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

Author(s)

Na, D-Y ^{[1, 2]} ; Nicolini, J. L. ^{[1, 2]} ; Lee, R. ^{[1, 2]} ; Borges, V, B-H ; Omelchenko, Y. A. ^[3] ; Teixeira, F. L. ^{[1, 2]}

Affiliation

^[1] Ohio State Univ, Dept Elect & Comp Engn, Columbus, OH 43212 - USA

^[2] Ohio State Univ, Electrosci Lab, Columbus, OH 43212 - USA

^[3] Trinum Res Inc, San Diego, CA 92126 - USA

• Document type: Journal article
• Source: Journal of Computational Physics; v. 402, FEB 1 2020.
• Web of Science Citations: 0

Abstract

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. (AU)

• FAPESP's process: 15/50268-5 - Novel metamaterials for rf/microwave and optical applications
• Grantee: Ben-Hur Viana Borges
• Support Opportunities: Regular Research Grants