Investigation of the collisionless plasmoid instability based on gyrofluid and gyrokinetic integrated approach

TL;DR

This paper compares gyrofluid and gyrokinetic models to analyze collisionless plasmoid instability in current sheets with finite electron beta, revealing that finite beta enhances plasmoid growth and gyrofluid models effectively predict this behavior.

Contribution

It introduces a detailed comparison between gyrofluid and gyrokinetic simulations to study the effects of finite electron beta on collisionless plasmoid instability.

Findings

Gyrofluid models accurately predict plasmoid instability observed in gyrokinetic simulations.

Finite electron beta promotes plasmoid growth in collisionless plasmas.

The closure method in gyrofluid models influences energy variation during instability.

Abstract

In this work, the development of two-dimensional current sheets with respect to tearing-modes, in collisionless plasmas with a strong guide field, is analysed. During their non-linear evolution, these thin current sheets can become unstable to the formation of plasmoids, which allows the magnetic reconnection process to reach high reconnection rates. We carry out a detailed study of the impact of a finite $\beta_e$, which also implies finite electron Larmor radius effects, on the collisionless plasmoid instability. This study is conducted through a comparison of gyrofluid and gyrokinetic simulations. The comparison shows in general a good capability of the gyrofluid models in predicting the plasmoid instability observed with gyrokinetic simulations. We show that the effects of $\beta_e$ promotes the plasmoid growth. The impact of the closure applied during the derivation of the gyrofluid model is also studied through the comparison of the energy variation.