Dynamics of cathode spots on the beryllium in vacuum arc discharges

Two types of cathode spots, differing greatly in velocity at which they move along the cathode surface of a beryllium at a current of 60 A in a high vacuum arc discharge were discovered Cathode spots of the first type, which arise at a beryllium surface with an oxide film, move at velocities up to 500 m/s, while the velocity of cathode spots of the second type, which arise at a pure beryllium surface, is up to 5 m/s.