Development of Cathode Spots on the Surface of a Beryllium

Presented here for the first time are the results of experimental investigations of the cathode spot dynamics at the surface of a beryllium cathode in an arc discharge at a current of 60 v A in a high vacuum. A high-speed electron-recording technique for measurements of the luminescence from cathode spots with a time resolution of about 100 v ns revealed two types of spots, differing greatly in velocity at which they move along the cathode surface. It is established that cathode spots of the first type, which arise at a beryllium surface with an oxide film, move at velocities up to 500 v m/s, while the velocity of cathode spots of the second type, which arise at a pure beryllium surface, is lower by two orders of magnitude.