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Particle simulation of the kinetic Kelvin–Helmholtz instability in a magnetoplasma 磁等离子体中动力学开尔文-亥姆霍兹不稳定性的粒子模拟
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860826
DongSheng Cai, L. Storey, T. Itoh
{"title":"Particle simulation of the kinetic Kelvin–Helmholtz instability in a magnetoplasma","authors":"DongSheng Cai, L. Storey, T. Itoh","doi":"10.1063/1.860826","DOIUrl":"https://doi.org/10.1063/1.860826","url":null,"abstract":"The kinetic Kelvin–Helmholtz instability in a collisionless magnetoplasma is simulated numerically in cases where the ion gyroradius is comparable with or larger than the spatial scale of the cross‐field shear. The approach consists of starting the simulation from a state close to equilibrium, then observing the linear growth of instabilities and their ultimate saturation. The initial quasiequilibrium state is set up by a newly developed particle loading method; the instabilities are excited by numerical noise. The simulation is performed in two dimensions, in the plane perpendicular to the magnetic field, using an electrostatic particle code. The results for the kinetic Kelvin–Helmholtz instability are similar to those predicted by a hydromagnetic model, except that they depend slightly on the sign of the shear. Other instabilities are observed also: when the ion gyroradius is small on the scale of the shear, there is an unidentified short‐wavelength instability characterized by k Δx≥1, where k is the wa...","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124929999","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}
引用次数: 10
Three‐dimensional fluid simulations of the nonlinear drift‐resistive ballooning modes in tokamak edge plasmas 托卡马克边缘等离子体非线性漂阻气胀模式的三维流体模拟
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860842
P. Guzdar, J. Drake, D. McCarthy, A. Hassam, C. Liu
{"title":"Three‐dimensional fluid simulations of the nonlinear drift‐resistive ballooning modes in tokamak edge plasmas","authors":"P. Guzdar, J. Drake, D. McCarthy, A. Hassam, C. Liu","doi":"10.1063/1.860842","DOIUrl":"https://doi.org/10.1063/1.860842","url":null,"abstract":"A three‐dimensional study of the turbulence and sheared flow generated by the drift‐resistive ballooning modes in tokamak edge plasmas has been completed. The fluid simulations show that 10%–15% percent density fluctuations can develop in the nonlinear state when the self‐consistently generated shear flow is suppressed. These modes are also found to give rise to poloidally asymmetric particle transport. Characteristic scale lengths of these fluctuations are isotropic in the plane transverse to B and smaller than the connection length along the field line. Sheared poloidal flow is self‐consistently driven by both the Reynolds stress and the Stringer mechanisms. In the presence of self‐consistent shear flow, the transverse spectrum is no longer isotropic transverse to B. The vortices become elongated in the poloidal direction. Also, there is a substantial reduction in both the level of fluctuations of the density and potential and the associated particle transport. These features are in qualitative agreemen...","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125596488","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}
引用次数: 224
Relativistic and ponderomotive self‐focusing of a laser beam in a radially inhomogeneous plasma. I. Paraxial approximation 激光束在径向非均匀等离子体中的相对论性和自动机自聚焦。一、近轴近似
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860828
H. Brandi, C. Manus, G. Mainfray, T. Lehner, G. Bonnaud
{"title":"Relativistic and ponderomotive self‐focusing of a laser beam in a radially inhomogeneous plasma. I. Paraxial approximation","authors":"H. Brandi, C. Manus, G. Mainfray, T. Lehner, G. Bonnaud","doi":"10.1063/1.860828","DOIUrl":"https://doi.org/10.1063/1.860828","url":null,"abstract":"The propagation of a high‐irradiance laser beam in a plasma whose optical index depends nonlinearly on the light intensity is investigated through both theoretical and numerical analyses. The nonlinear effects examined herein are the relativistic decrease of the plasma frequency and the ponderomotive expelling of the electrons. This paper is devoted to focusing and defocusing effects of a beam assumed to remain cylindrical and for a plasma supposed homogeneous along the propagation direction but radially inhomogeneous with a parabolic density profile. A two‐parameter perturbation expansion is used; these two parameters, assumed small with respect to unity, are the ratio of the laser wavelength to the radial electric‐field gradient length and the ratio of the plasma frequency to the laser frequency. The laser field is described in the context of a time envelope and spatial paraxial approximations. An analytical expression is provided for the critical beam power beyond which self‐focusing appears; it depend...","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122536172","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}
引用次数: 250
Neoclassical bootstrap current and transport in optimized stellarator configurations 优化仿星器配置中的新古典自举电流和输运
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860843
H. Maassberg, W. Lotz, J. Nührenberg
{"title":"Neoclassical bootstrap current and transport in optimized stellarator configurations","authors":"H. Maassberg, W. Lotz, J. Nührenberg","doi":"10.1063/1.860843","DOIUrl":"https://doi.org/10.1063/1.860843","url":null,"abstract":"The neoclassical bootstrap current properties of optimized stellarators are analyzed in the relevant mean‐free‐path regimes and compared with the neoclassical transport properties. Two methods—global Monte Carlo simulation [Phys. Fluids 31, 2984 (1988)], and local analysis with the drift kinetic equation solver code [Phys. Fluids B 1, 563 (1989)]—are employed and good agreement is obtained. Full consistency with the elimination of the bootstrap current and favorable neoclassical transport are found.","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124419876","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}
引用次数: 43
Sub-Alfvenic plasma expansion 亚阿尔芬等离子体膨胀
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860825
B. Ripin, J. Huba, E. Mclean, C. Manka, T. Peyser, H. Burris, J. Grun
{"title":"Sub-Alfvenic plasma expansion","authors":"B. Ripin, J. Huba, E. Mclean, C. Manka, T. Peyser, H. Burris, J. Grun","doi":"10.1063/1.860825","DOIUrl":"https://doi.org/10.1063/1.860825","url":null,"abstract":"A large ion Larmor radius plasma undergoes a particularly robust form of Rayleigh–Taylor instability when sub‐Alfvenically expanding into a magnetic field. Results from an experimental study of this instability are reported and compared with theory, notably a magnetohydrodynamic (MHD) treatment that includes the Hall term, a generalized kinetic lower‐hybrid drift theory, and with computer simulations. Many theoretical predictions are confirmed while several features remain unexplained. New and unusual features appear in the development of this instability. In the linear stage there is an onset criterion insensitive to the magnetic field, initial density clumping (versus interchange), linear growth rate much higher than in the ‘‘classic’’ MHD regime, and dominant instability wavelength of order of the plasma density scale length. In the nonlinear limit free‐streaming flutes, apparent splitting (bifurcation) of flutes, curling of flutes in the electron cyclotron sense, and a highly asymmetric expansion are ...","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121592285","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}
引用次数: 86
Simulation of collisionless electrostatic velocity‐shear‐driven instabilities 无碰撞静电速度-剪切驱动不稳定性的模拟
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860847
P. Pritchett
{"title":"Simulation of collisionless electrostatic velocity‐shear‐driven instabilities","authors":"P. Pritchett","doi":"10.1063/1.860847","DOIUrl":"https://doi.org/10.1063/1.860847","url":null,"abstract":"The properties of electrostatic instabilities in velocity shear layers in collisionless plasmas are investigated by means of two‐dimensional particle simulations for the case where the ion gyroradius is comparable to the scale length of the velocity shear. For modes exactly perpendicular to the magnetic field, the Kelvin–Helmholtz instability dominates the evolution of the system producing eφ/Te≳1; the observed growth rates show no reduction compared to the hydromagnetic limit. To obtain this result for the case of negative shear (v0y’/Ωi<0), it is necessary to include the kinetic modifications to the structure of the shear layer equilibrium. For finite k∥ in the range 0<k∥/k<0.04, the shorter‐wavelength inhomogeneous‐energy‐density‐driven instability cannot be identified in the simulations, and the upper limit on its excitation is eφ/Te≲2×10−3.","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"178 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133483579","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}
引用次数: 19
Experimental investigation of three-dimensional magnetic reconnection by use of two colliding spheromaks 利用两个碰撞球点进行三维磁重联的实验研究
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860840
Y. Ono, A. Morita, M. Katsurai, M. Yamada
{"title":"Experimental investigation of three-dimensional magnetic reconnection by use of two colliding spheromaks","authors":"Y. Ono, A. Morita, M. Katsurai, M. Yamada","doi":"10.1063/1.860840","DOIUrl":"https://doi.org/10.1063/1.860840","url":null,"abstract":"Experimental investigation of three‐dimensional (3‐D) effects of magnetic reconnection dynamics has been extended by use of axially colliding spheromaks [M. Yamada et al., Phys. Fluids B 3, 2379 (1991)]. The two toroidal shape spheromak plasmas with major radii of 15–20 cm and with parallel toroidal currents of up to 30 kA collide to merge in an external equilibrium field. It is important to note that the present experimental setup allows one to investigate magnetic reconnection comprehensively from both local and global points of view. Reconnection angle θ between the merging field lines is varied by changing the polarity of the internal toroidal field and the magnitude of an external toroidal field. It is observed that the speed of counterhelicity merging with θ∼180° is about three times faster than that of cohelicity merging with θ∼90°. This suggests the significance of a 3‐D effect on the reconnection process. This difference is attributed to the property of the neutral current sheets with and without the magnetic field component parallel to the reconnection (X) line. In the counterhelicity merging, the neutral current sheet is compressed in much shorter time than in the cohelicity merging, resulting in much higher current density and subsequent faster decay of the current sheet. This induces a faster magnetic reconnection. The reconnection speed increases proportionally with the initial approaching speed of the spheromaks, suggesting that a compressible driven reconnection model is consistent with the present reconnection experimental results.","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116366519","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}
引用次数: 116
Fluid analysis of the collisionless magnetohydrodynamic ballooning mode branch in tokamaks 托卡马克无碰撞磁流体动力气胀模式分支的流体分析
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860874
H. Nordman, B. Jhowry, J. Weiland
{"title":"Fluid analysis of the collisionless magnetohydrodynamic ballooning mode branch in tokamaks","authors":"H. Nordman, B. Jhowry, J. Weiland","doi":"10.1063/1.860874","DOIUrl":"https://doi.org/10.1063/1.860874","url":null,"abstract":"The stability of electromagnetic ballooning modes is investigated using a toroidal two‐fluid model allowing for arbitrary Ln/LB (the characteristic scale lengths of density and magnetic‐field inhomogeneities). The ballooning mode equation is solved numerically and the two‐fluid and magnetohydrodynamic stability properties are discussed and compared. The perpendicular compressibility strongly reduces the growth rate and for Ln/LB∼Ln/LT∼1, the mode is completely stabilized.","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126236618","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}
引用次数: 11
Two‐dimensional studies of stimulated Brillouin scattering, filamentation, and self‐focusing instabilities of laser light in plasmas 激光在等离子体中的受激布里渊散射、成丝和自聚焦不稳定性的二维研究
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860845
M. Amin, C. Capjack, P. Frycz, W. Rozmus, V. Tikhonchuk
{"title":"Two‐dimensional studies of stimulated Brillouin scattering, filamentation, and self‐focusing instabilities of laser light in plasmas","authors":"M. Amin, C. Capjack, P. Frycz, W. Rozmus, V. Tikhonchuk","doi":"10.1063/1.860845","DOIUrl":"https://doi.org/10.1063/1.860845","url":null,"abstract":"The parametric interaction of an intense laser beam with ion plasma modes in a two‐dimensional Cartesian geometry has been studied for the first time by avoiding the paraxial optics approximation. This model allows investigation of the competition between forward, sideward, and backward stimulated Brillouin scattering (SBS) along with filamentation and self‐focusing instabilities. It is shown that the SBS saturation level, the angular distribution of transmitted and scattered light, and their temporal dependence are governed mainly by two control parameters: the backward SBS gain coefficient G, and the ratio αsf of the incident beam power to its critical value for the onset of self‐focusing. In the case of large values of G≳15, backward SBS dominates and prevents both self‐focusing and forward SBS. For smaller values of G, the interaction exhibits a complex oscillatory behavior, which corresponds to the competition between backward and forward SBS for αsf≲1, and involves also self‐focusing for higher beam...","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134180683","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}
引用次数: 29
Radio‐frequency‐sheath‐driven edge plasma convection and interaction with the H mode 射频鞘层驱动的边缘等离子体对流及其与H模式的相互作用
Physics of fluids. B, Plasma physics Pub Date : 1993-10-01 DOI: 10.1063/1.860832
D. D'Ippolito, J. Myra, J. Jacquinot, M. Bureš
{"title":"Radio‐frequency‐sheath‐driven edge plasma convection and interaction with the H mode","authors":"D. D'Ippolito, J. Myra, J. Jacquinot, M. Bureš","doi":"10.1063/1.860832","DOIUrl":"https://doi.org/10.1063/1.860832","url":null,"abstract":"It is shown that radio‐frequency (rf) antenna sheaths can bias the edge plasma potential and drive steady‐state convective cells in the scrape‐off layer (SOL). The resulting E×B convective flow opposes the direction of the sheared flow in the SOL induced by the radially decaying Bohm sheath potential. A two‐dimensional fluid simulation shows that the interaction of the opposing poloidal flows produces secondary vortices, which connect the edge of the confined plasma to the antenna limiters, when the antenna–plasma separation is typically of order a few times the local electron skin depth at the antenna. Estimates for typical tokamak edge parameters suggest that the transit time of particles and energy across these vortices is rapid enough to cause the broadening of SOL density and temperature profiles observed during high‐power heating with ion cyclotron range of frequency (ICRF) antennas in monopole phasing. Radio‐frequency‐sheath‐driven convection is also a good candidate to explain the phasing dependen...","PeriodicalId":113346,"journal":{"name":"Physics of fluids. B, Plasma physics","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133053287","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}
引用次数: 66
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