A PULSE TRAIN TRIGGER FOR IGNITRON SWITCHES

The National Electronics NL496 (Size E) Ignitrons, widely used in the RFX Power Supply System, showed the holding (or auxiliary) anode current extinction when subjected to pulse waveforms (from 5 to 500 p) of the main anode current. Experimental and theoretical investigations highlighted the mechanism of the phenomenon, which is related to the geometry of the valve. For this reason, retriggering of the ignitron has been found as general solution to reignite the holding anode current; the prototype of a pulse train trigger circuit has been developed and successfully tested.