采用Esirkepov算法的相对论束流多维PIC模拟的数值稳定性
Numerical stability of relativistic beam multidimensional PIC simulations employing the Esirkepov algorithm
摘要：
在基于等离子体的粒子加速器、天体物理现象和相对论带电粒子束的多维粒子模拟中，经常会出现快速增长的数值不稳定性。将不稳定性增长降低到可接受的水平需要更高分辨率的网格、高阶场解算器、电流滤波等，除了时间步长与轴向单元尺寸的某些比率之外，对于这些比率，数值增长率和饱和水平显著降低。本文推导和解决了冷束色散关系的数值不稳定性的多维，相对论，电磁粒子在细胞程序采用标准或科尔-Karkkainnen有限差分场求解器交错网格和常见的Esirkepov电流收集算法。良好的整体协议实现与以前报告的结果的WARP代码。特别是，存在的选择时间步长的不稳定性最小化的解释。此外，提出了一种替代的场插值算法，在超相对论模拟中，对于特定的时间步长，几乎完全消除了不稳定性。
英文摘要：
Rapidly growing numerical instabilities routinely occur in multidimensional particle-in-cell computer simulations of plasma-based particle accelerators, astrophysical phenomena, and relativistic charged particle beams. Reducing instability growth to acceptable levels has necessitated higher resolution grids, high-order field solvers, current filtering, etc. except for certain ratios of the time step to the axial cell size, for which numerical growth rates and saturation levels are reduced substantially. This paper derives and solves the cold beam dispersion relation for numerical instabilities in multidimensional, relativistic, electromagnetic particle-in-cell programs employing either the standard or the Cole-Karkkainnen finite difference field solver on a staggered mesh and the common Esirkepov current-gathering algorithm. Good overall agreement is achieved with previously reported results of the WARP code. In particular, the existence of select time steps for which instabilities are minimized is explained. Additionally, an alternative field interpolation algorithm is proposed for which instabilities are almost completely eliminated for a particular time step in ultra-relativistic simulations.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
