Development of Real-time Erosion Monitoring System for Hall Thrusters by Cavity Ring-Down Spectroscopy

Sputter monitoring system using continuous-wave cavity ring-down spectroscopy (cw-CRDS) was built for both lifetime assessment and contamination effects in Hall thrusters. We have performed measurements of sputtered manganese atoms from acceleration channel wall (stainless steel 316) in an anode layer type Hall thruster. The measurement strategy is based upon detection of manganese atoms via an absorption line from ground state at a wavelength of 403.076 nm. The path-integrated number density is 1.4 0.3 10 m at a discharge voltage of 200 V and an argon mass flow rate of 70 sccm. The number density is proportional to the discharge voltage, as expected. The number density and mass-loss have a relatively linear dependence. These results show the validity of the erosion sensor for Hall thruster lifetime estimation.

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