Experimental data on the initiation of a pseudospark discharge

In connection with the development of a pseudospark switch for copper vapor lasers, several long endurance tests at repetition rates between 50 Hz and 7 kHz have been performed during the past years. These tests give some clues to the basic phenomena that are involved in the current build-up of a pseudospark discharge, especially as concerns the interaction of gas and surface effects. According to these results, current flow is initiated by a glow discharge in such a way that the positive column penetrates into the hollow cathode; forming a virtual anode. When the current reaches a threshold value <100 A, the electric field produced in the cathode fall of the glow discharge is sufficient for the formation of cathode spots in the cathode backspace. The spots act as electron emitters and carry the discharge current up to approximately 1 kA, where large area emission processes at the front side of the cathode might become important