboratories two different samples were employed to produce and characterize photoionized plasmas. One was a gas cell filled with neon, and the other was a thin silicon layer coated with plastic. Both samples were driven by the broadband x-ray flux produced at the collapse of a wire array z-pinch implosion. Transmission spectroscopy of a narrowband portion of the x-ray flux was used to diagnose the charge state distribution, and the electron temperature was extracted from a Li-like ion level population ratio. To interpret the temperature measurement, we performed Boltzmann kinetics and radiation-hydrodynamic simulations. We found that non-equilibrium atomic physics and the coupling of the radiation flux to the atomic level population kinetics play a critical role in modeling the x-ray heating of photoionized plasmas. In spite of being driven by similar x-ray drives, differences of ionization and charged state distributions in the neon and silicon plasmas are reflected in the plasma heating and observed electron temperatures.This work was sponsored in part by DOE Office of Science Grant DE-SC0014451, and the Z Facility Fundamental Science Program of SNL.

An investigation of conducted and radiated emissions from a hollow-cathode plasma contactor

NASA Astrophysics Data System (ADS)

Buchholtz, Brett W.; Wilbur, Paul J.

1993-07-01

An investigation conducted on the electrical interference induced by the operation of a hollow-cathode plasma contractor in a ground-based facility is described. The types of electrical interference, or noise, which are important to Space Station Freedom designers are classified as either conducted or radiated emissions. The procedures required to perform conducted and radiated emission measurements on a plasma contactor are examined. The experimental data obtained are typically examined in the frequency domain (i.e. amplitudes of the noise fluctuations versus frequency). Results presented indicate the conducted emissions, which are the current fluctuations from the contactor into the space station wiring, are affected by operating parameters such as expellant flow rate and discharge current. The radiated emissions, which are the electromagnetic waves induced and emitted by the contactor, appear to be influenced by the contactor emission current. Other experimental results suggest possible sources which are responsible for the observed noise. For example, the influence of the plasma environment downstream from the contactor on noise emission levels is described. In addition, a brief discussion is given on the correlation between conducted and radiated emissions and the mechanisms through which both are influenced by the plasma downstream of the contactor.

An investigation of conducted and radiated emissions from a hollow-cathode plasma contactor

NASA Technical Reports Server (NTRS)

Buchholtz, Brett W.; Wilbur, Paul J.

1993-01-01

An investigation conducted on the electrical interference induced by the operation of a hollow-cathode plasma contractor in a ground-based facility is described. The types of electrical interference, or noise, which are important to Space Station Freedom designers are classified as either conducted or radiated emissions. The procedures required to perform conducted and radiated emission measurements on a plasma contactor are examined. The experimental data obtained are typically examined in the frequency domain (i.e. amplitudes of the noise fluctuations versus frequency). Results presented indicate the conducted emissions, which are the current fluctuations from the contactor into the space station wiring, are affected by operating parameters such as expellant flow rate and discharge current. The radiated emissions, which are the electromagnetic waves induced and emitted by the contactor, appear to be influenced by the contactor emission current. Other experimental results suggest possible sources which are responsible for the observed noise. For example, the influence of the plasma environment downstream from the contactor on noise emission levels is described. In addition, a brief discussion is given on the correlation between conducted and radiated emissions and the mechanisms through which both are influenced by the plasma downstream of the contactor.

In-Flight and Post-Flight Impact Data Analysis from DEBIE2 (Debris In-Orbit Evaluator) on Board of ISS

NASA Astrophysics Data System (ADS)

Menicucci, Alessandra; Drolshagen, Gerhard; Kuitunen, Juha; Butenko, Yuriy; Mooney, Cathal

2013-08-01

DEBIE2 (Debris-in-orbit-evaluator) was launched in February 2008 as part of the European Technology Exposure Facility (EuTEF) and installed on the exterior of Columbus on ISS. DEBIE2 is an active detector, composed by 3 sensor units able to monitor the sub-micron micro-meteoroid and debris population in space. Each DEBIE sensor consists of a thin aluminium foil coupled with 2 wire grids sensitive to the plasma generated by particles impacting on the foil where also 2 piezoelectric sensors are glued. If the particle penetrates the foil, this can be detected by a third electron plasma detector located just behind the foil. The combination of these information allows to estimate the micro-particles and debris fluxes. EuTEF and DEBIE2 were retrieved after 18 months in flight and returned to Earth with the Space Shuttle Mission STS-128. In this paper, the results of the analysis of in-flight impact data are presented as well as the comparison with the models. The DEBIE2 sensor pointing the Zenith direction, was found to have one wire of the upper grid cut in two pieces by an impact. The postflight analysis focused on this sensor and included optical and SEM/EDX scanning. The results from this inspection will be also presented in this paper.

Grid-Sphere Electrodes for Contact with Ionospheric Plasma

NASA Technical Reports Server (NTRS)

Stone, Nobie H.; Poe, Garrett D.

2010-01-01

Grid-sphere electrodes have been proposed for use on the positively biased end of electrodynamic space tethers. A grid-sphere electrode is fabricated by embedding a wire mesh in a thin film from which a spherical balloon is formed. The grid-sphere electrode would be deployed from compact stowage by inflating the balloon in space. The thin-film material used to inflate the balloon is formulated to vaporize when exposed to the space environment. This would leave the bare metallic spherical grid electrode attached to the tether, which would present a small cross-sectional area (essentially, the geometric wire shadow area only) to incident neutral atoms and molecules. Most of the neutral particles, which produce dynamic drag when they impact a surface, would pass unimpeded through the open grid spaces. However, partly as a result of buildup of a space charge inside the grid-sphere, and partially, the result of magnetic field effects, the electrode would act almost like a solid surface with respect to the flux of electrons. The net result would be that grid-sphere electrodes would introduce minimal aerodynamic drag, yet have effective electrical-contact surface areas large enough to collect multiampere currents from the ionospheric plasma that are needed for operation of electrodynamic tethers. The vaporizable-balloon concept could also be applied to the deployment of large radio antennas in outer space.

Power density measurements to optimize AC plasma jet operation in blood coagulation.

PubMed

Ahmed, Kamal M; Eldeighdye, Shaimaa M; Allam, Tarek M; Hassanin, Walaa F

2018-06-14

In this paper, the plasma power density and corresponding plasma dose of a low-cost air non-thermal plasma jet (ANPJ) device are estimated at different axial distances from the nozzle. This estimation is achieved by measuring the voltage and current at the substrate using diagnostic techniques that can be easily made in laboratory; thin wire and dielectric probe, respectively. This device uses a compressed air as input gas instead of the relatively-expensive, large-sized and heavy weighed tanks of Ar or He gases. The calculated plasma dose is found to be very low and allows the presented device to be used in biomedical applications (especially blood coagulation). While plasma active species and charged-particles are found to be the most effective on blood coagulation formation, both air flow and UV, individually, do not have any effect. Moreover, optimal conditions for accelerating blood coagulation are studied. Results showed that, the power density at the substrate is shown to be decreased with increasing the distance from the nozzle. In addition, both distances from nozzle and air flow rate play an important role in accelerating blood coagulation process. Finally, this device is efficient, small-sized, safe enough, of low cost and, hence, has its chances to be wide spread as a first aid and in ambulance.

Analysis Commons, A Team Approach to Discovery in a Big-Data Environment for Genetic Epidemiology

PubMed Central

Brody, Jennifer A.; Morrison, Alanna C.; Bis, Joshua C.; O'Connell, Jeffrey R.; Brown, Michael R.; Huffman, Jennifer E.; Ames, Darren C.; Carroll, Andrew; Conomos, Matthew P.; Gabriel, Stacey; Gibbs, Richard A.; Gogarten, Stephanie M.; Gupta, Namrata; Jaquish, Cashell E.; Johnson, Andrew D.; Lewis, Joshua P.; Liu, Xiaoming; Manning, Alisa K.; Papanicolaou, George J.; Pitsillides, Achilleas N.; Rice, Kenneth M.; Salerno, William; Sitlani, Colleen M.; Smith, Nicholas L.; Heckbert, Susan R.; Laurie, Cathy C.; Mitchell, Braxton D.; Vasan, Ramachandran S.; Rich, Stephen S.; Rotter, Jerome I.; Wilson, James G.; Boerwinkle, Eric; Psaty, Bruce M.; Cupples, L. Adrienne

2017-01-01

Summary paragraph The exploding volume of whole-genome sequence (WGS) and multi-omics data requires new approaches for analysis. As one solution, we have created a cloud-based Analysis Commons, which brings together genotype and phenotype data from multiple studies in a setting that is accessible by multiple investigators. This framework addresses many of the challenges of multi-center WGS analyses, including data sharing mechanisms, phenotype harmonization, integrated multi-omics analyses, annotation, and computational flexibility. In this setting, the computational pipeline facilitates a sequence-to-discovery analysis workflow illustrated here by an analysis of plasma fibrinogen levels in 3996 individuals from the National Heart, Lung, and Blood Institute (NHLBI) Trans-Omics for Precision Medicine (TOPMed) WGS program. The Analysis Commons represents a novel model for transforming WGS resources from a massive quantity of phenotypic and genomic data into knowledge of the determinants of health and disease risk in diverse human populations. PMID:29074945

Characterization of Imposed Ordered Structures in MDPX

NASA Astrophysics Data System (ADS)

Hall, Taylor; Thomas, Edward; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene

2016-10-01

It is well understood that the microparticles in complex, or dusty, plasmas will form self-consistent crystalline patterns at the proper plasma parameters. In the Magnetized Dusty Plasma Experiment (MDPX) device, studies have been made of imposed, ordered structuring of the dust particles to a two dimensional grid. At high magnetic field (B >1 Tesla), the dust particles are shown to become spatially oriented to the structure of a wire mesh embedded in an electrically floating, upper electrode while the particles are suspended in a plasma that is generated by the powered, lower electrode in the experiment. With even higher magnetic field (B >2 Tesla), the particles become strongly confined to the mesh pattern with the particles constrained to a quasi-discreet motion that closely follows the mesh pattern. This presentation characterizes the structure of the potential energy well in which the dust particles are trapped through observation of particle motion and measurement of the thermal properties of the particles. This work is supported by funding from the U. S. Department of Energy Grant Number DE - SC0010485 and the NASA/Jet Propulsion Laboratory, JPL-1543114.

Development of nanostructures on plasma facing components

NASA Astrophysics Data System (ADS)

Ruzic, David; Fiflis, Peter; Kalathiparambil, Kishor Kumar

2015-11-01

Exposure to low temperature helium plasma, with parameters similar to tokamak edge plasmas, have been found to induce the growth of nanostructures on tungsten. These nanostructures results in an increase in the effective surface area, and will alter the physical properties of the components. Although this has several potential applications in the industrial scenario, it is an undesired effect for fusion reactor components, and is hence necessary to understand their growth mechanisms in order to figure out suitable remedial schemes. Work done using a high density, low temperature helicon discharge plasma source with a resistively heated tungsten wire immersed in the discharge as the substrate have demonstrated the well-defined stages of the growth as a function of total fluence. The required fluence was attained by extending the exposure time. Extensive research work has also shown that a variety of other materials are also prone to develop such structures under similar conditions. In the present work, the effect of the experimental conditions on the various stages of structure development will be presented and a comparison between the structures developed on different types of substrates will be shown.

Protons and how they are transported by proton pumps.

PubMed

Buch-Pedersen, M J; Pedersen, B P; Veierskov, B; Nissen, P; Palmgren, M G

2009-01-01

The very high mobility of protons in aqueous solutions demands special features of membrane proton transporters to sustain efficient yet regulated proton transport across biological membranes. By the use of the chemical energy of ATP, plasma-membrane-embedded ATPases extrude protons from cells of plants and fungi to generate electrochemical proton gradients. The recently published crystal structure of a plasma membrane H(+)-ATPase contributes to our knowledge about the mechanism of these essential enzymes. Taking the biochemical and structural data together, we are now able to describe the basic molecular components that allow the plasma membrane proton H(+)-ATPase to carry out proton transport against large membrane potentials. When divergent proton pumps such as the plasma membrane H(+)-ATPase, bacteriorhodopsin, and F(O)F(1) ATP synthase are compared, unifying mechanistic premises for biological proton pumps emerge. Most notably, the minimal pumping apparatus of all pumps consists of a central proton acceptor/donor, a positively charged residue to control pK(a) changes of the proton acceptor/donor, and bound water molecules to facilitate rapid proton transport along proton wires.

Electromagnetic characteristic of twin-wire indirect arc welding

NASA Astrophysics Data System (ADS)

Shi, Chuanwei; Zou, Yong; Zou, Zengda; Wu, Dongting

2015-01-01

Traditional welding methods are limited in low heat input to workpiece and high welding wire melting rate. Twin-wire indirect arc(TWIA) welding is a new welding method characterized by high melting rate and low heat input. This method uses two wires: one connected to the negative electrode and another to the positive electrode of a direct-current(DC) power source. The workpiece is an independent, non-connected unit. A three dimensional finite element model of TWIA is devised. Electric and magnetic fields are calculated and their influence upon TWIA behavior and the welding process is discussed. The results show that with a 100 A welding current, the maximum temperature reached is 17 758 K, arc voltage is 14.646 V while maximum current density was 61 A/mm2 with a maximum Lorene force of 84.5 μN. The above mentioned arc parameters near the cathode and anode regions are far higher than those in the arc column region. The Lorene force is the key reason for plasma velocity direction deviated and charged particles flowed in the channel formed by the cathode, anode and upper part of arc column regions. This led to most of the energy being supplied to the polar and upper part of arc column regions. The interaction between electric and magnetic fields is a major determinant in shaping TWIA as well as heat input on the workpiece. This is a first study of electromagnetic characteristics and their influences in the TWIA welding process, and it is significant in both a theoretical and practical sense.

Rail damage in a solid-armature rail gun. Final report

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

Brassard, T.; Homan, C.G.

1987-12-01

Plasma-arc-drive rail guns operate by forming a high-temperature plasma behind the projectile using a thin metal fuze. These systems achieve the highest projectile velocities (about 12 km /sec), since the driving force includes a substantial plasma pressure as well as the electromagnetic or Lorentz force. Unfortunately, severe rail damage occurs primarily from the intense temperatures generated by the plasma arc and the wiping motion of the armature itself. The solid-armature gun replaces the plasma armature with a conducting metal armature. Since the plasma arcing is reduced or eliminated, the projectiles are accelerated mainly by the Lorentz force. Thus, solid armaturemore » rail guns operate at lower projectile velocities. The important tradeoff is that there is a substantial reduction in rail damage for metal armature projectiles. The elimination of the plasma force limits projectile velocities in the metal-armature rail guns. A more-subtle limit is the speed at which the commutation process can take place. Although the latter limit is still not well understood, experimental evidence indicates a commutation limit may occur near 6 to 7 km/sec. This velocity limit is still attractive for Army tactical missions for rail guns. The actual rail damage occurring with two types of metal armatures, wire brush contactors and monolithic metal contactors, and new developments in barrel technology, such as superconducting augmentation, are presented in this report.« less

Chromospheric impact of an exploding solar granule

NASA Astrophysics Data System (ADS)

Fischer, C. E.; Bello González, N.; Rezaei, R.

2017-06-01

Context. Observations of multi-wavelength and therefore height-dependent information following events throughout the solar atmosphere and unambiguously assigning a relation between these rapidly evolving layers are rare and difficult to obtain. Yet, they are crucial for our understanding of the physical processes that couple the different regimes in the solar atmosphere. Aims: We characterize the exploding granule event with simultaneous observations of Hinode spectroplarimetric data in the solar photosphere and Hinode broadband Ca II H images combined with Interface Region Imaging Spectrograph (IRIS) slit spectra. We follow the evolution of an exploding granule and its connectivity throughout the atmosphere and analyze the dynamics of a magnetic element that has been affected by the abnormal granule. Methods: In addition to magnetic flux maps we use a local correlation tracking method to infer the horizontal velocity flows in the photosphere and apply a wavelet analysis on several IRIS chromospheric emission features such as Mg II k2v and Mg II k3 to detect oscillatory phenomena indicating wave propagation. Results: During the vigorous expansion of the abnormal granule we detect radially outward horizontal flows, causing, together with the horizontal flows from the surrounding granules, the magnetic elements in the bordering intergranular lanes to be squeezed and elongated. In reaction to the squeezing, we detect a chromospheric intensity and velocity oscillation pulse which we identify as an upward traveling hot shock front propagating clearly through the IRIS spectral line diagnostics of Mg II h&k. Conclusions: Exploding granules can trigger upward-propagating shock fronts that dissipate in the chromosphere. Movies associated to Figs. A.1 and A.2 are available in electronic form at http://www.aanda.org

Radiographic research of the Bi plasma jet formed by the vacuum arc discharge

NASA Astrophysics Data System (ADS)

Artyomov, A. P.; Rousskikh, A. G.; Fedunin, A. V.; Chaikovsky, S. A.; Zhigalin, A. S.; Oreshkin, V. I.

2017-05-01

The results of experiments on a soft x-ray radiography (≈ 1-2 keV) of a bismuth plasma formed by the high-current vacuum arc discharge are represented. The plasma gun with the arc current ≈ 60 kA and the current rise time ≈ 7 μs was used to produce the Bi plasma jet. The compact pulsed radiograph XPG-1 (250 kA, 220 ns) with an X-pinch load consisting of four Mo wires with a diameter 25 μm was used as a source of the soft X-ray radiation. The X-ray backlighting images of the researched plasma jet and the Bi step-wedge with a step thickness of ≈ 100 nm were recorded simultaneously in the course of the experiment. A comparison of the plasma jet x-ray image with the current trace has enabled to estimate dependencies of the linear mass on the arc current. The experiments have shown that when the arc current density reaches ≈ 3·105 A/cm2, the evaporation rate of the electrode material reaches ≈ 100 μg/μs, that under the plasma velocity ≈ 0.5 cm/μs, provides a plasma jet linear mass ≈ 200 μg/cm. At a distance of ≈ 1-2 mm from the arc cathode surface, the sharp increase of the jet linear mass (up to ≈ 500 μg/cm) occurred.

TAZ-8A Alloy Increases The Thermal Endurance Of Steel

NASA Technical Reports Server (NTRS)

Waters, William J.

1990-01-01

TAZ-8A exhibits high strength at temperatures as high as 1,400 degrees F (760 degrees C) and resistance to oxidation; also exhibits excellent cyclic shock resistance between 600 and 2,000 degrees F (316 and 1,093 degrees C) and superplasticity at 1,800 degrees F (982 degrees C). Converts into fine powder and then flame-, plasma-, arc-, or wire-sprayed onto inexpensive steel substrate. Surface treatment with this alloy prolongs service life and reduces costs.

Investigation of Plasma Phenomena in the Ionosphere Under Natural Conditions and Under Conditions Artificially Perturbed by HAARP

DTIC Science & Technology

2008-08-31

fabricated, the concept was tested , and a number of design defects were discovered, a usual occurrence. The test board was modified with cuts and...jumper wires to correct the defects and continue testing until the design was verified. Based on the testing , new artwork was prepared. Note that...mobile data was roughly similar to the fixed station data. It also revealed a circuit design defect that required further testing at the Bellevue

Electrolytic Reduction of Titania Slag in Molten Calcium Chloride Bath

NASA Astrophysics Data System (ADS)

Mohanty, Jayashree

2012-05-01

Ferro-titanium is prepared by direct electrolytic reduction of titania-rich slag obtained from plasma smelting of ilmenite in molten CaCl2. The product after electro-reduction is characterized by x-ray diffraction, scanning electron microscopy, and electron probe microanalysis. The electrolysis is carried out at a cell voltage of 3.0 V, taking graphite as the electrolysis cell as well as the anode, and a titania-rich slag piece wrapped by a nichrome wire is used as the cathode.

Advanced Radiation Theory Support Annual Report 2003, Final Report

DTIC Science & Technology

2004-04-19

diameter wires would lose a higher mass fraction. Table 2. Energy Transfers for Ti Loads Dia. & Case H 2 H13 Mass -a-m Z,DE kJ kJ Pg 1000 - Z 428.2...issues covered are (1) issues and directions for future research, (2) zero- and one-dimensional modeling of DQ experiments, (3) enhanced energy ...coupling and x-ray emission in z-pinch implosions, (4) confinement and compression of magnetic flux by plasma shells, and (6) flashover and energy coupling

Investigation of ion kinetic effects in direct-drive exploding-pusher implosions at the NIF

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

Rosenberg, M. J., E-mail: mrosenbe@mit.edu; Zylstra, A. B.; Séguin, F. H.

Measurements of yield, ion temperature, areal density (ρR), shell convergence, and bang time have been obtained in shock-driven, D{sub 2} and D{sup 3}He gas-filled “exploding-pusher” inertial confinement fusion (ICF) implosions at the National Ignition Facility to assess the impact of ion kinetic effects. These measurements probed the shock convergence phase of ICF implosions, a critical stage in hot-spot ignition experiments. The data complement previous studies of kinetic effects in shock-driven implosions. Ion temperature and fuel ρR inferred from fusion-product spectroscopy are used to estimate the ion-ion mean free path in the gas. A trend of decreasing yields relative to themore » predictions of 2D DRACO hydrodynamics simulations with increasing Knudsen number (the ratio of ion-ion mean free path to minimum shell radius) suggests that ion kinetic effects are increasingly impacting the hot fuel region, in general agreement with previous results. The long mean free path conditions giving rise to ion kinetic effects in the gas are often prevalent during the shock phase of both exploding pushers and ablatively driven implosions, including ignition-relevant implosions.« less

The exploded hand syndrome: a report of five industrial injury cases.

PubMed

Al-Qattan, M M

2013-10-01

The term 'exploded hand syndrome' refers to a specific type of crush injury to the hand in which a high compressive force excessively flattens the hand leading to thenar muscle extrusion through burst lacerations. Out of 89 crushed hands seen over a period of seven years, only five had exploded hand syndrome. They were all male industrial workers ranging in age between 24 and 55 years. All patients had thenar muscle extrusion. Other concurrent injuries included fractures/dislocations, compartment syndrome, and ischaemia. All patients were treated by excision of the extruded intrinsic muscles, as well as primary management of concurrent injuries. All patients had functional assessment including: motor power and sensory testing, range of motion of hand joints, and the quick DASH score. Objective testing showed reduced sensibility in the thumb, reduced grip strength (mean 52% of contralateral hand), reduced pinch strength (mean of 27% of contralateral hand), reduced thumb opposition (the mean Kapandji Score was 5 out of 10), and deficits in the range of motion of the metacarpophalangeal and interphalangeal joints of the thumb. The quick DASH score ranged from 11 to 49 and only two patients were able to go back to regular manual work.

A Test Study to Display Buried Anti-Tank Landmines with GPR and Research Soil Characteristics with CRS

NASA Astrophysics Data System (ADS)

Kadioglu, Selma; Kagan Kadioglu, Yusuf

2014-05-01

An anti-tank mine (AT mine) is a type of land mine designed to damage or destroy vehicles including tanks and armored fighting vehicles. Anti-tank mines typically have a much larger explosive charge, and a fuze designed only to be triggered by vehicles or, in some cases, tampering with the mine. There are a lot of AT mine types. In our test study, MK4 and MK5 AT mine types has been used. The Mk 5 was a cylindrical metal cased U.K. anti-tank blast mine that entered service in 1943, during the Second World War. General Specifications of them are 203 mm diameter, 127 mm height, 4.4-5.7 kg weight, 2.05-3.75 kg of TNT explosive content and 350 lbs operating pressure respectively. The aims of the test study were to image anti-tank landmine with GPR method and to analyse the soil characteristics before the mines made explode and after made be exploded and determine changing of the soil characteristics. We realized data measurement on the real 6 unexploded anti-tank landmine buried approximately 15 cm in depth. The mines spaced 3 m were buried in two lines. Space between lines was 1.5 m. We gathered data on the profiles, approximately 7 m, with a Ramac CUII system and 800 MHz shielded antenna. We collected soil samples on the mines, near and around the mines, on the area in village. We collected soil samples before exploding and after exploding mines. We imaged anti-tank landmines on the depth slices of the GPR data and in their interactive transparent 3D subsets successfully. We used polarized microscope and confocal Raman spectroscopy (CRS) to identify soil characteristic before and after exploitation. The results presented that GPR method and its 3D imaging were successful to determine AT mines, and there was no important changing on mineralogical and petrographical characterization of the soil before and after exploding processing. This project has been supported by Ankara University under grant no 11B6055002. The study is a contribution to the EU funded COST action TU1208, "Civil Engineering Applications of Ground penetrating Radar".

Valorization of lignin and cellulose in acid-steam-exploded corn stover by a moderate alkaline ethanol post-treatment based on an integrated biorefinery concept.

PubMed

Yang, Sheng; Zhang, Yue; Yue, Wen; Wang, Wei; Wang, Yun-Yan; Yuan, Tong-Qi; Sun, Run-Cang

2016-01-01

Due to the unsustainable consumption of fossil resources, great efforts have been made to convert lignocellulose into bioethanol and commodity organic compounds through biological methods. The conversion of cellulose is impeded by the compactness of plant cell wall matrix and crystalline structure of the native cellulose. Therefore, appropriate pretreatment and even post-treatment are indispensable to overcome this problem. Additionally, an adequate utilization of coproduct lignin will be important for improving the economic viability of modern biorefinery industries. The effectiveness of moderate alkaline ethanol post-treatment on the bioconversion efficiency of cellulose in the acid-steam-exploded corn stover was investigated in this study. Results showed that an increase of the alcoholic sodium hydroxide (NaOH) concentration from 0.05 to 4% led to a decrease in the lignin content in the post-treated samples from 32.8 to 10.7%, while the cellulose digestibility consequently increased. The cellulose conversion of the 4% alcoholic NaOH integrally treated corn stover reached up to 99.3% after 72 h, which was significantly higher than that of the acid steam exploded corn stover without post-treatment (57.3%). In addition to the decrease in lignin content, an expansion of cellulose I lattice induced by the 4% alcoholic NaOH post-treatment played a significant role in promoting the enzymatic hydrolysis of corn stover. More importantly, the lignin fraction (AL) released during the 4% alcoholic NaOH post-treatment and the lignin-rich residue (EHR) remained after the enzymatic hydrolysis of the 4% alcoholic NaOH post-treated acid-steam-exploded corn stover were employed to synthesize lignin-phenol-formaldehyde (LPF) resins. The plywoods prepared with the resins exhibit satisfactory performances. An alkaline ethanol system with an appropriate NaOH concentration could improve the removal of lignin and modification of the crystalline structure of cellulose in acid-steam-exploded corn stover, and consequently significantly improve the conversion of cellulose through enzymatic hydrolysis for biofuel production. The lignin fractions obtained as byproducts could be applied in high performance LPF resin preparation. The proposed model for the integral valorization of corn stover in this study is worth of popularization.

Plasma etching of superconducting Niobium tips for scanning tunneling microscopy

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

Roychowdhury, A.; Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742; Dana, R.

We have developed a reproducible technique for the fabrication of sharp superconducting Nb tips for scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. Sections of Nb wire with 250 μm diameter are dry etched in an SF₆ plasma in a Reactive Ion Etcher. The gas pressure, etching time, and applied power are chosen to control the ratio of isotropic to anisotropic etch rates and produce the desired tip shape. The resulting tips are atomically sharp, with radii of less than 100 nm, mechanically stable, and superconducting. They generate good STM images and spectroscopy on single crystal samples of Au(111), Au(100),more » and Nb(100), as well as a doped topological insulator Bi₂Se₃ at temperatures ranging from 30 mK to 9 K.« less

Additional extensions to the NASCAP computer code, volume 3

NASA Technical Reports Server (NTRS)

Mandell, M. J.; Cooke, D. L.

1981-01-01

The ION computer code is designed to calculate charge exchange ion densities, electric potentials, plasma temperatures, and current densities external to a neutralized ion engine in R-Z geometry. The present version assumes the beam ion current and density to be known and specified, and the neutralizing electrons to originate from a hot-wire ring surrounding the beam orifice. The plasma is treated as being resistive, with an electron relaxation time comparable to the plasma frequency. Together with the thermal and electrical boundary conditions described below and other straightforward engine parameters, these assumptions suffice to determine the required quantities. The ION code, written in ASCII FORTRAN for UNIVAC 1100 series computers, is designed to be run interactively, although it can also be run in batch mode. The input is free-format, and the output is mainly graphical, using the machine-independent graphics developed for the NASCAP code. The executive routine calls the code's major subroutines in user-specified order, and the code allows great latitude for restart and parameter change.

Development of a 1-m plasma source for heavy ion beam charge neutralization

NASA Astrophysics Data System (ADS)

Efthimion, Philip C.; Gilson, Erik P.; Grisham, Larry; Davidson, Ronald C.; Yu, Simon; Waldron, William; Grant Logan, B.

2005-05-01

Highly ionized plasmas are being employed as a medium for charge neutralizing heavy ion beams in order to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ˜0.1-1 m would be suitable for achieving a high level of charge neutralization. A radio frequency (RF) source was constructed at the Princeton Plasma Physics Laboratory (PPPL) in support of the joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization. Pulsing the source enabled operation at pressures ˜10 -6 Torr with plasma densities of 10 11 cm -3. Near 100% ionization was achieved. The plasma was 10 cm in length, but future experiments require a source 1 m long. The RF source does not easily scale to the length. Consequently, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO 3 to form metal plasma. A 1 m long section of the drift tube inner surface of NTX will be covered with ceramic. A high voltage (˜1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. Plasma densities of 10 12 cm -3 and neutral pressures ˜10 -6 Torr are expected. A test stand to produce 20 cm long plasma is being constructed and will be tested before a 1 m long source is developed.

Enhanced energy coupling and x-ray emission in Z-pinch plasma implosions

NASA Astrophysics Data System (ADS)

Whitney, K. G.; Thornhill, J. W.; Apruzese, J. P.; Davis, J.; Deeney, C.; Coverdale, C. A.

2004-08-01

Recent experiments conducted on the Saturn pulsed-power generator at Sandia National Laboratories [R. B. Spielman et al., in Proceedings of the Second International Conference on Dense Z Pinches, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] have produced large amounts of x-ray output, which cannot be accounted for in conventional magnetohydrodynamic (MHD) calculations. In these experiments, the Saturn current had a rise time of ~180 ns in contrast to a rise time of ~60 ns in Saturn's earlier mode of operation. In both aluminum and tungsten wire-array Z-pinch implosions, 2-4 times more x-ray output was generated than could be supplied according to one-dimensional (1D) magnetohydrodynamic calculations by the combined action of the j×B acceleration forces and ohmic heating (as described by a classical Braginskii resistivity). In this paper, we reexamine the problem of coupling transmission line circuits to plasma fluid equations and derive expressions for the Z-pinch load circuit resistance and inductance that relate these quantities in a 1D analysis to the surface resistivity of the fluid, and to the magnetic field energy that is stored in the vacuum diode, respectively. Enhanced energy coupling in this analysis, therefore, comes from enhancements to the surface resistivity, and we show that plasma resistivities approximately three orders of magnitude larger than classical are needed in order to achieve energy inputs that are comparable to the Saturn experiment x-ray outputs. Large enhancements of the plasma resistivity increase the rate of magnetic field and current diffusion, significantly modify the qualitative features of the MHD, and raise important questions as to how the plasma fluid dynamics converts enhanced energy inputs into enhanced x-ray outputs. One-dimensional MHD calculations in which resistivity values are adjusted phenomenologically are used to illustrate how various dynamical assumptions influence the way enhanced energy inputs are channeled by the fluid dynamics. Variations in the parameters of the phenomenological model are made in order to determine how sensitively they influence the dynamics and the degree to which the calculated x-ray outputs can be made to replicate the kinds of large variations in the experimental x-ray power data that were observed in three nominally identical aluminum wire shots on Saturn.