The inner structure of collisionless magnetic reconnection: The electron-frame dissipation measure and Hall fields

TL;DR

This paper investigates the detailed electron-scale structures and dissipation mechanisms in collisionless magnetic reconnection using PIC simulations, emphasizing the role of the electron-frame dissipation measure and Hall fields.

Contribution

It introduces the application of the electron-frame dissipation measure to electron-scale reconnection structures and highlights the importance of electron physics and the electron-ion mass ratio.

Findings

The dissipation region size depends on the electron-ion mass ratio.

A narrow electron jet extends until reaching an electron shock.

Electron heating at the shock correlates with magnetic cavity signatures.

Abstract

It was recently proposed that the electron-frame dissipation measure, the energy transfer from the electromagnetic field to plasmas in the electron's rest frame, identifies the dissipation region of collisionless magnetic reconnection [Zenitani et al. Phys. Rev. Lett. 106, 195003 (2011)]. The measure is further applied to the electron-scale structures of antiparallel reconnection, by using two-dimensional particle-in-cell (PIC) simulations. The size of the central dissipation region is controlled by the electron-ion mass ratio, suggesting that electron physics is essential. A narrow electron jet extends along the outflow direction until it reaches an electron shock. The jet region appears to be anti-dissipative. At the shock, electron heating is relevant to a magnetic cavity signature. The results are summarized to a unified picture of the single dissipation region in a Hall magnetic geometry.