The use of commercial thyristors in repetitive high voltage switching devices for plasma sources

This paper presents a commercial high voltage thyristor used as a switch allowing a tank capacitor to discharge in a load. In classical high power pulse technology applications the output voltage pulse has to be characterized mainly by its crest value, its rise-time, the period the thyristor is held in the on-state and the fall-time. These parameters are studied as a function of the power circuit and of the trigger circuit. The thyristor presents two behaviours: the main current is either higher or lower than the latching current. The "low current" behaviour is extensively investigated as it allows repetitive operation of the device. Two pulse power applications triggering electrical discharges are presented. Each one necessitates a specific pulsed power supply using series thyristor stacks or Marx structures. The first pulsed source delivers negative pulses with a crest voltage V-oM = -35 kV, a turn on capability of T-r = 90 ns and a repetition rate F = 900 Hz. The second is built using Marx structure and is characterized by V-oM = 60 kV, T-r = 250 ns, F = 900 Hz.