磁重联X线附近区域的等离子体结构分布及其演化

Distribution and evolution of plasma structure in region near X-line of magnetic reconnection

高能电子是磁重联中产生的重要现象,卫星Wind和Cluster在磁重联的多个区域都观测到了高能电子。针对X型磁重联,结合粒子动力学方程的部分解析表达式和Hall MHD计算机数值模拟结果,研究了X线附近区域的电子和离子运动的分离特性,得到了该区域垂直重联平面的磁场分量和速度分量随时间的演化特征。研究结果表明,磁重联过程中起支配作用的电子的运动是高度结构化的,受多种因素作用,其运动速度呈现非线性变化的特点,在垂直重联平面z方向的磁场分量和速度分量都存在拐点,拐点前后磁重联的电场分量的波动特性有明显差异。

The event of high-energy electrons is an important phenomenon during magnetic reconnection. High-energy electrons are observed in several magnetic reconnection regions by spacecraft, such as Wind and Cluster. Based on the partially analytical expression of the particle dynamical equations and the result of Hall MHD computer numerical simulation, the decoupling between electron and ion in the region near X- line was studied in the case of X-type magnetic reconnection in this paper. The time-evolution characteristic of the magnetic field component and the speed component in the z-direction which is perpendicular to the reconnection plane was obtained in this region. Our results showed that the motion of electrons which played a dominant role was highly structured in the magnetic reconnection process. Affected by multiple factors, their velocities presented non-linear as well. The magnetic field component and velocity component in the z-direction were with inflection points. There were significant differences between before and after the inflection point in the aspect of wave characteristics of electric-field intensity.