Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)最新文献

{"title":"Git8 Long Conduction PCS Operation At 5ma Current Level","authors":"A. Kim, B.M. Kovalohuk, V. Kokshenev, S. Loginov","doi":"10.1109/PLASMA.1994.589003","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589003","url":null,"abstract":"The long conduction POS technology is studied on GIT8 since 1992. The usual type POS with radial plasma injection has demonstrated slow opening into small impedance load simulating z-pinch load conditions. Also in this POS large amount of plasma was pushed by EM force into load region located about 60 cm downstream during 1.3 {mu}s conduction time. To avoid these problems a new POS design was developed called PSIPS (Plasma Switch with Inertial Plasma Stopping). The first PSIPS version was studied on GIT4. The idea is to inject plasma with high initial velocity between coaxial electrodes in direction opposite to that of the EM force. In this case part of the conduction time plasma moves along from the load, then stops and changes the direction of its movement to the opposite one. As a result the total time until plasma is removed from the switch region increases without increasing plasma mass and/or cathode diameter. The PSIPS operation at 40 kV charging voltage on GIT8 has demonstrated improved opening into small impedance load compared to the usual POS with radial injection. With cathode diameter of 160 mm it opens at 2.6 MA peak conduction current at a charge time of 1.3more » {mu}s.« less","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131727797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inductively-loaded Extended Gaps For Relativistic Klystrons","authors":"M. Lampe, R. Hubbard, M. Friedman, V. Serlin","doi":"10.1109/PLASMA.1994.589114","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589114","url":null,"abstract":"As the power and the frequency of a relativistic klystron increase, design of both modulation and extraction cavities becomes increasingly difficult. If the gap is narrow, the rf electric field begins to exceed breakdown limits. On the other hand, if the gap width exceeds a small fraction of a wavelength, typical extraction modes do not couple well, and space charge potential energy reduces efficiency and limits the current that can cross the gap. The authors present theoretical investigations, numerical simulations, and initial experimental results on a novel gap design which incorporates an inductively-loaded return-current structure. The structure consists of a series of washers (e.g., 25 in the device which has been built), mounted on a small number (e.g., four) of longitudinal conducting posts which bridge the gap. The unmodulated component of the beam current induces a return current which flows freely in the posts; as a result, the beam`s unmodulated space charge is nearly completely neutralized. The washers serve to increase the capacitive coupling between the beam and the structure, and to provide azimuthal symmetry for the charge on the structure. However, the inductance of the posts is sufficient to inhibit rf return current, and thus the structure sustains themore » longitudinal rf field in the cavity. With appropriate choice of resonant modes, it appears that gap widths exceeding a half wavelength can be used for modulation of high-current beams, as well as extraction of rf energy with high efficiency.« less","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126413634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coaxial Plasma Thruster With Applied Magnetic Nozzle Fields","authors":"R. Hoyt, J. Scheuer, K. Schoenberg, R. Gerwin, R. Moses, I. Henins","doi":"10.1109/PLASMA.1994.588903","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588903","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115473493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasma Physics In Latin America","authors":"A. Rodrigo","doi":"10.1109/PLASMA.1994.588860","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588860","url":null,"abstract":"The status of plasma physics in Latin America is reviewed. The review surveys the history and present situation of the regional activities in high-temperature plasma research, plasma astrophysics, and technological applications of plasma physics. In particular, it presents data on the trends of evolution of scientific staff, annual operating budget, and publication rate for the major Latin American plasma groups during the decade 1983-1992. On this basis, the prospects for further growth and the potential for regional contribution to the mainstream of international plasma research and development are discussed. >","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115593961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equilibrium Of Intergalactic Currents In The Plasma Universe","authors":"B. E. Meierovich","doi":"10.1109/PLASMA.1994.588730","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588730","url":null,"abstract":"The plasma universe approach to the structure of the universe considers space to be filled with a network of currents which can undergo pinch compression. The equilibrium structures of such currents are treated in the same way as the structure of laboratory pinches. The difference, for the galactic case, is that gravitational interaction forces between the particles must be included into the analysis. Straightforward calculation shows that in equilibrium the energy of magnetic compression and gravitational compression must be exactly compensated by the energy of electrostatic repultion and kinetic energies of the charges. If gravitational energy is much smaller than the magnetic energy, we get balance of energies for relativistic pinch systems. In nonrelativistic limit the balance is reduced to the well known Bennet relation.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124205070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Portable Parallel Code For Plasma Simulations: Development Experience And Initial Results","authors":"P. Liewer, J. Brackbill, S.R. Karmesin","doi":"10.1109/PLASMA.1994.589034","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589034","url":null,"abstract":"Plasma physics covers a wide variety of phenomena that are beyond the reach of symbolic mathematics, and for which experiments are often difficult. It is necessary to rely on computer experiments to test theories and understand the data. The authors describe progress in constructing a portable parallel Particle in Cell (PIC) code for three dimensional plasma simulations, and initial physics results using it for the Global Heliosphere problem. The code is designed to scale well to large parallel machines to take advantage of the fastest computers that are likely to be found in the foreseeable future. It is designed to allow the user to do a straight fluid (MHD) simulation, a kinetic PIC simulation to sample the velocity-space behavior of a system or a FLIP PIC simulation to model a low dissipation continuum fluid. It is designed to allow as much as possible of the algorithm to be written in dimension-independent style to allow the code to be used in 1, 2 or 3 dimensional systems. It is designed to be able to handle moderately complex geometries efficiently through the use of multiple patches, each of which is a deformable logically cartesian mesh. It is designed for several types ofmore » portability: to different numerics, physics, architectures, and people.« less","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124582988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Collisional Plasmas: Monte Carlo Calculations Without Samplinq Errors","authors":"D. Lemons, M.E. Jones","doi":"10.1109/PLASMA.1994.588681","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588681","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114591462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studies Of A Pre-bunched Backward Wave Oscillator","authors":"C. Alexander, D. Shiffler","doi":"10.1109/PLASMA.1994.589069","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589069","url":null,"abstract":"Among various high-power microwave sources, multiwave Cerenkov Generators (MWCGs) developed by Bugaev et al., High Current E1ec:tronics Institute, Russia, have attained top data of output. Radiation powers 3 GW at wave length 9.7 mm and efficiency 20 % were reported. Here a large mean diameter D of the slow wave structure (SWS) is the key point. Although the physical processes involved in the MWCGs are complicated, we here design a large diameter backward wave oscillator (LDBWO) operating at 24 GHz high-power microwaves without decreasing D. The inner radius of the metal surface of the SWS is assumed to vary sinusoidally as R(z)=R0+hcos(2Xz/z ) . The oscillation frequency is raised by cfloosing carefully small values of z o and h. Numerical study is made within the scope of linear pinch point analysis [1 1 for a SWS available in 24 GHz LD-BWO. Especially, we find that there exists a starting energy in addition to starting current in electron beam for initiating microwave oscillation, if the finite length L of SWS is taken into account. The optimized size parameters of SWS are as follows: RO=30 mm, h=1.7 mm, zo=3.4 mm, L=70z -238 mm and annular beam radius R -26.7 mm. !$he beam energy V -65-100 keV an$the beam current Ib up to P-kA are assumed. For Vb=65 keV, I m ( a ) C O , no matter how large Ib would be. No oscillations can be expected. The starting energy is found to be 76.5 keV and it is a decreasing function of L. It must be noted that the starting energy is not the sufficient condition, but the necessary condition for starting oscillation. Additional condition is that the radiation must grow up against the leakage at the both ends. This condition gives the starting current that is increasing function of the leakage. Intensity of output radiation from the designed LD-BWO is expected to be weak, because of small h. However, the output can be drastically enhanced, in the case that the coupling of the radiation with anomalous Doppler electron cyclotron resonance exists. Our exper ment for high-power, high-efficiency oscil ation is presented elsewhere. 5Pll","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116167032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulations And Measurements Of Alumina Particles In Plasma Spraying","authors":"W. H. Zhuang, H.F. Chen, K. Etemadi, D. Benenson","doi":"10.1109/PLASMA.1994.588982","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588982","url":null,"abstract":"A plasma spraying torch (Miller SG-100) has been studied by numerical modeling and Laser Doppler Velocimetry (LDV) techniques. Results are presented for axisymmetric turbulent argon plasma jets flowing into a cold air environment with the injection of alumina particles. The mathematical model involves the simultaneous solution of the continuity, momentum and energy equations for the plasma jet, and the dynamics and heat transfer of the particles in the plasma. Calculations are performed using the both parabolic and elliptic approaches. Turbulent effects are represented by the k-E model. The turbulent dispersion effect on the particles is also included. Coupling between the plasma jet and the particles is considered. -At a current of 900 A, plasma temperatures determined by modeling are compared with experimental results [l]. The difference is less than 4% at a distance less than 2 cm from the nozzle exit. At longer distance, plasma temperatures, obtained from modeling are about 3040% higher than those measured in [I] . At a current of 300 A, particle velocities obtained by the simulation are compared to LDV measurements with single and double injection. At a distance of 5.2 cm from the torch nozzle exit, particle velocities show a peak off-axis profile as measured by L,DV and as calculated by numerical modeling. Particle velocities determined from modeling are 20% higher than those measured by LDV at the axis. Differences between particle velocities determined from the parabolic and elliptic approaches are within 5%.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116343574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parametric Studies Of Electron-energy -distribution-function And Rate Constants For Plasma-etching Reactors","authors":"J. Shon, E. Meeks, R. Kee","doi":"10.1109/PLASMA.1994.588746","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588746","url":null,"abstract":"The resulting reaction-rate coefficients are used to generate standard Arrhenius fits for the rate constants as a function of average electron energy. These reaction-rate coefficients are then employed in a plasma reactor model through a Chemkin interface. Results from the reactor model indicate the dependence of ion, electron, and neutral species concentrations on the assumptions inherent in the reactionrate determinations. We present differences between results","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"898 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116391522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}