Erosion Phenomena on Contaminated Cathodes Caused by Electrical Discharges in Ultra High Vacuum

Self-limiting discharges occur on contaminated cathodes in UHV without any contribution of the anode. They propagate over the cathode surface with velocities ≥ 5.104 m/s, preferentially along grain boundaries. From these observations an analogy is suggested between micro-discharges in high voltage gaps and are spots with weak erosion.