Suppression of phase mixing in drift-kinetic plasma turbulence

TL;DR

This paper demonstrates that in turbulent drift-kinetic plasmas, anti-phase-mixing modes effectively cancel phase mixing, reducing Landau damping and isolating fluid moments from higher moments, especially in low-collisionality conditions.

Contribution

It reveals that stochastic plasma echoes induce anti-phase-mixing modes that suppress phase mixing, challenging traditional views on Landau damping in turbulence.

Findings

Phase mixing transfer is nearly canceled by anti-phase-mixing modes.

Fluid moments are energetically isolated from higher moments.

Phase mixing becomes ineffective as a dissipation mechanism in low-collisionality plasmas.

Abstract

Transfer of free energy from large to small velocity-space scales by phase mixing leads to Landau damping in a linear plasma. In a turbulent drift-kinetic plasma, this transfer is statistically nearly canceled by an inverse transfer from small to large velocity-space scales due to "anti-phase-mixing" modes excited by a stochastic form of plasma echo. Fluid moments (density, velocity, temperature) are thus approximately energetically isolated from the higher moments of the distribution function, so phase mixing is ineffective as a dissipation mechanism when the plasma collisionality is small.