随移动窗推进的带电粒子束团长程传输模拟分析

直接采用粒子模拟方法较难实现带电粒子束团千米量级的长程传输模拟,针对此问题以静电模型为基础,引入移动窗技术,使百米量级的粒子传输窗口与束团同步推进运动,建立了带电粒子束团的长程传输模型。将模拟得到的带电粒子束团径向膨胀特性同包络方程的计算结果进行对比,两者吻合较好,证明了在带电粒子束团长程传输模拟研究中结合移动窗技术的可行性及所建模型的合理性。利用此模型分析了100 MeV相对论电子束团的长程传输过程,发现传输过程中束团的自生电场和磁场在径向上呈高度对称分布,轴向上则呈轻微前冲分布；同时,束团内部粒子的轴向速度分布也会发生变化。利用此模型分析了100 MeV电子束团的长程传输过程及其内部参数和自生场量的变化。

Simulation analysis of long-range propagation of charged particle beams propelled by moving window

It is difficult to simulate the long-distance transport of charged particle clusters above kilometer level by using particle simulation methods directly. To solve this problem, based on the electrostatic model, the moving window technology was introduced to make the 100-meter particle transmission moving window advance with the movement of the cluster, and a long-distance transmission model of the charged particle cluster was established. Compared with the radial expansion characteristics of the charged particle cluster obtained by the simulation with the calculation results of the envelope equation, the two are in good agreement, which proves the feasibility of combining the moving window technology in the simulation study of the long-distance transport of the charged particle cluster and the rationality of the transmission model. This model was further used to analyze the long-range transmission process of the 100 MeV relativistic electron beam cluster and the changes of its internal parameters and self-generated field. It was found that the self-generated electric field and magnetic field of the beam are in a highly symmetrical distribution in the radial direction, and in a slightly forward distribution in the axial direction. At the same time, the axial velocity distribution of the particle inside the beam also changes.