报告题目：Particle acceleration mechanisms during magnetic reconnection
报告人：Dr. Xiaocan Li, Los Alamos National Laboratory
Particle acceleration in space and astrophysical magnetic reconnection sites is an important unsolved problem. Earlier kinetic simulations have identified several acceleration mechanisms that are associated with particle guiding-center drift motions. Here, we show that, for sufficient large systems, the energization processes due to particle drift motions can be described as fluid compression and shear. By analyzing results from fully kinetic simulations, we show that the compression energization dominates the acceleration of high-energy particles in reconnection with a weak guide field, and the compression and shear effects are comparable when the guide field is 50% of the reconnecting component. Based on this result, we then study the large-scale reconnection acceleration by solving the Parker's transport equation in a background reconnection flow provided by MHD simulations. Due to the compression effect, particles are accelerated to high energies and develop power-law energy distributions. The power-law index and maximum energy depend on guide-field strength and diffusion model. This study clarifies the nature of particle acceleration in reconnection layer, and may be important to understand particle energization during solar flares.
李晓璨博士，2011年于北京大学空间物理专业获得硕士学位，2016年于The University of Alabama in Huntsville获得博士学位，目前在Los Alamos National Lab从事博士后研究工作。主要研究方向为太阳、空间和天体物理中的粒子加速问题。