Collisionless magnetic reconnection in the magnetosphere

Magnetic reconnection underlies the physical mechanism of explosive phenomena in the solar atmosphere and planetary magnetospheres, where plasma is usually collisionless. In the standard model of collisionless magnetic reconnection, the diffusion region consists of two substructures: an electron diffusion region is embedded in an ion diffusion region, in which their scales are based on the electron and ion inertial lengths. In the ion diffusion region, ions are unfrozen in the magnetic fields while electrons are magnetized. The resulted Hall effect from the different motions between ions and electrons leads to the production of the in-plane currents, and then generates the quadrupolar structure of out-of-plane magnetic field. In the electron diffusion region, even electrons become unfrozen in the magnetic fields, and the reconnection electric field is contributed by the off-diagonal electron pressure terms in the generalized Ohm's law. The reconnection rate is insensitive to the specific mechanism to break the frozen-in condition, and is on the order of 0.1. In recent years, the launching of Cluster, THEMIS, MMS, and other spacecraft has provided us opportunities to study collisionless magnetic reconnection in the Earth's magnetosphere, and to verify and extend more insights on the standard model of collisionless magnetic reconnection. In this paper, we will review what we have learned beyond the standard model with the help of observations from these spacecraft as well as kinetic simulations.     

一种求解双曲方程新有有限差分算法

本文提出一种适于求解一阶双曲系统的新的差分格式。它的建立方法是：将所要求解的方程与解的空间导数所满足的微分方程同时离散化，然后再通过插值函数构成封闭的离散变量代数方程。在线性情况下的误差分析表明：该格式的幅值与位相误差均小于常用的一，二阶差分格式，当其应于非线性气动方程求解时，基本上可以消除数值扩散与振荡这两种非正常现象。     

一种求解双曲方程新的有限差分算法

本文提出一种适于求解一阶双向系统的新的差分格式。它的建立方法是：将所要求解的方程与解的空间导数所满足的微分方程同时离散化，然后再通过插值函数构成封闭的离散变量代数方程。在线性情况下的误差分析表明：该格式的幅值与位相误差均小于常用的一、二阶差分格式；当其应用于非线性气动方程求解时，基本上可以消除数值扩散与振荡这两种非正常现象。