Suppression of collisionless magnetic reconnection in asymmetric current sheets

TL;DR

This paper investigates how asymmetric current sheets suppress collisionless magnetic reconnection, revealing that electron flux slippage and drift dynamics play key roles in the process.

Contribution

It demonstrates that electron flux slippage can facilitate or suppress reconnection depending on the current sheet asymmetry and drift conditions, providing new insights into reconnection suppression mechanisms.

Findings

Slippage between electrons and magnetic flux facilitates reconnection.

Asymmetric current sheets can suppress or enable reconnection depending on drift conditions.

X-line drift is slowed and can be overtaken by faster flux, suppressing reconnection.

Abstract

Using fully kinetic simulations, we study the suppression of asymmetric reconnection in the limit where the diamagnetic drift speed >> Alfven speed and the magnetic shear angle is moderate. We demonstrate that the slippage between electrons and the magnetic flux facilitates reconnection, and can even result in fast reconnection that lacks one of the outflow jets. Through comparing a case where the diamagnetic drift is supported by the temperature gradient with a companion case that has a density gradient instead, we identify a robust suppression mechanism. The drift of the x-line is slowed down locally by the asymmetric nature of the current sheet and the resulting tearing modes, then the x-line is run over and swallowed by the faster-moving following flux.