Electron Heating by Debye-Scale Turbulence in Guide-Field Reconnection

TL;DR

This paper demonstrates that Debye-scale electrostatic turbulence, including Buneman waves and beam modes, significantly contributes to electron heating during guide-field magnetic reconnection, as observed by MMS.

Contribution

It provides the first observational evidence that electrostatic turbulence at Debye scales facilitates electron thermalization in guide-field reconnection.

Findings

Debye-scale turbulence develops within the diffusion region.

Buneman waves and beam modes cause rapid electron heating.

Turbulence plays a key role in energy transfer during reconnection.

Abstract

We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with moderate guide field using observations by the Magnetospheric Multiscale (MMS) mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating.