The experimental investigation of a charged particle flows in a submicrosecond vacuum arc at a threshold current

A time dependence of in generation during a lifetime of a single cathode spot is of a great importance. To obtain such a dependence it is necessary to investigated vacuum discharge at a threshold current with small size electrode setup. Vacuum arc was feed by capacitor with restrictive resistor. After arc ignition the arc current decreases in time of 300-500ns up to threshold current. When threshold current was achieved there was only single cathode spot operating in a vacuum arc. A small discharge setup was used to obtain nanosecond time resolution on the ion flow measurement. Cathode-anode gap and anode - collector gap was established as 0.1mm. The average time of fly of ions from cathode spot to the collector can be estimated as 10ns. The estimated lifetime of cathode spot on a molybdenum cathode is 20-50ns. Thus the electrode setup built at the present experiments can be used to obtain ion generation dependence during a single cathode spot lifetime. The electron flow time dependence was obtained too. The results obtained make it possible to connect charged particle flow fluctuations with cathode spot life cycle.