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Title: Noise-induced magnetic field saturation in kinetic simulations
Monte Carlo methods are often employed to numerically integrate kinetic equations, such as the particle-in-cell method for the plasma kinetic equation, but these methods suffer from the introduction of counting noise to the solution. We report on a cautionary tale of counting noise modifying the nonlinear saturation of kinetic instabilities driven by unstable beams of plasma. We find a saturated magnetic field in under-resolved particle-in-cell simulations due to the sampling error in the current density. The noise-induced magnetic field is anomalous, as the magnetic field damps away in continuum kinetic and increased particle count particle-in-cell simulations. This modification of the saturated state has implications for a broad array of astrophysical phenomena beyond the simple plasma system considered here, and it stresses the care that must be taken when using particle methods for kinetic equations.
Authors:
; ; ; ;
Award ID(s):
1804048
Publication Date:
NSF-PAR ID:
10204592
Journal Name:
Journal of Plasma Physics
Volume:
86
Issue:
4
ISSN:
0022-3778
Sponsoring Org:
National Science Foundation
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