Matteo Ripoli

Nationality: Italian

PhD Thesis

Stability analysis of magnetized plasma flows for space propulsion

Supervisors

Mario Merino Martinez (UC3M) and Eduardo Ahedo (UC3M)

Abstract

Magnetic Nozzles (MN) are the acceleration device of electrodeless plasma thrusters. While the fundamental physics of MNs has been investigated experimentally and theoretically in the past, there are several topics that remain unclear and require further study. In particular, recent experiments evidence the existence of oscillations and/or instabilities in the plasma flow of these devices, an aspect so far not investigated but of dire importance on the efficiency of the MN as they may drive cross-field electron transport. Preliminary results suggest that these instabilities may fall within the drift wave category, but the exact nature of them remains to be ascertained.

This thesis aims to study plasma fluid instabilities in the MN by analytical and numerical modeling. To this end, a two-fluid model will first be established, and a linear stability analysis will be performed. The model will be gradually extended from an axial magnetoplasma column to a slowly-diverging magnetoplasma flow. Then, a quasi-2D fluid code will be developed to perform a global stability analysis of the MN. Modeling results will be compared against existing laboratory data.

Activities to be carried out include:

Literature review of plasma waves and instabilities in relevant configurations
Derivation of drift dispersion relation for a plasma slab (under different degrees of simplification)
Extension to axisymmetric, slowly-diverging plasma flow
Application of dispersion relation to equilibria flows from simulations and experiments
Development of quasi-2D code to perform a global linear stability analysis of the MN