Gyrofluid simulations of collisionless reconnection in the presence of diamagnetic effects

TL;DR

This paper uses gyrofluid simulations to study how ion Larmor radius and diamagnetic effects influence collisionless magnetic reconnection, revealing impacts on growth rates, island propagation, and island width.

Contribution

It introduces a Hamiltonian gyrofluid model to analyze the nonlinear effects of ion diamagnetic effects on magnetic reconnection.

Findings

Ion diamagnetic effects decrease growth rate of dominant mode

Higher ion temperature causes magnetic islands to propagate in drift direction

Diamagnetic effects reduce the final width of magnetic islands

Abstract

The effects of the ion Larmor radius on magnetic reconnection are investigated by means of numerical simulations, with a Hamiltonian gyrofluid model. In the linear regime, it is found that ion diamagnetic effects decrease the growth rate of the dominant mode. Increasing ion temperature tends to make the magnetic islands propagate in the ion diamagnetic drift direction. In the nonlinear regime, diamagnetic effects reduce the final width of the island. Unlike the electron density, the guiding center density does not tend to distribute along separatrices and at high ion temperature, the electrostatic potential exhibits the superposition of a small scale structure, related to the electron density, and a large scale structure, related to the ion guiding-center density.