Systematic 2.5 D resistive MHD simulations with ambipolar diffusion and Hall effect for fast magnetic reconnection

TL;DR

This paper uses 2.5D resistive MHD simulations to demonstrate that ambipolar diffusion and the Hall effect significantly enhance magnetic reconnection rates and energy conversion efficiency.

Contribution

It is the first to investigate the combined effects of ambipolar diffusion and the Hall effect on magnetic reconnection in a systematic 2.5D simulation framework.

Findings

Ambipolar diffusion increases reconnected flux by up to 75%.

Hall effect combined with ambipolar diffusion boosts flux by 143%.

Reconnection rates reach ~0.1 with combined effects, indicating faster reconnection.

Abstract

In this work, we explore the possibility of the Hall effect and ambipolar diffusion as a mechanism for fast reconnection. The reconnected flux of our resistive and resistive+Hall simulations replicates the GEM results. Furthermore, we investigate, for the first time, the effect of ambipolar diffusion in the GEM. The reconnected flux of the resistive+ambipolar and resistive+Hall+ambipolar simulations showed increases of up to 75\% and 143\%, respectively, compared to the resistive and resistive+Hall simulations, showing that ambipolar diffusion contributes significantly to the reconnected flux. Our second scenario has a magnetic Harris field without perturbations but with an out-of-plane component, known as a guide field. We found that the reconnection rate increased faster with ambipolar diffusion, reaching values close to 0.1 for the resistive+Hall+ambipolar simulation followed by the resistive+Hall. These two simulations achieved the highest kinetic energy, implying more efficient energy conversion during reconnection.