主持人：刘文副研究员

时间：2025年5月26日（周一）10:00

地点：犀浦校区二教2539会议室

腾讯会议：643-376-296

题目：Particle-In-Cell Simulation on Astrophysical Plasmas

主讲人：王振宇 副研究员

            中国科学院磁约束核聚变物理前沿全国重点实验室

2016年博士毕业于美国奥本大学，2016年9月起在普林斯顿大学做博士后，2019年起在普林斯顿大学等离子体物理实验室任Associate Research Physicist。研究兴趣主要为计算等离子体物理，特别是粒子模拟算法及代码的开发，及其在天体和聚变等离子体中的应用。在美期间作为子课题负责人参与美国能源部基于先进计算的科学发现计划项目(SciDAC High-fidelity Boundary Plasma Simulation)，作为项目骨干参与美国能源部百亿亿级超算应用开发计划(Exascale Computing Project-Whole Device Modeling)，作为PI主持的研究受到美国能源部面上项目资助（DE-SC0017908）。近期由中国科学院引进回国。

Abstract:   Particle-In-Cell (PIC) simulation is a powerful tool to study plasma kinetics. In this talk, I will show applying PIC method on the problems of astrophysical plasmas. Firstly, I present the modeling and interpretation of laser experiments designed to generate high Mach number magnetized collisionless shocks on OMEGA-EP facility. In the experiment, a laser-produced high velocity plasma collides with a magnetized, pre-ablated plasma. Proton radiography shows a moving region of proton deficit followed by a sharp enhancement of proton density. These features are produced by gradients in propagating compressed magnetic field. Our team compare the data to the results of 3D PIC simulations, explain the oblique moving features introduced by density gradients in expanding plasma and by curvature of the imposed magnetic field, and identify the narrowing of proton deficit region width with a signature of strong magnetic overshoot. We determine the boundary of pre-ablated background plasma by comparing with radiography of laser shots with only background plasma present. We measure the strength of magneto-inertial fusion electrical discharge system (MIFEDS) field by magnetic deflection. We conclude that our experiments have reproducibly achieved magnetized shocks with Alfvenic Mach number 3 to 9 in laboratory conditions. Secondly, we investigated 3-D linear instabilities of Harris current sheet under a realistic ion-to-electron mass ratio and a finite guide field. The excitation and 3-D properties of lower hybrid drift instability (LHDI) are demonstrated. We study the properties of current sheet instabilities by employing Gyrokinetic electron and Fully kinetic ion (GeFi) particle simulation code. It is found that part of the energy of the LHDI modes penetrates to the current sheet center in the nonlinear stage. The saturation level of magnetic field at the current sheet center is an order of magnitude smaller than that at the current sheet edge. The GeFi simulation results are compared with the fully kinetic PIC simulations.