报告题目：Nonthermal Particle Acceleration in Magnetic Reconnection
报告人：郭帆 研究员（Los Alamos National Laboratory）
报告人简介：郭帆，2005和2007在中国科技大学获得本科和硕士学位，导师陆全明教授。2012在美国亚利桑那大学获得博士学位，导师Joe Giacalone。2012-2016美国Los Alamos National Laboratory博士后，合作导师李晖教授。2016年转为staff scientist。主要研究日球和天体等离子体物理特别是粒子加速问题。曾获2013 Gerard P. Kuiper Memorial Award。
摘要：Magnetic reconnection is a commonly known multi-scale plasma process that quickly converts magnetic energy into kinetic energy in bulk plasma flow, thermal and nonthermal particle distributions. An important problem that remains unsolved is the acceleration of non-thermal charged particles in the reconnection region. In particular, the large-scale theory and 3D extension of this problem are poorly known. To shed more lights to this problem, we utilize a number of tools to resolve this problem. Using LANL’s VPIC code, we study particle acceleration in magnetic reconnection via large-scale 3D kinetic simulations to examine several effects that may be important, including pre-existing fluctuations, kink and secondary tearing instabilities, and open boundary conditions. The results show that particle acceleration in reconnection layers is surprisingly robust despite the development of 3D turbulence and instabilities. Furthermore, the observed particle acceleration in the 3D simulations is sometimes more efficient than the corresponding 2D case, indicating viable new acceleration mechanisms. We then study the large-scale reconnection acceleration by solving the Parker's transport equation in a background reconnecting flow provided by MHD simulations. Due to the compression effect, the simulations suggest fast particle acceleration to high energies in the reconnection layer. This study clarifies the nature of particle acceleration in reconnection layer, and may be important to understand particle acceleration and plasma energization during solar flares and other astrophysical environments.
时间：3月21日（周二）上午9点
地点：天文楼402会议室
欢迎各位老师、同学参加！
南京大学天文与空间科学学院
