Diagnosing numerical Cherenkov instabilities in relativistic plasma simulations based on general meshes

JOURNAL OF COMPUTATIONAL PHYSICS

卷:402

Article

Na, D-Y^1,2  Nicolini, J. L.^1,2  Lee, R.^1,2  Borges, B-H, V³  Omelchenko, Y. A.⁴  Teixeira, F. L.^1,2 

[1] Ohio State Univ, Electrosci Lab, Columbus, OH 43212 USA

[2] Ohio State Univ, Dept Elect & Comp Engn, Columbus, OH 43212 USA

[3] Univ Sao Paulo, Dept Elect & Comp Engn, BR-13566590 Sao Carlos, SP, Brazil

[4] Trinum Res Inc, San Diego, CA 92126 USA

关键词: Particle-in-cell;    Numerical Cherenkov radiation;    Finite element method;    Plasmas;   

DOI  :  10.1016/j.jcp.2019.108880

来源: Elsevier

【 摘 要 】

Numerical Cherenkov radiation (NCR) or instability is a detrimental effect frequently found in electromagnetic particle-in-cell (EM-PIC) simulations involving relativistic plasma beams. NCR is caused by spurious coupling between electromagnetic-field modes and multiple beam resonances. This coupling may result from the slow down of poorly-resolved waves due to numerical (grid) dispersion and from aliasing mechanisms. NCR has been studied in the past for finite-difference-based EM-PIC algorithms on regular (structured) meshes with rectangular elements. In this work, we extend the analysis of NCR to finite-element-based EM-PIC algorithms implemented on unstructured meshes. The influence of different mesh element shapes and mesh layouts on NCR is studied. Analytic predictions are compared against results from finite-element-based EM-PIC simulations of relativistic plasma beams on various mesh types. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free