Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589112
M. Fazio, W. B. Haynes, B. Carlsten, R.M. Stingfield
This paper describes the experimental development of a long pulse high current, annular beam relativistic klystron amplifier. The desired performance parameters are 1 GW output power and 1 {mu}s pulse length with an operating frequency of 1.3 GHz. the electron beam voltage and current are nominally 600 kV and 5 kA. Peak powers approaching 500 MW have been achieved in pulses of 1 {mu}s nominal baseline-to-baseline duration. The half power pulse width is 0.5 {mu}s. These pulses contain an energy of about 160 J. The rf output terminates abruptly just before the highest parts of the beam voltage and current pulses are reached. The cause of the premature termination of the rf pulse has not been definitely determined. Experimental observations indicate that the rf pulse termination could be the result of the output cavity gap voltage being too high, causing electron reflection at the gap and rf breakdown across the gap. To reduce the output gap voltage, a new output cavity has been designed with a much lower shunt impedance and a loaded Q of 4. Current experimental results and theoretical design considerations for this class of tube are discussed.
{"title":"One microsecond Pulse-width Annular Beam Relativistic Klystron Operating at 500 MW","authors":"M. Fazio, W. B. Haynes, B. Carlsten, R.M. Stingfield","doi":"10.1109/PLASMA.1994.589112","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589112","url":null,"abstract":"This paper describes the experimental development of a long pulse high current, annular beam relativistic klystron amplifier. The desired performance parameters are 1 GW output power and 1 {mu}s pulse length with an operating frequency of 1.3 GHz. the electron beam voltage and current are nominally 600 kV and 5 kA. Peak powers approaching 500 MW have been achieved in pulses of 1 {mu}s nominal baseline-to-baseline duration. The half power pulse width is 0.5 {mu}s. These pulses contain an energy of about 160 J. The rf output terminates abruptly just before the highest parts of the beam voltage and current pulses are reached. The cause of the premature termination of the rf pulse has not been definitely determined. Experimental observations indicate that the rf pulse termination could be the result of the output cavity gap voltage being too high, causing electron reflection at the gap and rf breakdown across the gap. To reduce the output gap voltage, a new output cavity has been designed with a much lower shunt impedance and a loaded Q of 4. Current experimental results and theoretical design considerations for this class of tube are discussed.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"53 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":"124628217","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.588747
M. E. Light, F.F. Chen
{"title":"Wave Excitation With Helical Antennas","authors":"M. E. Light, F.F. Chen","doi":"10.1109/PLASMA.1994.588747","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588747","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"43 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":"125909666","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589001
R. Kares
{"title":"The Role Of Potential Hills And Reflexing Electrons In The Operation Of A Plasma Opening Switch","authors":"R. Kares","doi":"10.1109/PLASMA.1994.589001","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589001","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"28 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":"127267292","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589048
K. Riemann
{"title":"Theory Of The Plasma-sheath Transition And The Bohm Criterion","authors":"K. Riemann","doi":"10.1109/PLASMA.1994.589048","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589048","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"42 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":"126763010","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.588757
J. Nilsson, J.F. Eninger
An Advanced Ionizer for Atmospheric Plasma Mark Rader and Igor Alexeff University of Tennessee The production of ions by corona in air has been improved by a factor of 10 without either increasing the voltage or reducing the electrode gap spacing. This improvement has been accomplished by noting that the corona process occurs in a very limited spatial region around the corona points or wires. By replacing the air in this limited region by a feed of nonelectronegative gas such as argon, nitrogen, or helium, the local production of ions is greatly enhanced. Once these ions flow into the surrounding air, they cannot recombine unless they find ions of the opposite charge. Thus the ions flow freely across large air gaps. A n . additional advantage of the local gas feed system is that the ionization occurs locally, and processes in the surrounding air that produce sparkover do not occur. The use of these improved ionizers in electrostatic precipitators should result in enhanced pollution removal, and a patent is pending.
大气等离子体的先进电离器田纳西大学Mark Rader和Igor Alexeff在不增加电压或减少电极间隙的情况下，空气中电晕离子的产生已经提高了10倍。这种改进是通过注意到日冕过程发生在日冕点或导线周围非常有限的空间区域来实现的。用非电负性气体(如氩气、氮气或氦气)替代这一有限区域内的空气，大大增强了局部离子的产生。一旦这些离子流入周围的空气中，它们就不能再结合，除非它们找到带相反电荷的离子。这样离子就可以自由地流过大的气隙。A n .;局部气体供给系统的另一个优点是电离发生在局部，并且不会发生在周围空气中产生火花的过程。在静电除尘器中使用这些改进的电离器应该会导致增强的污染去除，专利正在申请中。
{"title":"Numerical Modelling Of Ozone Production In A Pulsed Homogeneous Oxygen Discharge","authors":"J. Nilsson, J.F. Eninger","doi":"10.1109/PLASMA.1994.588757","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588757","url":null,"abstract":"An Advanced Ionizer for Atmospheric Plasma Mark Rader and Igor Alexeff University of Tennessee The production of ions by corona in air has been improved by a factor of 10 without either increasing the voltage or reducing the electrode gap spacing. This improvement has been accomplished by noting that the corona process occurs in a very limited spatial region around the corona points or wires. By replacing the air in this limited region by a feed of nonelectronegative gas such as argon, nitrogen, or helium, the local production of ions is greatly enhanced. Once these ions flow into the surrounding air, they cannot recombine unless they find ions of the opposite charge. Thus the ions flow freely across large air gaps. A n . additional advantage of the local gas feed system is that the ionization occurs locally, and processes in the surrounding air that produce sparkover do not occur. The use of these improved ionizers in electrostatic precipitators should result in enhanced pollution removal, and a patent is pending.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"177 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":"122906059","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.588913
W. Zhang, C. Xiao, L. Zhang, A. Hirose
Liniiter biasiiig experiments has been carried out on the STOR-51 tokaiiiak. The liiniter consists of eight stainless steel scgiiieiits in a sandwich structure with equal number of segments on hotli sides of a ceramic base. In the experiments reported here, all four segments on one side are connected togct1ic.r to form a limiter and can be biased either positively (1120 lr, 25 A) or nega.tively (-380 V, -40 A) with respect to tlie tokamak chamber. The segments on the other side are used to measure the plasma floating potential and its fluctuations ( V J ) in the scrape-off-layer (SOL). A movable Langmuir probe at the outer board measures those quantities in both SOL and at the edge (./a < 1) regions. It has been found that floating potential fluctuations in the SOL region depend mainly on the polarity of the limiter potential, not the potential gradient. The potential fluctuations in the SOL were strongly suppressed with a positive limiter potential and enhanced dramatically with a negative limiter potential, despite observations that the potential profile was steeper in the SOL region during negative biasing. The behaviour of Vf may be related to the interchange-flute instability with dissipation caused by fluctuating currents flowing through the Langmuir sheath potential near the surface of the limiter'. At the plasma edge the suppression of the fluctuations is always accompanied by a steeper potential profile, which indicates that the rotational shear layer may be the cause for fluctuation suppression inthat region. Despite different behaviours of Vf during the positive and negative bias, improved confinement has been observed for both bias polarities. The improved confinement is characterized by significant density increase (100% for positive bias and 80% for negative bias) and sudden drop in H, radiation level.
{"title":"Limiter Biasing Experiments On The Stor-m Tokamak","authors":"W. Zhang, C. Xiao, L. Zhang, A. Hirose","doi":"10.1109/PLASMA.1994.588913","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588913","url":null,"abstract":"Liniiter biasiiig experiments has been carried out on the STOR-51 tokaiiiak. The liiniter consists of eight stainless steel scgiiieiits in a sandwich structure with equal number of segments on hotli sides of a ceramic base. In the experiments reported here, all four segments on one side are connected togct1ic.r to form a limiter and can be biased either positively (1120 lr, 25 A) or nega.tively (-380 V, -40 A) with respect to tlie tokamak chamber. The segments on the other side are used to measure the plasma floating potential and its fluctuations ( V J ) in the scrape-off-layer (SOL). A movable Langmuir probe at the outer board measures those quantities in both SOL and at the edge (./a < 1) regions. It has been found that floating potential fluctuations in the SOL region depend mainly on the polarity of the limiter potential, not the potential gradient. The potential fluctuations in the SOL were strongly suppressed with a positive limiter potential and enhanced dramatically with a negative limiter potential, despite observations that the potential profile was steeper in the SOL region during negative biasing. The behaviour of Vf may be related to the interchange-flute instability with dissipation caused by fluctuating currents flowing through the Langmuir sheath potential near the surface of the limiter'. At the plasma edge the suppression of the fluctuations is always accompanied by a steeper potential profile, which indicates that the rotational shear layer may be the cause for fluctuation suppression inthat region. Despite different behaviours of Vf during the positive and negative bias, improved confinement has been observed for both bias polarities. The improved confinement is characterized by significant density increase (100% for positive bias and 80% for negative bias) and sudden drop in H, radiation level.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"251 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":"132677733","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589052
E. Meeks, M. Cappelli
{"title":"The Electrical Boundary Layer And Current Transfer Between A Thermal Plasma And A Plane Electrode","authors":"E. Meeks, M. Cappelli","doi":"10.1109/PLASMA.1994.589052","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589052","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"12 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":"123912857","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589053
P. Stout, M. Kushner
The advantages of high power photoconductive semiconductor switches (PCSS) such as high hold-off voltage and fast rise times have motivated significant development efforts. However, observations of lock-on, non-uniformities in the electric field, and filamentation of current flow across the device when switching at high fields have raised concerns about the scaling of PCSS to higher currents. To investigate these issues, a two dimensional time dependent computer model of GaAs PCSS has been developed with the motivation of understanding filament formation. The model solves the continuity equations for electrons and holes, conservation equations for trapping sites, the energy equation for the lattice. Poisson`s equation, and a circuit equation. Physical effects in the model include band-to-band impact ionization, trap impact ionization, photoionization, and negative differential resistance. The physical devices investigated with the model are based on the Bulk Optical Semiconductor Switch (BOSS) developed by Schoenbach. In this talk a description of the model will be presented followed by consequences of switch geometries, gain mechanisms, and non-uniform injection and illumination on the operation of the device.
{"title":"Two Dimensional Time Dependent Modeling Of Optically Switched GaAs","authors":"P. Stout, M. Kushner","doi":"10.1109/PLASMA.1994.589053","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589053","url":null,"abstract":"The advantages of high power photoconductive semiconductor switches (PCSS) such as high hold-off voltage and fast rise times have motivated significant development efforts. However, observations of lock-on, non-uniformities in the electric field, and filamentation of current flow across the device when switching at high fields have raised concerns about the scaling of PCSS to higher currents. To investigate these issues, a two dimensional time dependent computer model of GaAs PCSS has been developed with the motivation of understanding filament formation. The model solves the continuity equations for electrons and holes, conservation equations for trapping sites, the energy equation for the lattice. Poisson`s equation, and a circuit equation. Physical effects in the model include band-to-band impact ionization, trap impact ionization, photoionization, and negative differential resistance. The physical devices investigated with the model are based on the Bulk Optical Semiconductor Switch (BOSS) developed by Schoenbach. In this talk a description of the model will be presented followed by consequences of switch geometries, gain mechanisms, and non-uniform injection and illumination on the operation of the device.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"6 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":"128930248","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589076
R. Kares, V. Thomas, M.E. Jones
The fully three dimensional electromagnetic curvilinear PIC code ISIS is used on the CM5 supercomputer to simulate the operation of the Large Orbit Gyrotron (LOG) high power microwave source which is current under development at Los Alamos. This source consists of a vane resonator magnetron-type geometry with a rotating annular electron beam in a cusp magnetic field and represents a formidable intrinsically three dimensional computational problem. Animations of beam dynamics and microwave generation in the device will be presented. Comparison with results from the LANL LOG experiment will also be discussed.
{"title":"Three Dimensional Simulations Of The Lanl Large Orbit Gyrotron Using Isis On The Connection Machine","authors":"R. Kares, V. Thomas, M.E. Jones","doi":"10.1109/PLASMA.1994.589076","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589076","url":null,"abstract":"The fully three dimensional electromagnetic curvilinear PIC code ISIS is used on the CM5 supercomputer to simulate the operation of the Large Orbit Gyrotron (LOG) high power microwave source which is current under development at Los Alamos. This source consists of a vane resonator magnetron-type geometry with a rotating annular electron beam in a cusp magnetic field and represents a formidable intrinsically three dimensional computational problem. Animations of beam dynamics and microwave generation in the device will be presented. Comparison with results from the LANL LOG experiment will also be discussed.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"42 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":"128413507","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}
Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.588985
J. Booske, L. Zhan, R. Cooper, J. Shohet, K. Shenai, D. Dallman, M.J. Goeckner, R. Breun, W. Hitchon, E. Wickesberg, R. Speth, J. Jacobs, G. Was
{"title":"Buried Ceramic Layer Formation In Glass And Silicon Using Plasma Source Ion Implantation","authors":"J. Booske, L. Zhan, R. Cooper, J. Shohet, K. Shenai, D. Dallman, M.J. Goeckner, R. Breun, W. Hitchon, E. Wickesberg, R. Speth, J. Jacobs, G. Was","doi":"10.1109/PLASMA.1994.588985","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588985","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"18 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":"116011070","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}
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