Current Sheets and Collisionless Damping in Kinetic Plasma Turbulence

TL;DR

This study investigates how current sheets form and dissipate at electron scales in kinetic plasma turbulence, highlighting the dominant role of collisionless damping over Ohmic dissipation in plasma heating.

Contribution

It provides the first detailed analysis of current sheet formation and dissipation mechanisms at electron scales in 3D kinetic turbulence simulations, emphasizing collisionless damping processes.

Findings

Current sheets form self-consistently from wave-driven turbulence.

Electron heating correlates with current sheet filling fraction.

Collisionless damping via Landau resonance accounts for plasma heating.

Abstract

We present the first study of the formation and dissipation of current sheets at electron scales in a wave-driven, weakly collisional, 3D kinetic turbulence simulation. We investigate the relative importance of dissipation associated with collisionless damping via resonant wave-particle interactions versus dissipation in small-scale current sheets in weakly collisional plasma turbulence. Current sheets form self-consistently from the wave-driven turbulence, and their filling fraction is well correlated to the electron heating rate. However, the weakly collisional nature of the simulation necessarily implies that the current sheets are not significantly dissipated via Ohmic dissipation. Rather, collisionless damping via the Landau resonance with the electrons is sufficient to account for the measured heating as a function of scale in the simulation, without the need for significant Ohmic dissipation. This finding suggests the possibility that the dissipation of the current sheets is governed by resonant wave-particle interactions and that the locations of current sheets correspond spatially to regions of enhanced heating.