外辐射带波粒相互作用的观测分析与数值模拟
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摘要
本文利用Van Allen Probes卫星观测数据研究了2013年3月17日至18日强磁暴期间外辐射带高能电子通量(1.8-2.6 M e V)的演化。观测结果显示,在磁暴恢复期间,高能电子通量增涨约50-100倍。在L=4.1的附近,Van Allen Probes同步观测到高强度的合声波。本文基于高斯分布的哨声波谱密度分布和偶极子背景磁场模型,计算了弹跳平均电子共振扩散系数,并通过求解Fokker-Planck扩散方程对高能电子相空间密度的演化过程进行了估算。数值计算结果表明,观测到的合声波能够与辐射带高能电子产生回旋共振作用,有效地加速高能电子。本文的观测和模拟结果为合声波加速竞争机制引起的辐射带高能电子演化过程提供了一定依据。
The paper studies the evolution of relativistic electron fluxes( 1.8-2.6 Me V) in the outer radiation belt during the strong geomagnetic storm on March 17 to 18,2013 using Van Allen Probes observations. The relativistic electron flux increased by50-100 times during the recovery phase,and Van Allen Probes simultaneously observed intensified chorus waves at L = 4.1. The research calculates the bounce-averaged resonant electron diffusion coefficients with Gaussian distributions and a dipole geomagnetic field model,then estimates the evolution of relativistic electron phase space density through Fokker-Planck diffusion equation solution. The numerical simulations indicate that the observed chorus waves could accelerate the high-energy electrons with gyro-resonance interaction. The present observation and modeling results provide a further evidence for the competing mechanisms of chorus-driven acceleration contributing to the relativistic electron evolution in the outer radiation belt.
The paper studies the evolution of relativistic electron fluxes( 1.8-2.6 Me V) in the outer radiation belt during the strong geomagnetic storm on March 17 to 18,2013 using Van Allen Probes observations. The relativistic electron flux increased by50-100 times during the recovery phase,and Van Allen Probes simultaneously observed intensified chorus waves at L = 4.1. The research calculates the bounce-averaged resonant electron diffusion coefficients with Gaussian distributions and a dipole geomagnetic field model,then estimates the evolution of relativistic electron phase space density through Fokker-Planck diffusion equation solution. The numerical simulations indicate that the observed chorus waves could accelerate the high-energy electrons with gyro-resonance interaction. The present observation and modeling results provide a further evidence for the competing mechanisms of chorus-driven acceleration contributing to the relativistic electron evolution in the outer radiation belt.
引文
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[8] XIAO Fuliang,SU Zhenpeng,ZHENG Huinan,et al. Threedimensional simulations of outer radiation belt electron dynamics including cross-diffusion terms[J]. J. Geophys. Res.,2010,115:A05216.
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[10]TSURUTANI B T,VERKHOGLYADOVA O P,LAKHINA G S,et al. Properties of dayside outer zone chorus during HILDCAA events:Loss of energetic electrons[J]. J. Geophys. Res.,2009,114:A03207.
[11]苏振鹏.电子辐射带形成和演化的全球动力学模型[D].合肥:中国科学技术大学,2011.
[12]LYONS L R,THORNE R M,KENNEL C F. Pitch-angle diffusion of radiation belt electrons w ithin the plasmasphere[J]. J.Geophys. Res.,1972,77(19):3455-3474.
[13]SU Zhenpeng,ZHENG Huinan,WANG Shui. Dynamic evolution of energetic outer zone electrons due to w histler-mode chorus based on a realistic density model[J]. J. Geophys. Res.,2009,114:A07201.
[14]THORNE R M,O’BRIEN T P,SHPRITS Y Y,et al. Timescale for M e V electron microburst loss during geomagnetic storms[J]. J.Geophys. Res.,2005,110:A09202.
[15]GLAUERT S A,HORNE R B. Calculation of pitch angle and energy diffusion coefficients w ith the PADIE code[J]. J. Geophys.Res.,2005,110:A04206.
[16]VASYLIUNAS V M. A survey of low-energy electrons in the evening sector of the magnetosphere w ith ogo 1 and ogo 3[J]. J.Geophys. Res. 1968,73(9):2839-2884.
[17] VIAS A F, MACE R L, BENSON R F. Dispersion characteristics for plasma resonances of M axw ellian and kappa distribution plasmas and their comparisons to the IM AGE/RPI observations[J]. J. Geophys. Res.,2005,110:A06202.
[18]XIAO Fuliang, SHEN Chenglong, WANG Yuming, et al.Energetic electron distributions fitted w ith a relativistic kappa-type function at geosynchronous orbit[J]. J. Geophys. Res. 2008,113:A05203.
[2]SUMMERS D,THORNE R M,XIAO Fuliang. Relativistic theory of w ave-particle resonant diffusion w ith application to electron acceleration in the magnetosphere[J]. J. Geophys.Res. 1998,103(A9):20487-20500.
[3] SUMMERS D,MA C,MEREDITH N P,et al. Model of the energization of outer-zone electrons by w histler-mode chorus during the October 9,1990 geomagnetic storm[J]. Geophys. Res.Lett.,2002,29(24):2174-2197.
[4]HORNE R B,THORNE R M,GLAUERT S A,et al. Timescale for radiation belt electron acceleration by w histler mode chorus w aves[J]. J.Geophys. Res.,2005,110:A03225.
[5]TAO Xin,CHAN A A,ALBERT J M,et al. Stochastic modeling of multi-dimensional diffusion in the radiation belts[J]. J.Geophys. Res.,2008,113:A07212.
[6]THORNE R M. LI W,NN B B. et al. Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus[J].Nature,2013,504:,411-414.
[7] XIAO Fuliang,SU Zhenpeng,ZHENG Huinan,et al. 2009.M odeling of outer radiation belt electrons by multidimensional diffusion process[J]. J. Geophys. Res.,2009,114:A03201.
[8] XIAO Fuliang,SU Zhenpeng,ZHENG Huinan,et al. Threedimensional simulations of outer radiation belt electron dynamics including cross-diffusion terms[J]. J. Geophys. Res.,2010,115:A05216.
[9]MAUK B H,FOX N J,KANEKAL S G. et al. Science objectives and rationale for the radiation belt storm probes mission[J]. Space Sci. Rev.,2012,179(1/2/34):3-27.
[10]TSURUTANI B T,VERKHOGLYADOVA O P,LAKHINA G S,et al. Properties of dayside outer zone chorus during HILDCAA events:Loss of energetic electrons[J]. J. Geophys. Res.,2009,114:A03207.
[11]苏振鹏.电子辐射带形成和演化的全球动力学模型[D].合肥:中国科学技术大学,2011.
[12]LYONS L R,THORNE R M,KENNEL C F. Pitch-angle diffusion of radiation belt electrons w ithin the plasmasphere[J]. J.Geophys. Res.,1972,77(19):3455-3474.
[13]SU Zhenpeng,ZHENG Huinan,WANG Shui. Dynamic evolution of energetic outer zone electrons due to w histler-mode chorus based on a realistic density model[J]. J. Geophys. Res.,2009,114:A07201.
[14]THORNE R M,O’BRIEN T P,SHPRITS Y Y,et al. Timescale for M e V electron microburst loss during geomagnetic storms[J]. J.Geophys. Res.,2005,110:A09202.
[15]GLAUERT S A,HORNE R B. Calculation of pitch angle and energy diffusion coefficients w ith the PADIE code[J]. J. Geophys.Res.,2005,110:A04206.
[16]VASYLIUNAS V M. A survey of low-energy electrons in the evening sector of the magnetosphere w ith ogo 1 and ogo 3[J]. J.Geophys. Res. 1968,73(9):2839-2884.
[17] VIAS A F, MACE R L, BENSON R F. Dispersion characteristics for plasma resonances of M axw ellian and kappa distribution plasmas and their comparisons to the IM AGE/RPI observations[J]. J. Geophys. Res.,2005,110:A06202.
[18]XIAO Fuliang, SHEN Chenglong, WANG Yuming, et al.Energetic electron distributions fitted w ith a relativistic kappa-type function at geosynchronous orbit[J]. J. Geophys. Res. 2008,113:A05203.