Influence of injected plasma on oscillations of cathode luminosity in triggered vacuum breakdown

The authors report experiments performed with a triggered vacuum gap in order to investigate how plasma injected into the gap affects the frequency of oscillations in cathode luminosity during vacuum breakdown. The density of injected plasma is varied by changing the parameters of the triggering gap. Light from the main gap is recorded using an ultrafast streak camera. In all cases, streak photographs show oscillations in cathode light with a constant pulse repetition rate of about 5 ns/pulse. The injected plasma does not affect the repetition rate of cathode light pulses. Additional testing of the streak camera indicates that light pulses in a streak trace can be created very easily by electromagnetic interference. It is concluded that cathode light pulses are most likely an artifact associated with the improperly shielded streak camera