Turbulent Thermal Equilibration of Collisionless Magnetospheric Plasmas

TL;DR

This paper investigates how turbulence in collisionless magnetospheric plasmas leads to thermal equilibration between electrons and ions, highlighting the roles of magnetic curvature, density gradients, and nonlinear gyrokinetic effects.

Contribution

It demonstrates that turbulence driven by magnetic curvature and density gradients causes temperature equilibration between species without collisions, supported by stability analysis and gyrokinetic simulations.

Findings

Turbulence tends to equalize electron and ion temperatures.

Destabilization depends on species' temperatures and roles.

Simulations confirm energy transfer leading to thermal equilibrium.

Abstract

How thermal equilibrium is determined in a weakly collisional plasma is a fundamental question in plasma physics. This letter shows that the turbulence driven by the magnetic curvature and density gradient tends to equilibrate the temperature between species without collisions in a magnetospheric plasma. The classical stability analysis in terms of energetic consideration reveals the interchangeable roles of electrons and ions for destabilization depending on their temperatures. Nonlinear gyrokinetic simulations confirm that the higher-temperature destabilizing species gives free energy to heat the other species to achieve the equal temperature state.