'Triggerless' triggering of vacuum arcs

Vacuum arcs can be initiated without external means of power enhancement at the cathode surface (by using a high-voltage trigger, laser triggering, and so on). Are initiation by simply applying the relatively low voltage of the are power supply is possible if the cathode-anode-separating insulator is coated with a conducting layer and the current at the layer-cathode interface is concentrated at one or a few contact points. The local power density at these contact points can exceed 10(16) W m(-3) which is sufficient for plasma production and thus are initiation. This 'triggerless' principle has been tested successfully with a large number of cathode materials. One extended test was performed with titanium and more than 10(6) pulsed vacuum are initiations have been obtained.