TRIGGERLESS TRIGGERING OF VACUUM ARCS

Vacuum arcs can be initiated without external means of power enhanceme nt at the cathode surface (by using a high-voltage trigger, laser trig gering, and so on). Are initiation by simply applying the relatively l ow voltage of the are power supply is possible if the cathode-anode-se parating insulator is coated with a conducting layer and the current a t 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 ini tiation. This 'triggerless' principle has been tested successfully wit h 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.