Pub Date : 1994-06-06DOI: 10.1109/PLASMA.1994.589070
I. Pegel, L. D. Moreland, A. Roitman, E. Schamiloglu, V. Gubanov, A. Gunin, S. Korovin, V. Rostov, V. Tarakanov
In the SINUS family of pulsed, high current electron beam accelerators, the energy stored within a coaxial forming line (usually oil-insulated) is delivered to a load by means of a high voltage pressurized spark gap switch. For better matching to the load, a transmission line having a nonuniform wave impedance may be included between the switch and the load. Numerical simulation of the system described above has been performed with the use of 2.5D version of 2.5 and 3D, fully electromagnetic PIC-code KARAT. Geometrical parameters of several SINUS accelerators were used. Actual spatial configurations of the gas switch were considered, but the time dependence spark resistance between the electrodes was included as a variable. The obtained results are compared with actual pulse shapes from experiments. Conclusions are drawn about how the spark resistance as the function of time effects the pulse observed.
{"title":"Numerical Simulation And experimental Measurement Of pulse generation in coaxial Forming lines","authors":"I. Pegel, L. D. Moreland, A. Roitman, E. Schamiloglu, V. Gubanov, A. Gunin, S. Korovin, V. Rostov, V. Tarakanov","doi":"10.1109/PLASMA.1994.589070","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589070","url":null,"abstract":"In the SINUS family of pulsed, high current electron beam accelerators, the energy stored within a coaxial forming line (usually oil-insulated) is delivered to a load by means of a high voltage pressurized spark gap switch. For better matching to the load, a transmission line having a nonuniform wave impedance may be included between the switch and the load. Numerical simulation of the system described above has been performed with the use of 2.5D version of 2.5 and 3D, fully electromagnetic PIC-code KARAT. Geometrical parameters of several SINUS accelerators were used. Actual spatial configurations of the gas switch were considered, but the time dependence spark resistance between the electrodes was included as a variable. The obtained results are compared with actual pulse shapes from experiments. Conclusions are drawn about how the spark resistance as the function of time effects the pulse observed.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"9 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":"120958511","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.1994.588692
E.G. Zaiclrnan, K. Jensen
{"title":"Analytic Expressions for emmisions in Sharp Field emitters","authors":"E.G. Zaiclrnan, K. Jensen","doi":"10.1109/PLASMA.1994.588692","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588692","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"45 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":"122549374","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.1994.589120
K. Minami, K. Ogura, K. Kurashina, W. Kim, T. Watanabe
High-power microwave (HPM) sources based on electron cyclotron resonance (ECR) such as gyrotrons are fast wave devices and velocity component of electron beam perpendicular to guiding magnetic field is the origin of HPM. HPM sources based on Cherenkove mechanism are slow wave devices and can be driven by a beam without initial perpendicular velocity. The authors present here the experimental result that seems to be the first demonstration of high-power slow wave electron cyclotron maser (ECM) consisting of a large diameter sinusoidally corrugated metal waveguide driven by a beam with predominant parallel velocity. The designed size parameters of slow wave structure (SWS) are as follows: average radius 30 mm, corrugation pitch 3.4 mm, its amplitude h = 1.7 mm and total length 238 mm. They use an annular beam with radius 26.3 mm, energy 55 keV, current 200 A in their experiment. Expected Cherenkov oscillation frequency of TM01 mode is 20 GHz. The observed high-power microwaves can be quantitatively explained by a backward wave oscillation with Cherenkov mechanism enhanced by positive feedback of anomalous Doppler slow cyclotron wave. In conclusion, the slow wave ECM presented here will be a competitive candidate against gyrotrons for generating multi-MW millimeter microwaves available inmore » fusion plasma research.« less
{"title":"Experimental Demonstration Of A High-power Slow Wave Electron Cyclotron Maser Utilizing Corrugated Metal Structure","authors":"K. Minami, K. Ogura, K. Kurashina, W. Kim, T. Watanabe","doi":"10.1109/PLASMA.1994.589120","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589120","url":null,"abstract":"High-power microwave (HPM) sources based on electron cyclotron resonance (ECR) such as gyrotrons are fast wave devices and velocity component of electron beam perpendicular to guiding magnetic field is the origin of HPM. HPM sources based on Cherenkove mechanism are slow wave devices and can be driven by a beam without initial perpendicular velocity. The authors present here the experimental result that seems to be the first demonstration of high-power slow wave electron cyclotron maser (ECM) consisting of a large diameter sinusoidally corrugated metal waveguide driven by a beam with predominant parallel velocity. The designed size parameters of slow wave structure (SWS) are as follows: average radius 30 mm, corrugation pitch 3.4 mm, its amplitude h = 1.7 mm and total length 238 mm. They use an annular beam with radius 26.3 mm, energy 55 keV, current 200 A in their experiment. Expected Cherenkov oscillation frequency of TM01 mode is 20 GHz. The observed high-power microwaves can be quantitatively explained by a backward wave oscillation with Cherenkov mechanism enhanced by positive feedback of anomalous Doppler slow cyclotron wave. In conclusion, the slow wave ECM presented here will be a competitive candidate against gyrotrons for generating multi-MW millimeter microwaves available inmore » fusion plasma research.« less","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"137 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":"131455603","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.1994.589006
S. D. De Souza-Machado, J. Curry, F. Skiff
The density, temperature and flow speed of an argon plasma produced by an Asmussen cavity in a weak magnetic field is measured using Laser Induced Fluorescence and Langmuir probes. The sour is at one end of a main chamber that is in a magnetic mirror configuration, with pancake coils arranged at both the source end and the far end. The magnetic field at the source is below that required for ECR. The 2.45 GHz microwave resonant cavity has a diameter of 10.2 cm, with a 1.8 cm O.D. (1.35 cm I.D.) on-axis quartz tube within which the plasma is created, both of which are smaller than many of the Asmussen cavities described in the current literature.
{"title":"Plasma Production Using An Asmussen Cavity In A Magnetic Field","authors":"S. D. De Souza-Machado, J. Curry, F. Skiff","doi":"10.1109/PLASMA.1994.589006","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589006","url":null,"abstract":"The density, temperature and flow speed of an argon plasma produced by an Asmussen cavity in a weak magnetic field is measured using Laser Induced Fluorescence and Langmuir probes. The sour is at one end of a main chamber that is in a magnetic mirror configuration, with pancake coils arranged at both the source end and the far end. The magnetic field at the source is below that required for ECR. The 2.45 GHz microwave resonant cavity has a diameter of 10.2 cm, with a 1.8 cm O.D. (1.35 cm I.D.) on-axis quartz tube within which the plasma is created, both of which are smaller than many of the Asmussen cavities described in the current literature.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"73 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":"116530401","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.1994.588812
H. H. Kuehl, C.Y. Zhang
From numerical solutions of two colliding electromagnetic solitary waves, it is shown that their shapes are modified, and a trailing wake of plasma oscillations is produced by the collision. They therefore cannot be classified as solitons. For sufficiently large relative velocities, however, it is shown that the modifications to the vector and scalar potentials, as well as to the wake due to the collision, are small.
{"title":"Interaction Between Two Electromagnetic Solitary Waves in A Plasma","authors":"H. H. Kuehl, C.Y. Zhang","doi":"10.1109/PLASMA.1994.588812","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588812","url":null,"abstract":"From numerical solutions of two colliding electromagnetic solitary waves, it is shown that their shapes are modified, and a trailing wake of plasma oscillations is produced by the collision. They therefore cannot be classified as solitons. For sufficiently large relative velocities, however, it is shown that the modifications to the vector and scalar potentials, as well as to the wake due to the collision, are small.","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":"127671074","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.1994.588821
J. Soběhart
{"title":"Stability In Linear, Time-dependent, Fields","authors":"J. Soběhart","doi":"10.1109/PLASMA.1994.588821","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588821","url":null,"abstract":"","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"30 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":"132624060","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.1994.588775
J. Degnan, F. Lehr, D. Bell, A. Chesley, S. Coffey, S. Englert, T. Englert, D. Gale, J. Graham, C. Holmberg, T. Hussey, R. Lewis, C. Outten, R. Peterkin, D. Price, N. Roderick, E. Ruden, U. Shurnlak, G.A. Smith, P. Turchi
{"title":"Spherical Solid Liner Implosion Driven By 4.7 Megajoule Capacitor Discharge","authors":"J. Degnan, F. Lehr, D. Bell, A. Chesley, S. Coffey, S. Englert, T. Englert, D. Gale, J. Graham, C. Holmberg, T. Hussey, R. Lewis, C. Outten, R. Peterkin, D. Price, N. Roderick, E. Ruden, U. Shurnlak, G.A. Smith, P. Turchi","doi":"10.1109/PLASMA.1994.588775","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588775","url":null,"abstract":"","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":"133206851","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.1994.588780
H. Chen, B. Hilko, J. Chen, E. Panarella
play a n important roll in the later stages of implosion as the liner appears to break up into a stack of axially separated disks. It is suggested that this instability is excited by azimuthally symmetric striations in the solid bulk of the liner formed by int,eraction with the R-T “troughs” of the liquid phase. Such striations, interpreted as such, have been observed in meteors. Observed mode dominances are interpreted as resulting from electrical resistivity and visrosity. The validity of treating the solid phase as a highly viscous fluid subject to a c m wavelength R-T instability is discussed.
{"title":"1- And 2-D Numerical Simulations Of Spherical Pinches","authors":"H. Chen, B. Hilko, J. Chen, E. Panarella","doi":"10.1109/PLASMA.1994.588780","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.588780","url":null,"abstract":"play a n important roll in the later stages of implosion as the liner appears to break up into a stack of axially separated disks. It is suggested that this instability is excited by azimuthally symmetric striations in the solid bulk of the liner formed by int,eraction with the R-T “troughs” of the liquid phase. Such striations, interpreted as such, have been observed in meteors. Observed mode dominances are interpreted as resulting from electrical resistivity and visrosity. The validity of treating the solid phase as a highly viscous fluid subject to a c m wavelength R-T instability is discussed.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"109 32","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131912716","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.1994.589046
W. Manheimer, M. Lampe, G. Joyce, S. Slinker
Particle simulations of bulk discharges are constrained by the Debye length scale, which is orders of magnitude less than any other scale length of interest in the bulk plasma. While artificial scaling of the parameters, and nonuniform grid spacing can somewhat alleviate the problem, it still represents a serious constraint. Quasi-neutral fluid and hybrid simulations are routinely done; however in many plasmas on the kinetic nature of both the electrons and ions play important roles. The authors report progress on the development of a quasi-neutral particle simulation for an ECR discharge. The quasi-neutral nature of the plasma means that the algorithms for advancing the ions, electrons and for calculating the electric field are very non-standard. The ions are initially advanced in three dimensions. However very fast time scale, short scale length electrostatic electric fields impose average quasi-neutrality perpendicular to the field. The ion motion in the simulation is slightly corrected to reflect this. Along the field line, quasi-neutrality is maintained by very fast electron oscillations. The electron motion is also slightly corrected to insure quasi-neutrality. Once the particles are convected, the electric field is calculated from the electron momentum equation.
{"title":"Quasi-neutral Particle Simulations Of Magnetized Low Pressure Discharges,","authors":"W. Manheimer, M. Lampe, G. Joyce, S. Slinker","doi":"10.1109/PLASMA.1994.589046","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589046","url":null,"abstract":"Particle simulations of bulk discharges are constrained by the Debye length scale, which is orders of magnitude less than any other scale length of interest in the bulk plasma. While artificial scaling of the parameters, and nonuniform grid spacing can somewhat alleviate the problem, it still represents a serious constraint. Quasi-neutral fluid and hybrid simulations are routinely done; however in many plasmas on the kinetic nature of both the electrons and ions play important roles. The authors report progress on the development of a quasi-neutral particle simulation for an ECR discharge. The quasi-neutral nature of the plasma means that the algorithms for advancing the ions, electrons and for calculating the electric field are very non-standard. The ions are initially advanced in three dimensions. However very fast time scale, short scale length electrostatic electric fields impose average quasi-neutrality perpendicular to the field. The ion motion in the simulation is slightly corrected to reflect this. Along the field line, quasi-neutrality is maintained by very fast electron oscillations. The electron motion is also slightly corrected to insure quasi-neutrality. Once the particles are convected, the electric field is calculated from the electron momentum equation.","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"25 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":"133034934","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.1994.589083
H. Wu, A. McCurdy
It has been shown via quasilinear theory that a gyrotron oscillator with a highly dispersive waveguide structure can be mode locked by compensating with dispersion due to the electron beam. It is perhaps easier to modify the cavity geometry. A nonlinear investigation of mode locking is carried out using the MAGIC code. A closed, tapered cylindrical cavity gyrotron is used with an operating frequency of 20 GHz. A taper section of 11.25 cm with taper angle of 0.6{degree} is included. The cavity supports azimuthally symmetric TE{sub 01n} modes. The electron beam parameters are 50 kV beam voltage with 10 A beam current, and 0.5 cm guiding center radius. The external axial magnetic field is 7.46 kG. A beam velocity or beam density modulation is imposed on the input electrons to model the effect of a prebunching cavity. In the case of a 5%, 280 MHz density modulation the simulation results show the frequency interval between adjacent modes is almost identical to modulation frequency, indicating locking between adjacent modes. The output radiation consists of a train of narrow pulses (FFWHM {approximately}1 ns) at a 280 MHz repetition rate. An open-end tapered cavity connected to a waveguide is under investigation. Numerical simulationmore » results will be presented and an experimental design will be described.« less
{"title":"Study Of Mode Locking In Tapered Cavity Gyrotron Oscillators","authors":"H. Wu, A. McCurdy","doi":"10.1109/PLASMA.1994.589083","DOIUrl":"https://doi.org/10.1109/PLASMA.1994.589083","url":null,"abstract":"It has been shown via quasilinear theory that a gyrotron oscillator with a highly dispersive waveguide structure can be mode locked by compensating with dispersion due to the electron beam. It is perhaps easier to modify the cavity geometry. A nonlinear investigation of mode locking is carried out using the MAGIC code. A closed, tapered cylindrical cavity gyrotron is used with an operating frequency of 20 GHz. A taper section of 11.25 cm with taper angle of 0.6{degree} is included. The cavity supports azimuthally symmetric TE{sub 01n} modes. The electron beam parameters are 50 kV beam voltage with 10 A beam current, and 0.5 cm guiding center radius. The external axial magnetic field is 7.46 kG. A beam velocity or beam density modulation is imposed on the input electrons to model the effect of a prebunching cavity. In the case of a 5%, 280 MHz density modulation the simulation results show the frequency interval between adjacent modes is almost identical to modulation frequency, indicating locking between adjacent modes. The output radiation consists of a train of narrow pulses (FFWHM {approximately}1 ns) at a 280 MHz repetition rate. An open-end tapered cavity connected to a waveguide is under investigation. Numerical simulationmore » results will be presented and an experimental design will be described.« less","PeriodicalId":254741,"journal":{"name":"Proceedings of 1994 IEEE 21st International Conference on Plasma Sciences (ICOPS)","volume":"95 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":"133803955","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：