磁场重联中的电子加速机制的数值模拟研究

A NUMERICAL SIMULATION STUDY ON THE MECHANISM OF ELECTRON ACCELERATION IN MAGNETIC RECONNECTION

在应用 2 .5维混合模拟方法研究Petschek模型磁场重联的基础上 ,考察了试验电子被加速的特征 .模拟结果表明 ,稳态的低频重联场能将少量试验电子加速到高能 ,电子的能谱为幂律谱 ,但总体分布函数未发生显著变化 .电子在整个加速过程中被束缚在低磁场的加速区内 ,由重联产生的感应电场Ey 分量对其直接加速 ,根据加速时间和加速区域可以将这些电子分为两种情况 :初始位于加速区和漂移到加速区被加速 .

Based on the study of Petschek magnetic reconnection by using 2.5D hybrid simulation, the acceleration characteristics of the test electrons are inspected. The results show that a few test electrons, accelerated by the low frequency steady reconnection field, can obtain extraordinarily high energy. The energy spectrum of energetic electrons abides the power law, though no remarkable difference can be found in the velocity distribution function of electrons as a whole. The electrons are confined into an area with weak magnetic field where they are accelerated. They are accelerated directly by the E y component of electric field induced by the magnetic reconnection. Two situations of electron accelerations can be classified by the period and location. In one situation the electrons is located initially in the acceleration area, in the other elections drift into the area from somewhere else. They are both speeded up in the acceleration region.