Fast Magnetic Reconnection Due to Anisotropic Electron Pressure

TL;DR

This paper identifies a new fast magnetic reconnection regime driven by electron pressure anisotropy, which can dominate over the Hall effect, especially in low plasma beta environments like the solar wind and tokamaks.

Contribution

It introduces a novel reconnection mechanism involving electron pressure anisotropy described by Chew-Goldberger-Low equations, confirmed through fluid simulations.

Findings

Electron pressure anisotropy causes a quadrupole magnetic field structure.

Dispersive waves are generated by the anisotropy.

The mechanism is relevant in low plasma beta plasmas.

Abstract

A new regime of fast magnetic reconnection with an out-of-plane (guide) magnetic field is reported in which the key role is played by an electron pressure anisotropy described by the Chew-Goldberger-Low gyrotropic equations of state in the generalized Ohm's law, which even dominates the Hall term. A description of the physical cause of this behavior is provided and two-dimensional fluid simulations are used to confirm the results. The electron pressure anisotropy causes the out-of-plane magnetic field to develop a quadrupole structure of opposite polarity to the Hall magnetic field and gives rise to dispersive waves. In addition to being important for understanding what causes reconnection to be fast, this mechanism should dominate in plasmas with low plasma beta and a high in-plane plasma beta with electron temperature comparable to or larger than ion temperature, so it could be relevant in the solar wind and some tokamaks.