The characteristics of vacuum arc with stationary diffuse spot on non-thermionic cathode

The vacuum arc with stationary diffuse spot on the solid cathode from chromium has been studied. The arc current was 30-220 A, cathode temperature 1800-2100 K. The mean current density on the cathode 10-10/sup 2/ A/cm/sup 2/. The part of thermionic current at the cathode was less than 0.1 % from arc current. Observations of cathode surface during arcing with help of a laser monitor did not discover noticeable arc influence on the cathode. The experimental data on the cathode temperatures, the heat flow from plasma to cathode and the evaporation rate of the cathode are presented. The possible mechanisms of the charge transfer on the cathode surface are discussed.