无碰撞磁场重联中磁岛结构及其电子动力学

项目名称： 无碰撞磁场重联中磁岛结构及其电子动力学

项目编号： No.41204103

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 地球物理学和空间物理学

项目作者： 黄灿

作者单位： 中国科学技术大学

项目金额： 25万元

中文摘要： 磁场重联提供了一种磁能快速转化为等离子体动能和热能的机制，它还可以有效的加速带电粒子，并且这些过程主要发生在重联扩散区。虽然目前对于单X线重联中的能量耗散和电子加速，已经研究得较为详细，然而当电流片足够长时，会发生多重X线重联，相邻的两根X线之间会产生一个磁岛，随着时间的演化，磁岛之间会相互合并，电子可以约束在磁岛内被更有效加速。此外，近来Cluster卫星在磁尾的观测表明，重联磁岛内部高能电子通量会有明显增加。然而，多重X线重联过程中磁岛结构及其合并对能量耗散以及电子加速的影响，都有待进一步研究。本项目拟采用二维的全粒子模拟方法，对多重X线重联过程中磁岛的产生、结构的演化及合并进行研究，揭示这些过程中的电子动力学行为。

中文关键词： 磁重联；磁岛；电子加速；粒子模拟；

英文摘要： Magnetic reconnection provides an mechanism on fast converting magnetic energy to plasma kinetic and thermal energies. The charged particles can be accelerated effectively during magnetic reconnection, while the energy conversion mainly occurs in the diffusion region. The mechanisms of energy dissipation and electron acceleration are relatively clear for single X-line magnetic reconnection. However, when the current sheet is sufficiently long, the multiple X-line reconnection occurs. A magnetic island forms between two neighbour X-lines. The magnetic islands can coalesce during the multiple X-line reconnection, meanwhile, electrons can be trapped in magnetic islands and get accelerated. Furthermore, recent observations from Cluster in the magnetotail indicate that the high-energy electron fluxes peak inside the magnetic islands. However, the effects of the magnetic islands and the coalescence of magnetic islands on energy dissipation and electron acceleration during multiple X-line reconnection require further investigations. Two-dimensional full particle simulations are used in this project to study the electron dynamical behaviors in generation, evolution, and coalescense processes of magnetic islands during the multiple X-line reconnection.

英文关键词： Magnetic reconnection；Magnetic island；Electron acceleration；Particle simulation；