The Adiabatic Phase Mixing and Heating of Electrons in Buneman Turbulence

TL;DR

This paper investigates how Buneman turbulence causes rapid electron heating through phase mixing and separatrix crossing, using a Hamiltonian formalism to describe electron dynamics during instability saturation.

Contribution

It introduces a Hamiltonian approach to model electron trapping and de-trapping in Buneman turbulence, revealing the irreversibility and heating mechanism of the process.

Findings

Electron temperature increases rapidly during instability saturation.

Electron motion can be modeled with Hamiltonian formalism in the adiabatic limit.

Separatrix crossing leads to irreversible electron energy gain.

Abstract

The nonlinear development of the strong Buneman instability and the associated fast electron heating in thin current layers with $\Omega_e/\omega_{pe} <1$ are explored. Phase mixing of the electrons in wave potential troughs and a rapid increase in temperature are observed during the saturation of the instability. We show that the motion of trapped electrons can be described using a Hamiltonian formalism in the adiabatic approximation. The process of separatrix crossing as electrons are trapped and de-trapped is irreversible and guarantees that the resulting electron energy gain is a true heating process.