研究已经证实,地面电磁波进入电离层与高能粒子发生波粒相互作用,通过改变其投掷角、动量等发生扩散,导致粒子沉降,进而形成粒子暴.近几十年来,从卫星观测到很多电离层中的粒子暴与地震有关系.本文利用波粒回旋共振耦合理论,结合低轨卫星的观测范围,研究场向电磁波的准线性投掷角扩散系数分布与VLF电磁波频率、带宽、电子能量(0.1-50MeV)、磁壳层(L=1.1-3)等特征物理量的关系,并研究在某个确定的投掷角条件下,电磁波频率与其所引发的电子沉降对应的最小耦合能量的关系.利用这些物理量之间的关系,为卫星观测的高能粒子沉降事例提供理论解释,为从卫星高能粒子探测中提取与地震相关的信息提供理论支持,也为我国计划2016年底将发射的电磁监测试验卫星的数据分析奠定基础.
It has been proved that the ground-based electromagnetic wave can transfer into ionosphere and interact with high- energy particles. By changing the pitch angle and momentum, the particles are imposed to enter the bounce loss cone and drift loss cone, then electron precipitation takes place and the particle bursts form. In recent decades, the relationship has been observed among electromagnetic disturbance and particle bursts and seismic activity based on satellite data. Here, by wave-particle cyclotron resonant interaction combined with the observation range of LEO satellite (about 350-1000 kin), the evolvement trend of the pitch angle quasi-linear diffusion coefficients induced by field-aligned electromagnetic waves, is studied with the change of VLF electromagnetic wave frequency, band width, energies of electron (0.1-20 MeV) and L shell (L = 1.1-3). We also show the relationship between VLF electromagnetic wave frequency and minimum energy of precipitation electron induced by it, under certain pitch angle value. The relationship among these quantities may be used to provide theoretical explanation for satellite observations of energetic particle precipitation examples, to provide guidance for extracting information associated with earthquakes from the detection of high-energy particles on the satellite, and to lay the foundation on the data analysis of China seismo-electromagnetic satellite planned to launch at about the end of 2016.