Microscopic structure of electromagnetic whistler wave damping by kinetic mechanisms in hot magnetized Vlasov plasmas

TL;DR

This paper uses electromagnetic Vlasov simulations to analyze the kinetic damping mechanisms of whistler waves in hot magnetized plasmas, revealing the interplay of global and resonant electron effects on wave damping and frequency shifts.

Contribution

It provides a detailed kinetic model and simulation analysis of whistler wave damping, highlighting the roles of phase-mixing and resonant electron interactions in hot plasmas.

Findings

Damping involves both global and resonant electron mechanisms.

Finite electron temperature affects wave frequency and damping.

Thermalization and phase-mixing are key to wave damping processes.

Abstract

The kinetic damping mechanism of low frequency transverse perturbations propagating parallel to the magnetic field in a magnetized warm electron plasma is simulated by means of electromagnetic (EM) Vlasov simulations. The short-time-scale damping of the electron magnetohydrodynamic whistler perturbations and underlying physics of finite electron temperature effect on its real frequency are recovered rather deterministically, and analyzed. The damping arises from an interplay between a global (prevailing over entire phase-space) and the more familiar resonant-electron-specific kinetic damping mechanisms, both of which preserve entropy but operate distinctly by leaving their characteristic signatures on an initially coherent finite amplitude modification of the warm electron equilibrium distribution. The net damping results from a deterministic thermalization, or phase-mixing process, largely supplementing the resonant acceleration of electrons at shorter time scales, relevant to short-lived turbulent EM fluctuations. A kinetic model for the evolving initial transverse EM perturbation is presented and applied to signatures of the whistler wave phase-mixing process in simulations.