Electron acceleration and thermalization at magnetotail separatrices

TL;DR

This paper investigates how electrons are accelerated and thermalized during magnetic reconnection in Earth's magnetotail, revealing the role of electrostatic waves in energy redistribution.

Contribution

It provides new insights into electron acceleration mechanisms and wave-particle interactions at magnetotail reconnection separatrices using MMS data.

Findings

Electrons are accelerated to keV energies near the X line.

Electrostatic waves develop into solitary waves that interact with electrons.

Wave-particle interactions thermalize electron beams, converting directed energy into heat.

Abstract

In this study we use the Magnetospheric Multiscale (MMS) mission to investigate the electron acceleration and thermalization occurring along the magnetic reconnection separatrices in the magnetotail. We find that initially cold electron lobe populations are accelerated towards the X line forming beams with energies up to a few keV's, corresponding to a substantial fraction of the electron thermal energy inside the exhaust. The accelerated electron populations are unstable to the formation of electrostatic waves which develop into nonlinear electrostatic solitary waves. The waves' amplitudes are large enough to interact efficiently with a large part of the electron population, including the electron beam. The wave-particle interaction gradually thermalizes the beam, transforming directed drift energy to thermal energy.