无碰撞磁重联中电子动力学的理论和实验室研究

项目名称： 无碰撞磁重联中电子动力学的理论和实验室研究

项目编号： No.41331067

项目类型： 重点项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 陆全明

作者单位： 中国科学技术大学

项目金额： 305万元

中文摘要： 磁重联是指等离子体电流片中磁力线自发或被强迫断开和重新联接的过程，它提供了一种将磁场能量快速转化为等离子体动能和热能的物理机制。磁重联和空间等离子体中的许多爆发现象，如磁层亚暴、太阳耀斑等，密切相关。GEM系列研究的结果表明，离子扩散区中由离子和电子的分离运动引起的Hall效应决定了无碰撞磁重联区的结构和重联速度的快慢。但是在GEM系列研究中，初始时刻有一人为加的小扰动，重联是由该小扰动触发的。这也意味着GEM系列研究没有考虑重联的初始触发机制。而最近的研究表明无碰撞磁重联的触发和电子扩散区内的电子动力学过程密切相关，电子扩散区还有可能被拉长并形成次级磁岛。本项目拟采用粒子模拟和实验室研究等手段，并结合卫星观测资料来研究磁重联中电子扩散区的电子动力学行为，揭示无碰撞磁重联的触发和电子扩散区中次级磁岛的形成机制，以及其中的电子加速过程。实验室研究拟在我校的线性磁化等离子体装置上进行。

中文关键词： 无碰撞磁重联;电子扩散区;触发机制;次级磁岛;电子加速

英文摘要： Magnetic reconnection is a process, where the magnetic field lines are spontaneously or forcedly broken and then reconnected in the plasma current sheet, and it provides a physical mechanism for fast conversion from magnetic energy to plasma bulk kinetic energy and thermal energy. Magnetic reconnection is considered to relate to many explosive phenomena in space plasma, such as substorm in the magnetotail and solar flare. The studies of GEM magnetic reconnection challenge have shown that the Hall effect due to the ion and electron decoupling in the ion diffusion region determines the structure and rate of the reconnection. However, a small initial perturbation are added in the studies of GEM magnetic reconnection challenge, which trigger the reconnection. The onset of the magnetic reconnection is ignored in the studies of GEM magnetic reconnection challenge. Recent studies have shown that the onset of collisionless magnetic reconnection is related to electron dynamics in the electron diffusion region, which may be extended and then unstable to secondary islands. We will use particle-in-cell simulations and laboratory experiments, as well as spacecraft data to study electron dynamics in the electron diffusion region of magnetic reconnection to reveal the physical mechanisms of the onset of magnetic reconnection and formation of secondary islands in the electron diffusion region. The process of electron acceleration in magnetic reconnection is also the scope of our research. The experiments on reconnection will be implemented on the linearly magnetized plasma device in our university.

英文关键词： collisionless magnetic reconne;electron diffusion region;onset mechanism;secondary island;electron acceleration