Kinetic dissipation and anisotropic heating in a turbulent collisionless plasma

TL;DR

This study investigates how collisionless plasmas dissipate energy and heat anisotropically at small scales, revealing magnetic field-driven heating mechanisms distinct from traditional fluid models.

Contribution

It demonstrates that in collisionless plasmas, energy dissipates mainly through magnetic fields and protons heat perpendicularly without cyclotron resonance, using hybrid simulations.

Findings

Protons heat preferentially perpendicular to the magnetic field.

Energy dissipation occurs mainly through magnetic field interactions.

Hybrid simulations reveal differences from MHD at small scales.

Abstract

The kinetic evolution of the Orszag-Tang vortex is studied using collisionless hybrid simulations. In the magnetohydrodynamic regime this vortex leads rapidly to broadband turbulence. Significant differences from MHD arise at small scales, where the fluid scale energy dissipates into heat almost exclusively through the magnetic field because the protons are decoupled from the magnetic field. Although cyclotron resonance is absent, the protons heat preferentially in the plane perpendicular to the mean field, as in the corona and solar wind. Effective transport coefficients are calculated.