电子束流激发的电子声波数值模拟
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摘要
通过一维静电粒子模拟程序研究了电子束流不稳定性,其中束流电子的温度远大于背景电子的温度.结果发现,所激发的波动主要是电子声波,波动的演化经历了线性增长和非线性饱和两个阶段.在非线性饱和阶段,由于电子声波相速度随频率是变化的,它可以通过非线性相互作用将背景比较冷的电子加速到很高的能量.此外,还研究了束流电子的温度、束流电子和背景电子的相对密度以及束流电子的漂移速度对电子束流不稳定性的影响.
In this paper,we employ an electrostatic particle-in-cell simulation model to study the electron beam instability,in which the temperature of beam electrons is much larger than that of background electrons.Results show that the dominant wave mode excited by the electron beam is the electron acoustic waves,of which the evolution has two stages:the linear growth stage and nonlinear saturation stage.During the nonlinear saturation stage,apart of background electrons can be accelerated to high energy via its nonlinear interactions with excited electron acoustic waves,whose phase velocities change with their frequencies.We also study the effects of the temperature of beam electrons,the density ratio of beam electrons to background electrons,and the drift velocity of beam electrons on the excited electron acoustic waves.
In this paper,we employ an electrostatic particle-in-cell simulation model to study the electron beam instability,in which the temperature of beam electrons is much larger than that of background electrons.Results show that the dominant wave mode excited by the electron beam is the electron acoustic waves,of which the evolution has two stages:the linear growth stage and nonlinear saturation stage.During the nonlinear saturation stage,apart of background electrons can be accelerated to high energy via its nonlinear interactions with excited electron acoustic waves,whose phase velocities change with their frequencies.We also study the effects of the temperature of beam electrons,the density ratio of beam electrons to background electrons,and the drift velocity of beam electrons on the excited electron acoustic waves.
引文
An X,Bortnik J,Van Compernolle B,Decyk V,et al.2017.Electrostatic and whistler instabilities excited by an electron beam.Physics of Plasmas,24(7):072116,doi:10.1063/1.4986511.
Bale S D,Kellogg P J,Larsen D E,et al.1998.Bipolar electrostatic structures in the shock transition region:Evidence of electron phase space holes.Geophysical Research Letters,25(15):2929-2932.
Bernstein I B,Greene J M,Kruskal M D.1957.Exact nonlinear plasma oscillations.Physical Reviews,108(3):546-550.
Cairns I H.1987.Fundamental plasma emission involving ion sound waves.Journal of Plasma Physics,38(2):169-178.
Cattell C,Crumley J,Dombeck J,et al.2002.Polar observations of solitary waves at the Earth′s magnetopause.Geophysical Research Letters,29(5):1065,doi:10.1029/2001GL014046.
Chen L J,Pickett J,Kintner P,et al.2005.On the widthamplitude inequality of electron phase space holes.Journal of Geophysical Research:Space Physics,110(A9):A09211,doi:10.1029/2005JA011087.
Ergun R E,Carlson C W,McFadden J P,et al.1998.Debye-scale plasma structures associated with magnetic-field-aligned electric fields.Physical Review Letters,81(4):826-829.
Franz J R,Kintner P M,Pickett J S.1998.POLAR observations of coherent electric field structures.Geophysical Research Letters,25(8):1277-1280.
Fried B D,Gould R W.1961.Longitudinal ion oscillations in a hot plasma.Physics of Fluids,4(1):139-147.
Fu X R,Lu Q M,Wang S.2006.The process of electron acceleration during collisionless magnetic reconnection.Physics of Plasmas,13(1):012309,doi:10.1063/1.2164808.
Fujimoto K,Machida S.2006.A generation mechanism of electrostatic waves and subsequent electron heating in the plasma sheet-lobe boundary region during magnetic reconnection.Journal of Geophysical Research:Space Physics,111(A9):A09216,doi:10.1029/2005JA011542.
Gao X L,Mourenas D,Li W,et al.2016.Observational evidence of generation mechanisms for very oblique lower band chorus using THEMIS waveform data.Journal of Geophysical Research:Space Physics,121(7):6732-6748,doi:10.1002/2016JA022915.
Gary S P,Feldman W C.1977.Solar wind heat flux regulation by the whistler instability.Journal of Geophysical Research:Space Physics,82(7):1087-1094,doi:10.1029/JA082i007p01087.
Gary S P,Tokar R L.1985.The electron-acoustic mode.Physics of Fluids,28(8):2439.
Ginzburg V L,Zhelezniakov V V.1958.On the possible mechanisms of sporadic solar radio emission(Radiation in an Isotropic Plasma).Soviet Astronomy,2:653.
Gurnett D A,Frank L A.1977.A region of intense plasma wave turbulence on auroral field line.Journal of Geophysical Research,82(7):1031-1050,doi:10.1029/JA082i007p01031.
Hoshino M,Mukai T,Terasawa T,et al.2001.Suprathermal electron acceleration in magnetic reconnection.Journal of Geophysical Research:Space Physics,106(A11):25979-25998,doi:10.1029/2001JA900052.
Huang C,Lu Q M,Wang S.2010.The mechanisms of electron acceleration in antiparallel and guide field magnetic reconnection.Physics of Plasmas,17(7):072306,doi:10.1063/1.3457930.
Huang C,Lu Q M,Wang P R,et al.2014.Characteristics of electron holes generated in the separatrix region during antiparallel magnetic reconnection.Journal of Geophysical Research:Space Physics,119(8):6445-6454,doi:10.1002/2014JA019991.
Koen E J,Collier A B,Maharaj S K.2012.Particle-in-cell simulations of beam-driven electrostatic waves in a plasma.Physics of Plasmas,19(4):042101,doi:10.1063/1.3695402.
Lin C S,Burch J L,Shawhan S D,et al.1984.Correlation of auroral hiss and upward electron beams near the polar cusp.Journal of Geophysical Research:Space Physics,89(A2):925-935,doi:10.1029/JA089iA02p00925.
Lin R P,Hudson H S.1971.10~100keV electron acceleration and emission from solar flares.Solar Physics,17(2):412-435.
Lu Q M,Cai D S.2001.Implementation of parallel plasma particlein-cell codes on PC cluster.Computer Physics Communications,135(1):93-104.
Lu Q M,Wang S,Dou X K.2005a.Electrostatic waves in an electron-beam plasma system.Physics of Plasmas,12(7):072903,doi:10.1063/1.1951367.
Lu Q M,Wang D Y,Wang S.2005b.Generation mechanism of electrostatic solitary structures in the Earth′s auroral region.Journal of Geophysical Research:Space Physics,110(A3):A03223,doi:10.1029/2004JA010739.
Lu Q M,Lembege B,Tao J B,et al.2008.Perpendicular electric field in two-dimensional electron phase-holes:A parameter study.Journal of Geophysical Research:Space Physics,113(A11):A11219,doi:10.1029/2008JA013693.
Lu QM,Huang C,Xie J L,et al.,2010.Features of separatrix regions in magnetic reconnection:Comparison of 2-D particle-incell simulations and Cluster observations.Journal of Geophysical Research:Space Physics,115(A11):A11208,doi:10.1029/2010JA015713.
Markovskii S A,Hollweg J V.2002.Electron heat flux instabilities in coronal holes:Implications for ion heating.Geophysical Research Letters,29(17):1843,doi:10.1029/2002GL015189.
Matsumoto H,Kojima H,Miyatake T,et al.1994.Electrostatic solitary waves(ESW)in the magnetotail:BEN wave forms observed by GEOTAIL.Geophysical Research Letters,21(25):2915-2918,doi:10.1029/94GL01284.
Melrose D B.1980.The emission mechanisms for solar radio bursts.Space Science Reviews,26(1):3-38.
Miller J A,Cargill P J,Emslie A G,et al.1997.Critical issues for understanding particle acceleration in impulsive solar flares.Journal of Geophysical Research:Space Physics,102(A7):14631-14660,doi:10.1029/97JA00976.
Mourenas D,Artemyev A V,Agapitov O V,et al.2015.Very oblique whistler generation by low-energy electron streams.Journal of Geophysical Research:Space Physics,120(5):3665-3683,doi:10.1002/2015JA021135.
Muschietti L,Ergun R E,Roth I,et al.1999.Phase-space electron holes along magnetic field lines.Geophysical Research Letters,26(8):1039-1096.
Omura Y,Matsumoto H,Miyake T,et al.1996.Electron beam instabilities as generation mechanism of electrostatic solitary waves in the magnetotail.Journal of Geophysical Research:Space Physics,101(A2):2685-2698,doi:10.1029/95JA03145.
Pickett J S,Chen L J,Kahler S W,et al.2004.Isolated electrostatic structures observed throughout the Cluster orbit:Relationship to magnetic field strength.Annales Geophysicae,22(7):2515-2523.
Pottelette R,Ergun R E,Treumann R A,et al.1999.Modulated electron-acoustic waves in auroral density cavities:FASTobservations.Geophysical Research Letters,26(16):2629-2632,doi:10.1029/1999GL900462.
Tokar R L,Gurnett D A,Feldman W C.1984.Whistler mode turbulence generated by electron beams in Earth's bow shock.Journal of Geophysical Research:Space Physics,89(A1):105-114,doi:10.1029/JA089iA01p00105.
Wang R S,Lu Q M,Huang C,et al.2010.Multispacecraft observation of electron pitch angle distributions in magnetotail reconnection.Journal of Geophysical Research:Space Physics,115(A1):A01209,doi:10.1029/2009JA014553.
Wu M Y,Lu Q M,Huang C,et al.2010a.Transverse instability and perpendicular electric field in two-dimensional electron phase-space holes.Journal of Geophysical Research:Space Physics,115(A10):A10245,doi:10.1029/2009JA015235.
Wu M Y,Wu H,Lu Q M,et al.2010b.Effects of perpendicular thermal velocities on the transverse instability in electron phase space holes.Chinese Physics Letters,27(9):095201,doi:10.1088/0256-307X/27/9/095201.
Yoon P H.1995.Plasma emission by a nonlinear beam instability.Physics of Plasmas,2(2):537,doi:10.1063/1.870979.
Bale S D,Kellogg P J,Larsen D E,et al.1998.Bipolar electrostatic structures in the shock transition region:Evidence of electron phase space holes.Geophysical Research Letters,25(15):2929-2932.
Bernstein I B,Greene J M,Kruskal M D.1957.Exact nonlinear plasma oscillations.Physical Reviews,108(3):546-550.
Cairns I H.1987.Fundamental plasma emission involving ion sound waves.Journal of Plasma Physics,38(2):169-178.
Cattell C,Crumley J,Dombeck J,et al.2002.Polar observations of solitary waves at the Earth′s magnetopause.Geophysical Research Letters,29(5):1065,doi:10.1029/2001GL014046.
Chen L J,Pickett J,Kintner P,et al.2005.On the widthamplitude inequality of electron phase space holes.Journal of Geophysical Research:Space Physics,110(A9):A09211,doi:10.1029/2005JA011087.
Ergun R E,Carlson C W,McFadden J P,et al.1998.Debye-scale plasma structures associated with magnetic-field-aligned electric fields.Physical Review Letters,81(4):826-829.
Franz J R,Kintner P M,Pickett J S.1998.POLAR observations of coherent electric field structures.Geophysical Research Letters,25(8):1277-1280.
Fried B D,Gould R W.1961.Longitudinal ion oscillations in a hot plasma.Physics of Fluids,4(1):139-147.
Fu X R,Lu Q M,Wang S.2006.The process of electron acceleration during collisionless magnetic reconnection.Physics of Plasmas,13(1):012309,doi:10.1063/1.2164808.
Fujimoto K,Machida S.2006.A generation mechanism of electrostatic waves and subsequent electron heating in the plasma sheet-lobe boundary region during magnetic reconnection.Journal of Geophysical Research:Space Physics,111(A9):A09216,doi:10.1029/2005JA011542.
Gao X L,Mourenas D,Li W,et al.2016.Observational evidence of generation mechanisms for very oblique lower band chorus using THEMIS waveform data.Journal of Geophysical Research:Space Physics,121(7):6732-6748,doi:10.1002/2016JA022915.
Gary S P,Feldman W C.1977.Solar wind heat flux regulation by the whistler instability.Journal of Geophysical Research:Space Physics,82(7):1087-1094,doi:10.1029/JA082i007p01087.
Gary S P,Tokar R L.1985.The electron-acoustic mode.Physics of Fluids,28(8):2439.
Ginzburg V L,Zhelezniakov V V.1958.On the possible mechanisms of sporadic solar radio emission(Radiation in an Isotropic Plasma).Soviet Astronomy,2:653.
Gurnett D A,Frank L A.1977.A region of intense plasma wave turbulence on auroral field line.Journal of Geophysical Research,82(7):1031-1050,doi:10.1029/JA082i007p01031.
Hoshino M,Mukai T,Terasawa T,et al.2001.Suprathermal electron acceleration in magnetic reconnection.Journal of Geophysical Research:Space Physics,106(A11):25979-25998,doi:10.1029/2001JA900052.
Huang C,Lu Q M,Wang S.2010.The mechanisms of electron acceleration in antiparallel and guide field magnetic reconnection.Physics of Plasmas,17(7):072306,doi:10.1063/1.3457930.
Huang C,Lu Q M,Wang P R,et al.2014.Characteristics of electron holes generated in the separatrix region during antiparallel magnetic reconnection.Journal of Geophysical Research:Space Physics,119(8):6445-6454,doi:10.1002/2014JA019991.
Koen E J,Collier A B,Maharaj S K.2012.Particle-in-cell simulations of beam-driven electrostatic waves in a plasma.Physics of Plasmas,19(4):042101,doi:10.1063/1.3695402.
Lin C S,Burch J L,Shawhan S D,et al.1984.Correlation of auroral hiss and upward electron beams near the polar cusp.Journal of Geophysical Research:Space Physics,89(A2):925-935,doi:10.1029/JA089iA02p00925.
Lin R P,Hudson H S.1971.10~100keV electron acceleration and emission from solar flares.Solar Physics,17(2):412-435.
Lu Q M,Cai D S.2001.Implementation of parallel plasma particlein-cell codes on PC cluster.Computer Physics Communications,135(1):93-104.
Lu Q M,Wang S,Dou X K.2005a.Electrostatic waves in an electron-beam plasma system.Physics of Plasmas,12(7):072903,doi:10.1063/1.1951367.
Lu Q M,Wang D Y,Wang S.2005b.Generation mechanism of electrostatic solitary structures in the Earth′s auroral region.Journal of Geophysical Research:Space Physics,110(A3):A03223,doi:10.1029/2004JA010739.
Lu Q M,Lembege B,Tao J B,et al.2008.Perpendicular electric field in two-dimensional electron phase-holes:A parameter study.Journal of Geophysical Research:Space Physics,113(A11):A11219,doi:10.1029/2008JA013693.
Lu QM,Huang C,Xie J L,et al.,2010.Features of separatrix regions in magnetic reconnection:Comparison of 2-D particle-incell simulations and Cluster observations.Journal of Geophysical Research:Space Physics,115(A11):A11208,doi:10.1029/2010JA015713.
Markovskii S A,Hollweg J V.2002.Electron heat flux instabilities in coronal holes:Implications for ion heating.Geophysical Research Letters,29(17):1843,doi:10.1029/2002GL015189.
Matsumoto H,Kojima H,Miyatake T,et al.1994.Electrostatic solitary waves(ESW)in the magnetotail:BEN wave forms observed by GEOTAIL.Geophysical Research Letters,21(25):2915-2918,doi:10.1029/94GL01284.
Melrose D B.1980.The emission mechanisms for solar radio bursts.Space Science Reviews,26(1):3-38.
Miller J A,Cargill P J,Emslie A G,et al.1997.Critical issues for understanding particle acceleration in impulsive solar flares.Journal of Geophysical Research:Space Physics,102(A7):14631-14660,doi:10.1029/97JA00976.
Mourenas D,Artemyev A V,Agapitov O V,et al.2015.Very oblique whistler generation by low-energy electron streams.Journal of Geophysical Research:Space Physics,120(5):3665-3683,doi:10.1002/2015JA021135.
Muschietti L,Ergun R E,Roth I,et al.1999.Phase-space electron holes along magnetic field lines.Geophysical Research Letters,26(8):1039-1096.
Omura Y,Matsumoto H,Miyake T,et al.1996.Electron beam instabilities as generation mechanism of electrostatic solitary waves in the magnetotail.Journal of Geophysical Research:Space Physics,101(A2):2685-2698,doi:10.1029/95JA03145.
Pickett J S,Chen L J,Kahler S W,et al.2004.Isolated electrostatic structures observed throughout the Cluster orbit:Relationship to magnetic field strength.Annales Geophysicae,22(7):2515-2523.
Pottelette R,Ergun R E,Treumann R A,et al.1999.Modulated electron-acoustic waves in auroral density cavities:FASTobservations.Geophysical Research Letters,26(16):2629-2632,doi:10.1029/1999GL900462.
Tokar R L,Gurnett D A,Feldman W C.1984.Whistler mode turbulence generated by electron beams in Earth's bow shock.Journal of Geophysical Research:Space Physics,89(A1):105-114,doi:10.1029/JA089iA01p00105.
Wang R S,Lu Q M,Huang C,et al.2010.Multispacecraft observation of electron pitch angle distributions in magnetotail reconnection.Journal of Geophysical Research:Space Physics,115(A1):A01209,doi:10.1029/2009JA014553.
Wu M Y,Lu Q M,Huang C,et al.2010a.Transverse instability and perpendicular electric field in two-dimensional electron phase-space holes.Journal of Geophysical Research:Space Physics,115(A10):A10245,doi:10.1029/2009JA015235.
Wu M Y,Wu H,Lu Q M,et al.2010b.Effects of perpendicular thermal velocities on the transverse instability in electron phase space holes.Chinese Physics Letters,27(9):095201,doi:10.1088/0256-307X/27/9/095201.
Yoon P H.1995.Plasma emission by a nonlinear beam instability.Physics of Plasmas,2(2):537,doi:10.1063/1.870979.