New Insights into Dissipation in the Electron Layer During Magnetic Reconnection

TL;DR

This study compares laboratory measurements and simulations of electron dissipation layers during magnetic reconnection, revealing discrepancies in layer thickness and suggesting 3D effects and residual collisions are important for understanding fast reconnection.

Contribution

It provides detailed experimental and simulation comparisons, highlighting the limitations of current 2D collisionless models in explaining electron dissipation.

Findings

Electron layer thickness is 3-5 times larger than predicted by 2D collisionless models.

Collisionless electron nongyrotropic pressure alone cannot account for observed reconnection rates.

3D effects and residual collisions are likely significant in electron-scale dissipation during reconnection.

Abstract

Detailed comparisons are reported between laboratory observations of electron-scale dissipation layers near a reconnecting X-line and direct two-dimensional full-particle simulations. Many experimental features of the electron layers, such as insensitivity to the ion mass, are reproduced by the simulations; the layer thickness, however, is about 3-5 times larger than the predictions. Consequently, the leading candidate 2D mechanism based on collisionless electron nongyrotropic pressure is insufficient to explain the observed reconnection rates. These results suggest that, in addition to the residual collisions, 3D effects play an important role in electron-scale dissipation during fast reconnection.