Comparison between electrostatic PP and PIC simulations on electron bunch expansion

Fuente: arXiv
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Hauptverfasser: Zhang, Yanan, Ma, Xiaochun, Liu, Hui, Zhao, Yinjian
Format: Preprint
Veröffentlicht: 2025
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author Zhang, Yanan
Ma, Xiaochun
Liu, Hui
Zhao, Yinjian
author_facet Zhang, Yanan
Ma, Xiaochun
Liu, Hui
Zhao, Yinjian
contents With the great development of parallel computing techniques, the particle-particle (PP) model has been successfully applied in a number of plasma applications. Comparing to particle-mesh (PM) models, for example the widely used particle-in-cell (PIC) method, PP has the advantages of high accuracy in solving Coulomb interactions. In this paper, it is shown that PP is also advantageous to simulate non-neutral plasmas, such as electron bunch expansion in vacuum. The numerical effects of the macro-particle weight and the time step length are investigated for a PP model, accurate and convergent results can be obtained with less effort. On the contrary, PIC needs to simulate the same problem with extremely large effort. It is found that the simulation accuracy does not grow with reduced cell size monotonously, thus no convergence can be easily obtained. In the long run, PIC must apply large enough domain to cover all the expanding particles and avoid non-physical effects caused by imperfect infinite boundary condition, which may result in too heavy computation and make PIC infeasible.
format Preprint
id arxiv_https___arxiv_org_abs_2502_10640
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Comparison between electrostatic PP and PIC simulations on electron bunch expansion
Zhang, Yanan
Ma, Xiaochun
Liu, Hui
Zhao, Yinjian
Plasma Physics
With the great development of parallel computing techniques, the particle-particle (PP) model has been successfully applied in a number of plasma applications. Comparing to particle-mesh (PM) models, for example the widely used particle-in-cell (PIC) method, PP has the advantages of high accuracy in solving Coulomb interactions. In this paper, it is shown that PP is also advantageous to simulate non-neutral plasmas, such as electron bunch expansion in vacuum. The numerical effects of the macro-particle weight and the time step length are investigated for a PP model, accurate and convergent results can be obtained with less effort. On the contrary, PIC needs to simulate the same problem with extremely large effort. It is found that the simulation accuracy does not grow with reduced cell size monotonously, thus no convergence can be easily obtained. In the long run, PIC must apply large enough domain to cover all the expanding particles and avoid non-physical effects caused by imperfect infinite boundary condition, which may result in too heavy computation and make PIC infeasible.
title Comparison between electrostatic PP and PIC simulations on electron bunch expansion
topic Plasma Physics
url https://arxiv.org/abs/2502.10640