Insights from Collisional-Radiative Models of Neutral and Singly Ionized Xenon in Hall Thrusters

• Published in: Journal of propulsion and power 2022-09, Vol.38 (5), p.866-879
• Main Authors: Chaplin, Vernon H., Johnson, Lee K., Lobbia, Robert B., Konopliv, Mary F., Simka, Timothy, Wirz, Richard E.
• Format: Article
• Language: English
• Subjects: Aerospace engineering; Atoms & subatomic particles; Electron density; Electron energy; Electron impact excitation; Emission analysis; Energy; Hall thrusters; Ion transport; Matrix methods; Plasma; Radiation; Steady state models; Velocity; Xenon
• ISSN: 1533-3876; 0748-4658; 1533-3876
• DOI: 10.2514/1.B38676

Collisional-radiative (CR) models for neutral and singly ionized xenon have been constructed for applications to Hall thruster diagnostics. The models use primarily theoretical electron-impact excitation cross sections calculated using the Dirac B-spline R-matrix method. This paper describes the models’ construction and their validation against heritage CR models and previously published Hall thruster data, and then outlines several applications. The baseline 0D steady-state models are used to investigate electron density dependence in neutral xenon emission line intensity ratios commonly used to measure electron temperature, and also to demonstrate that stepwise ionization through excited states is an important process in Hall thrusters. The models are extended to evaluate impacts of neutral and ion transport on 0D CR model applicability, intrinsic bandwidth limits for time-dependent line intensity measurements, and errors introduced when the plasma is assumed to be optically thin.