Note: Possibilities of detecting the trace-level erosion products from an electric propulsion hollow cathode plasma source by the method of time-of-flight mass spectrometry.

A hollow cathode produces electrons which neutralize ions from electric propulsion thrusters. After hundreds to thousands of hours of operation in space, the cathode materials can be significantly eroded due to ion bombardment. As a result, the electric propulsion system performance will be obviously changed or even fail.