A cancellation problem in hybrid particle-in-cell schemes due to finite particle size

Journal Article · 14 July 2020 · Journal of Computational Physics

DOI: https://doi.org/10.1016/j.jcp.2020.109705 · OSTI ID:1641558

Stanier, Adam John  ^[1]; Chacon, Luis  ^[1]; Le, Ari Yitzchak  ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

The quasi-neutral hybrid particle-in-cell algorithm with kinetic ions and fluid electrons is a popular model to study multi-scale problems in laboratory, space, and astrophysical plasmas. Here, it is shown that the different spatial discretizations of ions as finite-spatial-size particles and electrons as a grid-based fluid can lead to significant numerical wave dispersion errors in the long wavelength limit (kd_i«1, where k is the wavenumber and di is the ion skin-depth). The problem occurs when high-order particle-grid interpolations, or grid-based smoothing, spreads the electric field experienced by the ions across multiple spatial cells and leads to inexact cancellation of electric field terms in the total (ion + electron) momentum equation. Practical requirements on the mesh spacing Δx/d_i are suggested to bound these errors from above. The accuracy impact of not respecting these resolution constraints is shown for a non-linear shock problem.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1641558
• Report Number(s): LA-UR-19-32264
• Journal Information: Journal of Computational Physics, Journal Name: Journal of Computational Physics Vol. 420; ISSN 0021-9991
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English