The current-driven anomalous transports in multi-fluid and kinetic plasma descriptions: A simulation study of anomalous transport levels

TL;DR

This study compares multi-fluid and kinetic plasma models, revealing that multi-fluid simulations exhibit higher anomalous transport levels due to differences in wave-particle interactions and Landau damping effects.

Contribution

It provides a detailed comparison between multi-fluid and kinetic plasma models, highlighting the mechanisms behind differing anomalous transport levels.

Findings

Multi-fluid simulations show stronger current reduction than kinetic simulations.

Landau damping stabilizes plasma in kinetic models when electron drift velocity drops.

Current relaxation halts in kinetic models while electron drift remains high.

Abstract

In most fluid models the generation mechanism and the magnetide of anomalous transport are usually treated as auxiliary terms external to the model description and are free to manipulate, the anomalous transport is indeed a noticeably self-generated effect exhibited in a multi-fluid system. Comparing the current relaxation levels with kinetic Vlasov simulation of the same initial setups, it's found that there is a higher anomalous transport in the multi-fluid plasma, i.e. a stronger current reduction in the multi-fluid simulation than in the kinetic Vlasov simulation for the same setup. To isolate the mechanism that causes the different anomalous transport levels, we hence investigated the detailed wave-particle interaction by using spectrum analysis of the generated waves, combined with a spatial-averaged distributions at different instants. It shows that the Landau damping in kinetic simulation takes a role that stablizes the plasma-drifting system, when the bulk veliocity of electron drifts drop beneath the phase velocity of waves. The current relaxation process stops while the relative drift velocity between electrons is still high.