Gyrokinetic simulations of electric current generation in ion temperature gradient driven turbulence

TL;DR

This paper uses gyrokinetic simulations to explore how turbulence driven by ion temperature gradients generates electric currents, revealing detailed mechanisms and structures near rational surfaces.

Contribution

It introduces a simulation approach that captures fine-scale turbulence-induced currents and their relation to Reynolds stress divergence in collisionless plasmas.

Findings

Turbulence-driven currents vary in space and time.

Reynolds stress divergence significantly influences current generation.

Large local currents occur near rational surfaces.

Abstract

Gyrokinetic simulations in the collisionless limit demonstrate the physical mechanisms and the amplitude of the current driven by turbulence. Simulation results show the spatio-temporal variation of the turbulence driven current and its connection to the divergence of the Reynolds stress and the turbulence acceleration. Fine structures (a few ion Larmor radii) of the turbulence induced current are observed near the rational surfaces with the arbitrary wavelength solver of the quasi-neutrality equation. The divergence of the Reynolds stress plays a major role in the generation of these fine structures. The so-called "spontaneous" current is featured with large local magnitude near the rational surfaces.