Extending the detection limit of trace erosion products in ultra-long-lifetime Hall thrusters using a high-sensitivity ICCD image spectra monitoring system

AbstractOptical emission spectroscopy (OES), as a highly sensitive real-time monitoring method, has been widely applied in swift lifetime evaluation of Hall thrusters. However, as the erosion rate of ultra-long-lifetime magnetically shielded Hall thrusters reduced by an order of magnitude, traditional OES becomes insufficient for real-time monitoring. To address this bottleneck, this study proposes a high-sensitivity monitoring strategy utilizing image spectra rather than traditional line spectra. By distinguishing the 2D Gaussian morphology of signal peaks from noise point clouds, a specialized high-dimensional filtering algorithm was developed to extract weak signals from complex backgrounds. The system achieved a 4.9-fold improvement in detection lower limit compared to conventional methods, enabling the reliable extraction of sub-ppm erosion signals. Beyond satisfying the rigorous monitoring requirements of magnetically shielded Hall thrusters, this method demonstrates significant potential for analyzing trace contaminants in general vacuum systems. Furthermore, a multi-spatial-position synchronous spectral measurement technique was developed to characterize the spatial distribution of erosion products, providing experimental validation for erosion transport theory models. This work establishes a robust monitoring system for magnetically shielded Hall thrusters’ erosion characterization, addressing the critical lack of rapid optimization and efficient evaluation methods in the long-life design of next-generation Hall thrusters.