Iñaki Fernandez Tena

PhD Thesis

Hybrid particle-fluid plasma modeling of Hall effect thrusters and analisys of non-conventional configurations

Supervisors

Jiewei Zhou Zhu (UC3M), co-supervisor, Adrián Dominguez Vázquez (UMA)

Abstract

The work of this thesis focuses on the study of plasma discharge in high-power Hall effect thrusters (HETs), ranging from 20 to 100 kW. In particular, the aim is to address the design and analysis of multi-channel prototypes, a non-conventional configuration that is currently in the experimental phase and is of great interest for future missions due to its versatility in operating over a wide power range and its optimal power-to-weight ratio. A simulation code will be developed, implementing a hybrid plasma transport model that will use a fluid model for the electron population and a kinetic particle model for the heavy species (ions and neutrals).
The starting point will be HYPHEN, an already existing and well-established code, although limited to the study of conventional configurations mainly due to the use of a magnetic grid in the electron fluid model. This unstructured grid, although it limits the numerical diffusion of anisotropic electrons, requires an ad-hoc process for its generation and complicates the analysis of complex and larger geometries, which demand greater control over the number and quality of the grid cells to optimize computation times and limit interpolation errors. Therefore, a structured cylindrical grid will be implemented, possible numerical issues will be studied, and algorithms will be proposed to solve them.
Once the code is developed, several studies will be carried out. First, results of the discharge with the magnetic and cylindrical grids will be compared. This will allow, on the one hand, the evaluation of numerical errors associated with interpolation and the reconstruction of boundary variables, as well as the comparison of computation times, which will reveal possible algorithmic improvements. On the other hand, the comparison will also allow for the evaluation of numerical diffusion errors in the treatment of magnetized electrons. Second, starting from virtual prototypes designed based on literature references, key aspects of the plasma discharge physics and the operation of these prototypes will be studied, such as the effect of magnetic topology, plasma interaction between channels, operation with alternate channels, cathode coupling with multiple channels, and the issue of current neutralization in the plume. The lifetime (thermal loads and erosion) and performance (losses and efficiencies) will also be analyzed over a wide operating range with various propellants.

Doctoral Meetings

2024 – 2025

Poster