Enrique Bello

PhD Thesis

Study of the turbulent transport in Hall-effect plasma thrusters

Supervisors

Eduardo Ahedo (UC3M)

Abstract

Hall-effect plasma thruster are one of the main electric space-propulsion technologies in the market. However, the plasma physics behind its operation are not perfectly well understood, what explains the lack of predictive models. One of the main open problems in the Hall-discharge plasma physics, after more than 50 years of active research, is the anomalously high cross-field electron transport observed when comparing experiments with theory and simulations. Instabilities and turbulence are inherent to partially magnetized ExB plasmas, such as that of the Hall-thruster discharge. They are known to enhance the cross-field electron transport and are, thus, well-positioned candidates to explain the anomalous transport. The turbulence and instabilities take place under a wide range of wavelengths (from typical thruster size to scales below the electron Larmor radius) and frequencies (from a few kHz to tenths of MHz).  Currently, there exist no agreement in the community about the main instability contributing to anomalous transport. In this thesis, instabilities are investigated using global and local linear stability models with a macroscopic description for the plasma species. Several mechanisms are found to destabilize the discharge: relative drift between charged species, dissipation and gradients in the background plasma. The analysis of scales close and below the electron Larmor radius require a kinetic description for the electrons, that leads to the dispersion relation for the electron-cyclotron drift instability. In addition to the linear stability analyses, a full particle-in-cell model is developed in the context of this thesis in order to analyze instabilities and turbulence in the axial and azimuthal directions.

Project participation

Research Stays

Doctoral Meetings 2021-2022

Doctoral Meetings 2020-2021