Three-Dimensional Stability of Current Sheets Supported by Electron Pressure Anisotropy

TL;DR

This study uses 3D kinetic simulations to analyze the stability of electron current sheets supported by pressure anisotropy, revealing an electromagnetic instability that does not disrupt the overall structure.

Contribution

It demonstrates the stability of extended electron current sheets supported by pressure anisotropy in 3D reconnection, including the identification of an electromagnetic instability.

Findings

Electron current sheets are supported by pressure anisotropy with parallel pressure larger than perpendicular.

An electromagnetic instability driven by pressure anisotropy exists in 3D reconnection.

Extended electron current layers remain stable despite small-scale fluctuations.

Abstract

The stability of electron current sheets embedded within the reconnection exhaust is studied with a 3D fully kinetic particle-in-cell simulation. The electron current layers studied here form self-consistently in a reconnection regime with a moderate guide field, are supported by electron pressure anisotropy with the pressure component parallel to the magnetic field direction larger than the perpendicular components, and extend well beyond electron kinetic scales. In 3D, in addition to drift instabilities common to nearly all reconnection exhausts, the regime considered also exhibits an electromagnetic instability driven by the electron pressure anisotropy. While the fluctuations modulate the current density on small scales, they do not break apart the general structure of the extended electron current layers. The elongated current sheets should therefore persist long enough to be observed both in space observations and in laboratory experiments.