Cross-field chaotic transport of electrons by ExB electron drift instability in Hall thruster

TL;DR

This paper models the chaotic electron transport in Hall thrusters caused by wave-particle interactions with electrostatic instabilities, explaining increased electron temperature and axial transport consistent with experiments.

Contribution

It introduces a model linking electrostatic wave interactions to chaotic electron dynamics and anomalous transport in Hall thrusters, providing insights into underlying mechanisms.

Findings

Electrons gain energy from electrostatic waves, increasing perpendicular temperature.

Wave-particle interactions induce axial electron velocities matching experimental data.

Chaotic dynamics explain the anomalous cross-field electron transport.

Abstract

A model calculation is presented to characterize the anomalous cross-field transport of electrons in a Hall thruster geometry. The anomalous nature of the transport is attributed to the chaotic dynamics of the electrons arising from their interaction with fluctuating unstable electrostatic fields of the electron cyclotron drift instability that is endemic in these devices. Electrons gain energy from these background waves leading to a significant increase in their temperature along the perpendicular direction $T_\perp / T_\parallel \sim 4$ and an enhanced cross-field electron transport along the thruster axial direction. It is shown that the wave-particle interaction induces a mean velocity of the electrons along the axial direction, which is of the same order of magnitude as seen in experimental observations.