Method for an In-situ Diagnostic for Inner Pole Erosion of a Magnetically Shielded Hall Thruster

Abstract

Erosion in Hall-effect thrusters poses a critical challenge to propulsion efficiency and mission longevity. While erosion is not a new phenomenon for electrical propulsion devices, recent research has identified inner pole erosion as the current primary driver for mission length limitations. This study investigates sensor integration and resistance-based measurement techniques to quantify erosion at the inner pole. An unwired sensor was exposed to 600W (300V, 2A) plasma conditions for two hours, resulting in 3 μm of erosion, calculated from manual resistance measurements. A fully integrated in-situ sensor was exposed to 225W (90V, 2.5A) conditions for one hour and experienced 3-5 μm of erosion, which was calculated from remote measurement data. Sputter yield modeling and experimental erosion rates aligned well with existing literature, while erosion rate modeling underpredicted actual erosion rates, consistent with prior findings. These results support the viability of accelerated, in-situ diagnostics for erosion monitoring at the inner pole. Future work is recommended to improve integration techniques and modeling fidelity.