哨声模合声波与地球同步轨道高能电子通量增强事件事例研究

局部加速机制是磁暴期间地球外辐射带高能电子通量增强事件发生的重要原 因. 此加速机制需要两个基本条件, 一是存在种子电子, 二是存在能与种子 电子产生共振的加速波动, 包括哨声模合声波. 通过对2004-2006年 Pi1地磁脉动持续时间与种子电子通量的相关性分析, 更明确提出Pi1地磁脉 动的持续时间可以作为种子电子通量的指示剂. 通过对三个磁暴事例地球同 步轨道的种子电子通量、高能电子通量及哨声模合声波变化情况的分析, 发 现在高能电子通量较强的事例中, 均观测到较高的种子电子通量和较强的 哨声模合声波, 这在一定程度上验证了哨声模合声波对种子电子的回旋加速 机制, 且合声波强度与高能电子通量有正的相关性. 

Study on High Energy Electron Flux Enhancement Events and Whistler Chorus Wave

The local acceleration mechanism is one of the crucial factors for the high energy electron flux enhancement events in the outer radiation belt. There are two substantial preconditions for this acceleration mechanism. The first and the most important one is the presence of enough low energy electron (on the order of tens to hundreds of keV), so-called seed electron; the other is the enhancement of plasma waves including whistler chorus waves which can contribute to the electron acceleration by wave-particle interaction. Geomagnetic field data observed by Memambetsu (L=1.57) observatory are used to extract Pi1 pulsation during 2004-2006. The linear correlation between Pi1 pulsation duration and seed electron flux (LANL 50～225keV) is greater than 0.7, which indicates that the Pi1 pulsation duration is a good indicator of seed electron flux. After the investigation of three magnetic storms events in 2005, the evidence had been found for acceleration of seed electrons to high energies by whistler chorus waves and the positive correlation between the chorus waves' spectral density and high energy electron flux.