报告题目：Particle acceleration mechanisms during magnetic reconnection

　　报告摘要：Particle acceleration in space and astrophysical magnetic reconnection sites is an important unsolved problem in studies of magnetic reconnection. 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.

　　报告人：李晓璨 博士 （Los Alamos National Laboratory）

　　报告时间：2018年5月16日 （星期三）下午2:00

　　报告地点：仙林3-302会议室

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