Department of Aerospace Engineering, University of Maryland, 3146 Glenn L. Martin Hall, College Park, Maryland 20740, USA.
Phys Rev E. 2017 Jun;95(6-1):063209. doi: 10.1103/PhysRevE.95.063209. Epub 2017 Jun 29.
In kinetic simulations of non-Maxwellian plasmas, the calculation of particle scattering due to Coulomb collisions has no simple approximation. In such simulations, the number of collision interactions a particle experiences in a single time step is typically too large for direct calculation. In this work, the cumulative effect of a series of binary collisions is calculated numerically in a stochastic manner, and heuristic trends are produced as functions of the local plasma parameters. The result is a collision model suitable for implementation into a kinetic plasma simulation. The presence of low-probability, high-angle scattering due to close collision encounters is defined and described, and this effect is demonstrated in a test problem simulation of weakly collisional counterstreaming ion beams.
在非麦克斯韦尔等离子体的动力学模拟中，由于库仑碰撞导致的粒子散射的计算没有简单的近似。在这种模拟中，单个时间步内粒子经历的碰撞相互作用的数量通常太大，无法直接计算。在这项工作中，以随机的方式数值计算一系列二元碰撞的累积效应，并生成作为局部等离子体参数函数的启发式趋势。结果是一个适合于实现到动力学等离子体模拟中的碰撞模型。由于近距离碰撞而导致的低概率、大角度散射的存在被定义和描述，并且这种效应在弱碰撞反向离子束的测试问题模拟中得到了验证。
