等离子体层嘶声波对辐射带电子投掷角散射系数的多维建模  

Multi-dimensional modeling of radiation belt electron pitch-angle diffusion coefficients caused by plasmaspheric hiss

作　　者：王敬之 马新 项正 顾旭东[1] 焦鹿怀 雷良建 倪彬彬[1] Wang Jing-Zhi;Ma Xin;Xiang Zheng;Gu Xu-Dong;Jiao Lu-Huai;Lei Liang-Jian;Ni Bin-Bin(Department of Space Physics,School of Electronic Information,Wuhan University,Wuhan 430072,China;Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]武汉大学电子信息学院,武汉430072 [2]中国科学院地质与地球物理研究所,地球与行星物理重点实验室,北京100029

出　　处：《物理学报》2022年第22期363-376,共14页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:42025404,42188101,42174190,41904143,42274199,42204160);民用航天预研项目资助课题(批准号:D020308,D020104);中国科学院战略性先导科技专项(B类)(批准号:XDB41000000)、中国科学院地质与地球物理研究所地球与行星物理重点实验室开放课题(批准号:DQXX2021-04);中央高校基本科研业务费专项资金(批准号:2042021kf0016)资助的课题。

摘　　要：等离子体层嘶声波(plasmaspheric hiss)是地球辐射带中一种常见的电磁波动.嘶声波可以通过波粒相互作用将辐射带电子散射进入损失锥进而沉降到中性大气,因此是导致辐射带电子损失的重要波动源.作为电子能量和投掷角的变化函数,嘶声波对辐射带电子的散射系数受到太阳风和地磁活动水平的显著影响,还强烈依赖于空间位置、背景磁场和等离子体密度分布.为了快速获取嘶声波对辐射带电子的投掷角散射系数以用于辐射带全球动态变化过程建模,本文利用FDC(full diffusion code)系统计算了嘶声波对辐射带电子的散射系数,建立了空间区域L=1.5—6、冷等离子体参数a^(*)=3—30、电子能量1 keV—10 MeV、电子投掷角0°—90°范围内的四维散射系数矩阵数据库.基于该数据库,可通过线性插值快速得到不同L和a^(*)参数下的嘶声波对辐射带电子的散射系数.通过对比FDC计算的散射系数与线性插值的结果,验证了基于数据库线性插值得到散射系数的准确性,大部分误差位于10%以内.本文建立的嘶声波对辐射带电子的投掷角散射系数四维数据库和验证的线性插值方法,可以大幅降低获取嘶声波散射系数全球信息的时间,从而快速提升开展长时间辐射带时空变化模拟的计算效率,进而有望为开发地球辐射带动态预报模型提供有利条件.Plasmaspheric hiss is an important wave mode in the Earth’s radiation belts.Hiss waves can scatter energetic electrons into loss cones to precipitate into the atmosphere,and therefore become an important source of fluctuations,leading the radiation belt to lose electrons.As a function of electron energy and pitch angle,the diffusion coefficient of hiss waves for radiation belt electrons is significantly influenced by the solar wind and geomagnetic activity,and also strongly depends on the spatial position,the background magnetic field,and the plasma density distribution.In order to quickly obtain the diffusion coefficients of hiss waves on electrons in the radiation belt for modelling the global dynamics of the radiation belt,we systematically calculate the diffusion coefficients of hiss waves on electrons in the radiation belt by using the full diffusion code(FDC),and build a four-dimensional matrix database of diffusion coefficients for the spatial region L=1.5-6,the cold plasma parameter a^(*)=3-30,electron energy 1 keV-10 MeV,and electron throw angle 0°–90°.According to the database,we can quickly obtain diffusion coefficients with different L and a^(*)values through linear interpolations.By comparing the errors between diffusion coefficients calculated by the FDC code and those linearly interpolated from the diffusion coefficient database,the accuracies of interpolated coefficients are validated,showing that most of the errors lie in 10%.The four-dimensional database of hiss wave pitch angle diffusion coefficients for radiation belt electrons and the validated linear interpolation method established in this paper can significantly reduce the time required to obtain global information about hiss wave diffusion coefficients,thereby rapidly improving the computational efficiency of carrying out simulations of spatial and temporal changes in the radiation belts over long periods of time,which in turn is expected to provide favourable conditions for the development of dynamic forecasting models of the Earth

关 键 词：辐射带电子 等离子体层嘶声 散射系数 线性插值 波粒相互作用 

分 类 号：P354[天文地球—空间物理学] O441.4[天文地球—地球物理学]