量子电动力学—粒子模拟极端等离子体动力学研究

新一代拍瓦激光装置有望将激光强度提升至10²³~10²⁴ W·cm^-2，在此极端强场条件下非线性量子电动力学效应对等离子体动力学过程产生重要影响.相对论电子在强电磁场作用下会同步辐射大量伽马光子，当后者穿过超强电磁场时会级联产生正负电子对.与此同时，这些量子电动力学效应也会反作用于激光等离子体相互作用过程，如辐射阻尼严重影响电子运动过程.为了研究这样极端的等离子体动力学，我们介绍最近几年发展的量子电动力学数值模拟模块，并将其耦合到传统的粒子模拟程序中，即量子电动力学-粒子模拟程序.由于大量新辐射的光子和产生的正负电子对会造成模拟粒子数目的不断增加，我们发展了粒子融合技术来减小模拟规模.利用此量子电动力学-粒子模拟程序，我们对极端强场激光物质相互作用以及极端天体物理现象开展了数值模拟研究.

Study on Extreme Plasma Dynamics by Quantum Electrodynamic Particle-in-Cell Simulations

Next generation petawatt laser facility is expected to reach intensity up to the order of 10²³-10²⁴ W·cm^-2,which may generate electromagnetic fields so strong that nonlinear quantum electrodynamics (QED) processes play a crucial role in plasma dynamics.A large number of γ photons can be emitted through synchrotron radiation from ultrarelativistic electrons,and pair creation process can also be triggered when γ photons traverse electromagnetic fields.In turn,these QED physics can affect plasma dynamics itself significantly,in particular for electron motion under radiation reaction.In order to study such extreme plasma dynamics,we introduce a QED model developed in recent years,which can be coupled with traditional particle-in-cell (PIC) code,i.e.,so-called a QED-PIC code.Due to booming particle number caused by the newly emitted photons and created pairs,we also develop a particle merge algorithm to reduce the computational scale.Several applications of this contemporary QED-PIC code in modeling of ultraintense laser-plasma interaction and extreme astrophysical phenomena are presented.