Institute for Fusion Theory and Simulation, Department of Physics, Zhejiang University, 310058 Hangzhou, China.
Shanghai Institute of Optics and Fine Mechanics, 201800 Shanghai, China.
Phys Rev E. 2019 Jul;100(1-1):013208. doi: 10.1103/PhysRevE.100.013208.
A particle-in-cell (PIC) simulation code is used to investigate the transport and energy deposition of an intense proton beam in solid-state material. This code is able to simulate close particle interactions by using a Monte Carlo binary collision model. Such a model takes into account all related interactions between the incident protons and material particles, e.g., proton-nucleus, proton-bound-electron, and proton-free-electron collisions. This code also includes a Monte Carlo model for the collisional ionization and electron-ion recombination as well as the depression of the ionization potential by shielding of surrounding particles. Moreover, for intense proton beams, in order to include collective electromagnetic effects, significantly speed up the simulation, and simultaneously avoid numerical instabilities, an approach that combines the PIC method with a reduced model of high-density plasma based on Ohm's law is used. Simulation results indicate that the collective electromagnetic effects have a significant influence on the transport and energy deposition of proton beams. The Ohmic electric field would increase the stopping power and leads to a shortened range of proton beams in solid. The magnetic field would localize the energy deposition by collimating proton beams, which would otherwise be deflected by the collisions with nuclei.
使用粒子在细胞 (PIC) 模拟代码研究强质子束在固态材料中的输运和能量沉积。该代码能够通过使用蒙特卡罗二进制碰撞模型来模拟近距离粒子相互作用。这种模型考虑了入射质子与材料粒子之间的所有相关相互作用，例如质子-核、质子束缚电子和质子自由电子碰撞。该代码还包括用于碰撞电离和电子-离子复合以及屏蔽周围粒子对电离势抑制的蒙特卡罗模型。此外，对于强质子束，为了包括集体电磁效应，显著加快模拟速度，同时避免数值不稳定性，使用了一种将 PIC 方法与基于欧姆定律的高密度等离子体简化模型相结合的方法。模拟结果表明，集体电磁效应对质子束的输运和能量沉积有显著影响。欧姆电场会增加阻止力，并导致质子束在固体中的射程缩短。磁场通过准直质子束来定位能量沉积，否则质子束会因与原子核碰撞而发生偏折。
