Diagnosing numerical Cherenkov instabilities in relativistic plasma simulations based on general meshes
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.
Keywords
Cite
@article{arxiv.1809.05534,
title = {Diagnosing numerical Cherenkov instabilities in relativistic plasma simulations based on general meshes},
author = {D. -Y. Na and J. L. Nicolini and R. Lee and B. -H. V. Borges and Y. A. Omelchenko and F. L. Teixeira},
journal= {arXiv preprint arXiv:1809.05534},
year = {2019}
}
Comments
31 pages, 20 figures