Development and Validation of a Collisional Radiative Model for Neutral Xenon in a Hall Effect Thruster

A neutral Xe collisional radiative model based on the 6s and 6p levels was developed and validated against other models available in the literature and Langmuir probe measurements.

The model solves the non-linear steady-state balance equations of the 6s and 6p levels of Xe considering electron impact excitation, spontaneous emission as well as absorption based on Mewe approximation. Synthetic spectra are generated from the calculated densities of the excited species at steady state, which are then compared with experimental spectra to estimate the plasma parameters, with an emphasis on the electron temperature and electron density.

Optical emission measurements were conducted on a mid-power Hall effect thruster for different voltages at the anode and different Xe injection flows, allowing to scan of the plume along three axes: axial, lateral, and radial. An optimization strategy based on 15 neutral lines was used to predict the electron temperature from the collected spectra.

The developed model successfully reproduced the expected trends in electron temperature and electron density. Comparison between the LP and optical emission spectroscopy measurements demonstrated a high level of agreement between the two methods. Additionally, a comparison between temperature profiles obtained from Particle-in-Cell simulations and the predicted results yielded a favorable agreement in terms of trends and order of magnitude.