| Control of Current and Voltage Oscillations in a Short dc Discharge Making Use of External Auxiliary Electrode |
Jan 2012 |
5 pages |
| Authors:
A S Mustafaev; V I Demidov; I Kaganovich; S F Adams; M E Koepke; A Grabovskiy; WEST VIRGINIA UNIV MORGANTOWN
|
 | A dc discharge with a hot cathode is subject to current and voltage plasma oscillations, which have deleterious effects on its operation. The oscillations can be inhibited by installing an auxiliary electrode, placed outside of anode. By collecting a modest current through a small opening in anode, we show that the discharge becomes stable, in a certain pressure range. This method of avoiding current oscillations can be used, for example, ... |
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| Computer Simulations of Ion Transport Across Excitable Membrane Stimulated by External Field |
28 FEB 2006 |
11 pages |
| Authors:
CALIFORNIA UNIV LOS ANGELES DEPT OF PHYSICS
|
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| Investigations of an Environmentally Induced Long Duration Hall Thruster Start Transient (PREPRINT) |
06 FEB 2006 |
20 pages |
| Authors:
William A. Hargus; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A long duration Hall thruster start transient is produced by exposure of the thruster to ambient laboratory atmosphere. This behavior was first observed during operation of a cluster of four 200 W BHT-200 Hall effect thrusters where large anode discharge fluctuations, visible as increased anode current and a diffuse plume structure, occurred in an apparently random manner. During operation of a single thruster, the start transient appears as a quickly ... |
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| Millimeter Wave Plasma Interferometry in the Near Field of a Hall Plasma Accelerator (PREPRINT) |
27 JAN 2006 |
25 pages |
| Authors:
Mark A. Cappelli; Nicholas C. Gascon; William Hargus; STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
|
| Measurements are described of electron number density in the near field of a 200W Hall plasma accelerator using a 90 GHz microwave interferometer. The system is of a phase-bridge design, utilizing two signal arms from a fixed frequency source (one passing through the plasma) that recombine at two balanced mixers. A line-integrated electron density is obtained by comparing the in-phase and quadrature signals from the mixers. Measurements across chords through ... |
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| Nascap-2k Simulations of a VLF Plasma Antenna |
APR 2005 |
15 pages |
| Authors:
Myron J. Mandell; Victoria A. Davis; D. L. Cooke; A. T. Wheelock; Christopher J. Roth; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| The response of a plasma to very low frequency (VLF) (3 kHz to 20 kHz) antennas at orbital altitudes of 1000 to 10,000 kilometers has been a subject of scientific interest for many decades. As this antenna frequency is less than either the plasma frequency or the electron gyrofrequency, (both nearly 300kHz for a plasma density of 10(exp 9) cu cm and a magnetic field of 0.1 gauss), only certain ... |
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| A New Explanation of the Instability of High Intensity Discharge Operated in High Frequency |
07 APR 2004 |
2 pages |
| Authors:
Yang Z. Ming; Chai G. Sheng; Zhang Ming; BRIGHT STAR LIGHT AND ELECTRICITY IND CO LTD GUANG DONG (CHINA) R AND D CENTER FOR SPECIAL LIGHT SOURCES
|
| Analyzed the irrationality of so called "acoustic resonance" theory, that was suggested forty years ago to explain the instability of high frequency arc generated in high intensity discharge lamp. Presented a new idea that the ion oscillation in plasma is the culprit of instability of high frequency arc. |
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| Nonlinear Stage of Propagation of Wave Disturbances in the Topside Ionosphere |
11 JUN 2003 |
3 pages |
| Authors:
V. B. Ivanov; M. V ; IRKUTSK STATE UNIV (RUSSIA)
|
| This paper is continued investigations of propagation of disturbances of plasma concentration in the topside ionosphere. A mathematical modeling of the nonlinear stage of instability development has been carried out. It is shown that in the region of a maximum enhancement of perturbations, the relative fluctuations of plasma density can make up several tens of percent. |
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| Diagnostic Systems for Pulsed Electric Field Studies |
APR 2003 |
14 pages |
| Authors:
Karl H. Schoenbach; OLD DOMINION UNIV NORFOLK VA
|
| Experimental and modeling studies have shown that nanosecond electric fields allow us to affect internal structures of biological cells. Electrical diagnostics work with temporal resolution in the sub-nanosecond range is critical for evaluation of such ultrafast pulses for the extension of this new bioelectric technique from presently used electrode application in cell suspensions and tissues, to electromagnetic field interactions using antennas. Experiments are ongoing using the 4 GHz bandwidth oscilloscope ... |
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| Symposium H: 3-D Nanoengineered Assemblies |
DEC 2002 |
24 pages |
| Authors:
David P. Taylor; Koji Ikuta; Lhadi Merhari; Thomas Orlando; MATERIALS RESEARCH SOCIETY WARRENDALE PA
|
| The 3D Nanoengineered Assemblies symposium brought together researchers from a wide range of fields. 3D Nanoengineered Assemblies included much work that was "not quite truly 3D" and "not quite on the nanoscale." The result was a meeting in which common overarching themes emerged from presentations in widely separated research areas. More than 100 abstracts were submitted, and there were 29 invited talks covering work that spanned a remarkable number of ... |
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| Symposium H: Three-Dimensional Nanoengineered Assemblies |
DEC 2002 |
23 pages |
| Authors:
Koji Ikuta; Lhadi Merhari; Thomas Orlando; David P. Taylor; MATERIALS RESEARCH SOCIETY WARRENDALE PA
|
| The 3D Nanoengineered Assemblies symposium brought together researchers from a wide range of fields. The conference topic is not focused on a particular area of research, but on a goal that is being pursued by many groups approaching from diverse directions. 3D Nanoengineered Assemblies included much work that was "not quite truly 3D" and "not quite on the nanoscale." The result was a meeting in which common overarching themes emerged ... |
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| Ultracold Neutral Plasmas |
24 JUN 2002 |
6 pages |
| Authors:
T. C. Killian; M. J. Lim; S. Kulin; S. L. Rolston; NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD
|
| By photoionizing a sample of laser-cooled xenon atoms, we create ultracold neutral plasmas with initial temperatures of 1-1000 K and densities as high as l0(exp10)/cu cm. The plasma is formed by the trapping of electrons by the residual positive charge that is left after some electrons initially leave the sample. We excite plasma oscillations with applied radio frequency fields and use this to monitor the expansion of the unconfined plasma. ... |
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| Using the Plasma Noise Spectrum to Measure the Parallel Temperature in a Nonneutral Plasma |
24 JUN 2002 |
6 pages |
| Authors:
M. T. Nakata; Grant W. Hart; Bryan G. Peterson; BRIGHAM YOUNG UNIV PROVO UT DEPT OF PHYSICS AND ASTRONOMY
|
| A simple, non-destructive diagnostic for the temperature of a non-neutral plasma is desirable as plasma lifetimes increase and the confined species become more exotic. If the confinement system includes an isolated wall sector, the motion of the charges beneath that sector will result in a noise signal that can be directly related to the velocity distribution of the confined particles. Care must be taken to differentiate the resulting plasma signal ... |
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| The Air Force Clustered Hall Thruster Program |
13 JUN 2002 |
12 pages |
| Authors:
W. A. Hargus Jr; G. Reed; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| Preliminary results of the Air Force program investigating clustered Hall thrusters are presented, primarily experimental results on a cluster of four 200 W Busek BHT-200-X3 Hall thrusters. Preliminary measurements of plume current density, start transient interactions, cathode current sharing, and near exit plane magnetic fields are presented. Greatest thruster interaction occurs when cathodes are electrically connected. In a two thruster case, one cathode dominated electron emission, producing 90% of the ... |
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| Direct Observation of Feedout-Related Mass Oscillations in Plastic Targets |
01-Dec-2001 |
16 pages |
| Authors:
Y Aglitskiy; J H Gardner; A N Mostovych; S P Obenschain; A J Schmitt; C J Pawley; V Serlin; M Karasik; A L Velikovich; N Metzler; SCIENCE APPLICATIONS INTERNATIONAL CORP MCLEAN VA
|
| Feedout means the transfer of mass perturbations from the rear to the front surface of a driven target. When a planar shock wave breaks out at a rippled rear surface of the target, a lateral pressure gradient drives sonic waves in a rippled rarefaction wave propagating back to the front surface. This process redistributes mass in the volume of the target, forming the feedout-generated seed for ablative Rayleigh-Taylor (RT) instability. ... |
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| One-Dimensional Analysis of Hall Thruster Operating Modes |
AUG 2001 |
105 pages |
| Authors:
Eduardo Ahedo; Pablo Martinez; Juan M. Gallardo; UNIVERSIDAD POLITECNICA DE MADRID (SPAIN)
|
| The very simplicity of the Hall thruster structure with no screens or other control surfaces makes it difficult to understand the interrelationships which, in the end, localize and shape the various plasma regions existing in the accelerating channel. Since the radial magnetic field is usually shaped with a peak near the channel exit, the plasma structure has often been explained as simply a reflection of the magnetic field distribution. However, ... |
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| Experimental Investigations with a 5-kW-Class Laboratory Model Closed- Drifted Hall Thruster |
JAN 2001 |
272 pages |
| Authors:
Alec D. Gallimore; Brian E. Gilchrist; R. P. Drake; Frank S. Gulczinski; James M. Haas; MICHIGAN UNIV ANN ARBOR DEPT OF AEROSPACE ENGINEERING
|
| This final technical report summarizes research conducted at the Plasmadynamics and Electric Propulsion Laboratory (PEPL) to characterize the internal and plume plasma of a closed-drift Hall thruster (CDT). The project was composed of the following segments: 1) a 5-kW-class CDT (P5) was built and characterized in terms of performance and plume divergence; 2) the molecular- beam mass spectrometer (MBMS) was used to measure the ion energy distribution finction and charge ... |
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| 3-D Model Developments for Plasma Plumes |
18 DEC 2000 |
|
| Authors:
D. E. Hastings; M. Martinez-Sanchez; T. Onishi; D. L. Cooke; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | Two different studies were supported under this AASERT Grant, One, performed by Master's Candidate, Gregory Yashko, examined the technical feasibility and economic impact of clusters of micro-satellites propelled by micro-ion engines. It was concluded that sensor distribution among several satellites is appropriate when savings from the increased reliability outweigh the increased deployment costs, and that large constellations of g-satellites could feasibly perform missions currently being carried out by large satellites. ... |
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| A Conformal-Mapping Treatment of the Effect of a Semi-Infinite Gate on aTwo-Dimensional Electron Gas |
AUG 2000 |
19 pages |
| Authors:
Frank J. Crowne; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
|
| A pinched-off high-electron-mobility transistor containing a perfectly conducting two-dimensional electron gas (2DEG) is described mathematically within an idealized two-dimensional geometry, so that conformal mapping techniques can be used to compute internal fields at the transistor drain. The field and charge distribution at the drain end of the 2DEG calculated in this way suggest that the charge is a nonmonotonic function of position in this ... |
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| Charged Colloidal Structures in Plasmas |
09 JUL 2000 |
9 pages |
| Authors:
Sergey V. Vladimirov; Neil F. Cramer; SYDNEY UNIV (AUSTRALIA) SCHOOL OF PHYSICS
|
| Recent advances in the study of collective effects and particle motions in colloidal plasma crystals, ordered structures that form in the cathode sheath region of low temperature gaseous discharges, are presented. Plasma collective processes influence the arrangements and vibrations of colloidal "dust" particles in these Coulomb lattice structures. One important effect is the wake potential formation due to ion flow, leading to the vertical alignment of colloidal particles in experiments. ... |
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| An Investigation of Dusty Plasmas |
06 JUN 2000 |
197 pages |
| Authors:
Edward B. Tomme; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| This thesis constitutes a study of micron-sized particle behaviour in low-pressure radio frequency (RF) laboratory plasmas and of the plasma sheath in which these particles were suspended. A summary of the theoretical aspects of dust in a plasma includes reviews of the mechanisms behind the formation of the plasma sheath, development of a novel approach to the determination of the limiting RF amplitude at which the sheath ... |
|
| IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. The 26th IEEE International Conference on Plasma Science Held in Monterey, California, USA on June 20-24, 1999 |
24 JUN 1999 |
349 pages |
| Authors:
Deeney; LASERS AND ELECTRO-OPTICS SOCIETY (IEEE) PISCATAWAY NJ
|
| The ICOPS 1999 Conference was successfully held 20-24 June 1999 in Monterey, California. |
|
| Gigantic Oscillations of Dc-Voltage in Semiconductor Superlattices |
18 JUN 1999 |
2 pages |
| Authors:
Y. A. Romanov; J. Y. Romanova; RUSSIAN ACADEMY OF SCIENCES NIZHNY NOVGOROD INSTITUTE FOR PHYSICS OF MICROSTRUCTURES
|
| Electron properties of semiconductor superlattices (SL) in in high frequency intensive field (harmonic and biharmonic) were studied. We showed that the induced and self-induced transparency states of SL are unstable. Absolute negative conductance, unstable plasma oscillations and parametric amplificatoin of intense field harmonics destroy these states. As a result SL turns in a new state with dc-voltage and (or) non-linear plasma oscillations. The held-dependence of dc-voltage has hysteresis. The gigantic ... |
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| Parameter Space for Collisionless RF Sheaths |
08 APR 1999 |
18 pages |
| Authors:
Wallace M. Manheimer; NAVAL RESEARCH LAB WASHINGTON DC FUNDAMENTAL PLASMA PROCESSES
|
| As plasma processing reactors approach higher ion density, the sheath models which neglect the rf response of the ions become invalid. This work shows that at arbitrary ion density, the nature of the collisionless rf ion sheath can be described in a number of different regimes of parameter space. These regimes can all be visualized on a single two dimensional plot where the horizontal axis is the ion plasma frequency ... |
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| THz Radiation Source Through Periodically Modulated Structures |
16 JUN 1998 |
6 pages |
| Authors:
Erich Gornik; C. Rauch; G. Strasser; K. Unterrainer; W. Boxleitner; TECHNISCHE UNIV VIENNA (AUSTRIA) INST FUER FESTKOERPERELEKTRONIK
|
| We have concentrated our activities in the present period to demonstrate the generation of a plasmon instability which could lead to coherent plasmon oscillations in quantum well structures due to population inversion in the carrier distribution. Population inversion is needed to develop the plasma instability. We use a concept where the inversion is achieved by using an energetically selective extraction and injection of carriers into a confined active region consisting ... |
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| High Frequency Properties of Electron Waveguides, AC-Admittance, Scattering Parameters, Plasma Oscillations |
JUN 1998 |
4 pages |
| Authors:
Jan-Olof J. Wesstroem; ROYAL INST OF TECH STOCKHOLM (SWEDEN) DEPT OF ELECTRONICS
|
| The relation between the AC-admittance of single mode electron waveguides is discussed in terms of the more complete scattering matrix of the same structure. For low frequencies, the admittance coincides with the series-inductance expressions in the literature. For higher frequencies the admittance shows resonances where it vanishes due to standing plasma waves. |
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| THz Radiation Source Trough Periodically Modulated Structures |
04 DEC 97 |
7 pages |
| Authors:
Erich Gornik; C. Rauch; G. Strasser; K. Unterrainer; R. Kersting; TECHNISCHE UNIV VIENNA (AUSTRIA) INST FUER FESTKOERPERELEKTRONIK
|
| The work on the developement of new injection structures was continued. These experiments demonstrate the transition from coherent transport to band like scattering induced transport in a superlattice miniband. A mean free path of an injected electron in the order of 75 nm can be estimated for our ten period superlattices by using the experimental results for coherent and incoherent current at a fixed negative bias of 20 meV. This ... |
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| Quasineutral Particle Simulation of Magnetized Plasma Discharges: General Formalism and Application to ECR Discharges |
31 JUL 1997 |
52 pages |
| Authors:
Martin Lampe; Glenn Joyce; Wallace M. Manheimer; Steven P. Slinker; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
|
| In quasineutral plasmas it is difficult and inefficient to calculate the electrostatic field from Poisson's equation. We have developed a particle- in-cell/Monte Carlo (PIC/MC) simulation method for magnetized discharges, in which internal electric fields and sheath potentials are determined directly from the requirement of quasineutrality. Sheaths are treated as thin potential barriers, and the Bohm criterion for ion flux into the sheath is imposed as a boundary condition. Electron plasma ... |
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| Theoretical Investigation of Current Instabilities and Terahertz Oscillations in a Two-Dimensional Electron Fluid |
22 JUN 1997 |
12 pages |
| Authors:
M. I. Dyakonov; PHYSICAL-TECHNICAL INST ST PETERSBURG (RUSSIA)
|
| The purpose of this work is to develop further the theory of novel mechanisms for generation and detection of electromagnetic radiation in the terahertz range using the plasma oscillations of the two dimensional electron fluid in a Field Effect Transistor (FET). We have shown previously that the motion of electrons in a FET under certain conditions is described by hydrodynamic equations which coincide with those for shallow water, and that ... |
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| Electrostatic Particle-in-Cell Simulation Technique for Quasineutral Plasma |
31 MAR 97 |
38 pages |
| Authors:
Glenn Joyce; Martin Lampe; Steven P. Slinker; Wallace M. Manheimer; NAVAL RESEARCH LAB WASHINGTON DC SPACE PHYSICS SECTION
|
| We have developed a particle in cell simulation method in which the electrostatic field is determined from the requirement of quasineutrality, rather than Poisson's equation. Time steps may be orders of magnitude longer than the plasma period, and mesh cells orders of magnitude longer than the Debye length, since electron plasma oscillations do not appear in the model and the Debye length is essentially set to zero. The quasineutral approach ... |
|
| Discrete Vacuum Ultra Violet Reflective Interference Filter. |
18 FEB 1997 |
|
| Authors:
William R. Hunter; James P. Long; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A thin film reflecting interference filter (RIF) is designed to suppress unwanted harmonics thereby improving the monochromaticity of the radiation. An interference layer of material which has a well-defined plasma oscillation is deposited on a substrate and a mismatch layer is formed thereon. This interference layer exploits the interference between wavefronts reflected from the layer-substrate and the vacuum-layer interfaces to suppress higher order harmonics, while allowing good reflectance at the ... |
|
| Design and Development of a Plasma Wakefield Klystron |
23 DEC 96 |
34 pages |
| Authors:
John Pasour; David Smithe; Robert Seeley; Khanh Nguyen; MISSION RESEARCH CORP NEWINGTON VA
|
| This project investigated a novel microwave source that utilizes a plasma to bunch the electron beam. The electron beam interacts with the plasma via the wakefield produced by the head of the electron beam as it passes through the plasma. The resulting plasma oscillations bunch the beam at a frequency proportional to the plasma frequency. Thus, the device can be tuned by varying the plasma density. The theory of the ... |
|
| A Modified Beat Frequency Modulated Accretion Model I. Spin Periods and Magnetic Moments of Z-Sources Inferred from Horizontal Branch QPO |
96 |
35 pages |
| Authors:
Kent S. Wood; Peter F. Michelson; Mallory S. Roberts; STANFORD UNIV CA W W HANSEN LABS OF PHYSICS
|
| We present a modified beat-frequency modulated accretion model appropriate to a description of the horizontal branch oscillations of Z-type low-mass x-ray binaries. This model incorporates several new physical elements: (1) magnetic screening by the accretion disk and neutron star, (2) radiation pressure dominance in the inner disk, and (3) stellar rotation effects. Fitted to observational data, the model constrains the surface magnetic field in a typical LMXB Z source to ... |
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| Mathematical Modelling in Plasma Physics |
12 DEC 94 |
|
| Authors:
Natalia Sternberg; CLARK UNIV WORCESTER MA DEPT OF MATHEMATICS AND COMPUTER SCIENCE
|
| The investigator was able to give a complete mathematical analysis of a self-consistent dynamic model for rf sheaths in the frequency range between the ion and electron plasma frequencies for arbitrary collision parameters and arbitrary rf sheath voltages. Based on the above analysis, the investigator developed an algorithm which permits a complete numerical solution of the problem in its full generality without any restrictive assumptions. Using the developed algorithm, the ... |
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| Simultaneous Excitation of Parametric Decay Cascades and the OTSI in 1D Numerical Simulations Based on Zakarov's Equations |
MAR 94 |
3 pages |
| Authors:
R. A. Sprague; J. A. Fejer; NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
|
| This presentation describes results from numerical simulations based on Zakarov's equations. These results show, that for relatively low pump pressures, the OTSI is stabilized by the presence of the cascade and thus can coexist with the cascade. |
|
| Discrete Vacuum Ultra Violet Reflective Interference Filter. |
27 JUN 1993 |
|
| Authors:
William R. Hunter; James P. Long; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A thin film reflecting interference filter (RIF) is designed to suppress unwanted harmonics thereby improving the monochromaticity of the radiation. An interference layer of material which has a well-defined plasma oscillation is deposited on a substrate and a mismatch layer is formed thereon. This interference layer exploits the interference between wavefronts reflected from the layer-substrate and the vacuum-layer interfaces to suppress higher order harmonics, while allowing good reflectance at the ... |
|
| Analysis of the Dynamical Plasma Interactions with High-Voltage Spacecraft. |
JUN 1992 |
|
| Authors:
M. J. Mandell; T. Luu; J. Lilley; G. Jongeward; I. Katz; S-CUBED LA JOLLA CA
|
| This volume describes numerous plasma interaction problems done in support of DynaPAC code development, and in support of the SPEAR-II and SPEAR-3 programs. Two dimensional calculations show that oscillations of a beam emitted into an underdense plasma can cause overcharging of a beam emitting rocket, as was observed on MAIMIK. The effects of the sheath instability caused by orbital motion of a positive body are studied, showing that substantial potential ... |
|
| Low Energy Positron-Hydrogen Scattering |
JAN 88 |
25 pages |
| Authors:
M. D. Girardeau; OREGON UNIV EUGENE
|
| A new mechanism is proposed for atomic recombination in plasmas, whereby the binding energy is carried away by a plasmon. It is suggested that this mechanism may compete with radiative and three-body modes in the case of recombination to sufficiently highly-excited and perturbed states of hydrogen. A procedure for calculation of the transition rate is outlined in a model which treats the plasma oscillations by the Bohm-Pines canonical transformation and ... |
|
| China Report, Science & Technology |
30 APR 1987 |
95 pages |
| Authors:
JOINT PUBLICATIONS RESEARCH SERVICE ARLINGTON VA
|
| Partial Contents: NATIONAL DEVELOPMENTS - Reform of Local Science, Technology Commissions Discussed; Scientific Research Contracting System Examined; Wu Wushu Discusses New Scientific, Technical Legislation; Methods Sought To Link Research, Production More Effectively; APPLIED SCIENCES - Characteristics of Optogalvanic Spectrum in Discharge Plasma Oscillation; Experimental Study of Effect of Axial Magnetic Field in Free-Electron Lasers; ENVIRONMENTAL QUALITY - Environmental Protection Plans Detailed. |
|
| Waves and Electric Fields Associated with the December 27, 1984, Artificial Comet |
27 NOV 85 |
|
| Authors:
D. A. Gurnett; T. Z. Ma; R. R. Anderson; G. Haerendel; G. Paschmann; IOWA UNIV IOWA CITY DEPT OF PHYSICS AND ASTRONOMY
|
| A variety of plasma wave and electric field effects were observed during the AMPTE (Active Magnetospheric Particle Tracer Explorers) solar wind barium release. Electron plasma oscillations at the local electron plasma frequency provided measurements of the electron density during the entire event. A static electric field of about 1 to 2 mVolt/m was detected in the diamagnetic cavity. This electric field is in the same direction as the solar wind ... |
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| Effects of Finite Current Channel Width on the Current Convective Instability |
05 MAR 85 |
|
| Authors:
P. Satyanarayana; J. Chen; NAVAL RESEARCH LAB WASHINGTON DC
|
| The effects of the finite current channel width on the current convective instability are studied both analytically and numerically. First, using a sharp-boundary field-aligned current distribution which has a finite width along the plasma density gradient, the dispersion relation is obtained analytically. Numerical results are also presented for a diffuse-boundary current velocity distribution. Applications to the high latitude ionosphere are discussed. Key words include: Plasma instability, High latitude ionosphere, Fluid ... |
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| Neutral Beam Interactions with Materials |
JUN 1984 |
|
| Authors:
R. S. Ong; J. J. Duderstadt; R. M. Gilgenbach; MICHIGAN UNIV ANN ARBOR COLL OF ENGINEERING
|
| A duopigatron has been used to accelerate ion and neutral beams of hydrogen, argon krypton, and xenon. An important class of ion source plasma instabilities has been investigated. The frequency of source plasma oscillations scale as the square root of ion mass. Ion extraction efficiencies for the various mass species show excellent agreement with theory in the transition from the space charge imited regime to the ion saturation regime. Displaced ... |
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| Hysteresis in a Low-Pressure Argon Discharge. Revision |
SEP 1983 |
|
| Authors:
Robert L. Merlino; Steven L. Cartier; IOWA UNIV IOWA CITY DEPT OF PHYSICS AND ASTRONOMY
|
| Hysteresis in the discharge characteristics of a low pressure approx. (p = 10 to the minus 4th power Torr), magnetized argon plasma column is reported. The hysteresis is associated with sudden jumps in plasma density and discharge current as either the discharge voltage or magnetic field strength is varied. A substantial change in the plasma density profile and the appearance of coherent plasma oscillations are also observed. (Author) |
|
| Preliminary Report on UVDEP and PRODEP Results for the NRL (Naval Research Laboratory) Laser/HANE Experiment |
16 AUG 1983 |
|
| Authors:
E. Hyman; M. Mulbrandon; J. D. Huba; NAVAL RESEARCH LAB WASHINGTON DC
|
| We present predictions for the NRL laser/HANE experiment of the effects on an N2 background gas of (1) x-rays emitted following laser irradiation of an aluminum target, (2) debris ions moving out from the target, and (3) deposition of uv radiation resulting from interaction between the debris ions and the background gas. We calculate both primary ionization and time dependent chemistry changes. Results are based on two NRL codes, UVDEP ... |
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| Long Wavelength Limit of the E x B Instability |
17 JUN 1983 |
|
| Authors:
J. D. Huba; S. T. Zalesak; NAVAL RESEARCH LAB WASHINGTON DC
|
| We present an analytical expression for the growth rate of the E X B instability in the long wavelength limit, i.e., k sub y L sub n always less than 1, where k sub y is the wavenumber and L sub n is the scale length of the density gradient. Specifically, we obtain results for the case of a single discontinuity in plasma density. (Author) |
|
| Strong Coupling Effects on Bound States in Plasmas |
MAR 1983 |
|
| Authors:
Gabor J. Kalman; BOSTON COLL CHESTNUT HILL MA
|
| Further progress in the areas of (1) kinetics and response of strongly coupled multi-component plasmas, (2) study of plasma phase transition and determination of the degree of ionization of a dense plasma, and (3) generalization of the Thomas-Fermi-Debye-Huckel scheme for strongly coupled plasmas with atoms and ions, is reported: A multi-species formalism has been worked out. Details of the phase transition and of the critical curve have been found. Relationship ... |
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| Kinetic Theory of Gases, Magneto-Fluid Dynamics and Their Application |
JAN 1983 |
|
| Authors:
H. Grad; NEW YORK UNIV NY COURANT INST OF MATHEMATICAL SCIENCES
|
| This paper describes research results and cites progress resulting from work performed during this period of the grant. The areas covered in this report are (1) mathematical theory of turbulent fluctuations of a plasma near thermal equilibrium, (2) the theory of non-linear thermal and diffusive waves in finite mass and reacting media, (3) the development of algorithms for the Helmholtz equation, (4) progress in the development of theory for Queer ... |
|
| High-Latitude and Equatorial Research Support for Predicting High- Altitude Nuclear Effects |
01 AUG 1982 |
|
| Authors:
Charles L. Rino; James F. Vickrey; Robert C. Livingston; Roland T. Tsunoda; SRI INTERNATIONAL MENLO PARK CA
|
| This report summarizes the high-latitude and the equatorial natural ionospheric research support that has been conducted to improve and extend high- altitude nuclear predictive capability. This work marks the formal completion of the equatorial research effort. That effort has been very successful and the results are summarized in detail. The primary future effort will be directed toward auroral phenomena. The preliminary work in this area is described in the report. ... |
|
| Strong Coupling Effects on Bound States in Plasmas |
AUG 1982 |
|
| Authors:
Gabor J. Kalman; BOSTON COLL CHESTNUT HILL MA
|
| Progress in three major areas is reported: (1) Kinetics and response of strongly coupled multi-component plasmas. (2) Study of plasma phase transition and determination of the degree of ionization of a dense plasma (3) Generalization of the Thomas-Fermi-Debye-Huckel scheme for strongly coupled plasmas with atoms and ions. (Author) |
|
| A Dynamic Model for the Auroral Field Line Plasma in the Presence of Field-Aligned Current |
23 JUL 1982 |
|
| Authors:
H. G. Mitchell Jr.; P. J. Palmadesso; NAVAL RESEARCH LAB WASHINGTON DC
|
| We have developed a dynamic numerical model of the plasma along an auroral field line in order to provide a vehicle for studying ionosphere- magnetosphere coupling processes. The model is a multi-moment multi-fluid approximation of a gyrotropic plasma consisting of three species (electrons, hydrogen ions, oxygen ions) along a segment of auroral magnetic field line extending from an altitude of 800 km to 18 earth radii. We have performed preliminary ... |
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| Cold Waveguide Electrostatic Modes between Upper Hybrid and Plasma Resonance |
JUL 1982 |
|
| Authors:
G. J. Morales; J. E. Maggs; CALIFORNIA UNIV LOS ANGELES DEPT OF PHYSICS
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| The structure of electrostatic oscillations is determined for a cold plasma with a zero order density gradient along the magnetic field. A set of well-behaved structures, bounded at plasma resonance, exists for discrete values of perpendicular wavenumber. Under these conditions the plasma acts as a waveguide. A Green's function suitable for sources located in the overdense region of the plasma is constructed from these waveguide-like solutions. (Author) |
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Reports by Keyword(s)
PLASMA OSCILLATION
