Special Features of Parasitic Current Formation in a Sealed-Off Cold-Cathode Thyratron with Trigger Unit Based On an Auxiliary Glow Discharge

Results of investigation of the glow discharge with hollow cathode and ring anode in the trigger unit of a coldcathode thyratron TPI1-10k/50 are presented. A specific feature of the discharge sustainment is that a highly emissive tablet containing cesium carbonate is placed in the cathode cavity. The current-voltage characteristics of the discharge in the trigger unit are obtained for different tablet compositions together with the measured parasitic current to the main cathode cavity. Stepwise transitions to the regime with decreased discharge burning voltage accompanied by an increase in the parasitic current are observed. A model of current sustainment in a hollow-cathode glow discharge is used to interpret the characteristics obtained. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only the ion bombardment of the cathode, but also the emission current from an external source. Based on estimations of the discharge parameters in the trigger unit, a reason for a parasitic current increase is revealed.