Development of a Telemicroscopy Diagnostic Apparatus and Erosion Modelling in Hall Effect Thrusters

A new diagnostic apparatus and a numerical code have been developed by Alta Spa to tackle the problem of Hall Effect Thruster erosion. The diagnostic system consists of a couple of cameras that provide optical measurements of the HET channel, revealing how its shape changes in time when the thruster is firing. Besides, the diagnostic system has been designed to be as versatile as possible and can be employed also for measuring the erosion of ion engine grids with minor modifications. The numerical code is based on a Monte Carlo simulation of the ion sputtering phenomenon inside the acceleration channel. The code has been validated using existing data and it turns out to be a valuable tool not only for predicting HET erosion, but also to investigate possible solutions for erosion reduction (changes in geometry or thruster operational parameters). Of course, the future development of the numerical code is tightly connected with the completion of the diagnostic apparatus, since further comparisons between theoretical predictions and experimental data are necessary for a full validation of the erosion model.