Influence of Continuous Discharge on Erosion-Corrosion of Hollow Cathode for Spacecraft Propulsion

Herein, we experimentally addressed the erosion-corrosion of hollow cathode for spacecraft propulsion.The impact of the continuous discharge, for over 15, 000 h under the rated operating conditions, on surface erosion-corrosion and performance of lanthanum hexaboride (LaB₆) hollow cathode was investigated with scanning electron microscopy, energy dispersive spectroscopy and lab-built test platform in destructive testing.The results show that the localized erosion-corrosion damages, originated from the continuous discharge, only weakly affected the key operating characteristics of the hollow cathode.To be specific, continuously sputtered by high energy ions, the top conical surface was seriously eroded and corroded, accompanied by evaporation and downward accumulation of tungsten and by slightly narrowing the cathode orifice.Moreover, the strong erosion-corrosion deformed and damaged the LaB₆ emitter and changed the contents distributions on the emitter surface.