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

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.