Special Features of the Discharge Formation in the Trigger Unit Based on Breakdown Over the Semiconductor Surface in Sea
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Russian Physics Journal, Vol. 63, No. 5, September, 2020 (Russian Original No. 5, May, 2020)
PLASMA PHYSICS SPECIAL FEATURES OF THE DISCHARGE FORMATION IN THE TRIGGER UNIT BASED ON BREAKDOWN OVER THE SEMICONDUCTOR SURFACE IN SEALED-OFF COLD-CATHODE THYRATRON N. V. Landl, Yu. D. Korolev, G. A. Argunov, V. G. Geyman, O. B. Frants, and A. V. Bolotov
UDC 537.525
The results of investigation of pulsed discharge in the trigger unit based on breakdown over the semiconductor surface in sealed-off cold-cathode thyratrons TDI1-50k/50 are presented. A method for estimation of surface discharge currents is proposed. Based on the data on current distribution between the trigger unit electrodes, the mechanisms of discharge formation in the trigger unit are revealed. Data on delay times and jitter in delay times to ignition of hollow-anode arc discharge in the trigger unit and to breakdown in the thyratron main gap were obtained. It is shown that with the increase of the semiconductor resistance delay times, the jitter also increases. The trigger circuit, which provides the jitter in delay times to breakdown in the thyratron main gap within 10 ns is proposed. Keywords: cold-cathode thyratron, surface discharge, hollow-anode arc discharge.
INTRODUCTION Nowadays switching devices based on high-current low-pressure hollow-cathode pulsed gas discharges (the socalled pseudo-spark switches) [1–10] are wisely used. The design of the electrode system of the switch itself resembles the design of the classical hydrogen heated-cathode thyratron. However, the heated cathode is absent in devices of this type. The main high-voltage gap of the thyratron is formed by a hollow or flat anode and a hollow cathode. The range of working gas pressure in the switch corresponds to the left branch of the Paschen curve. Under these conditions, unlike the high-pressure discharges [11–13], a significant pre-breakdown current from the main cathode cavity to the main thyratron gap is required both for self-breakdown and forced triggering of the switch [14–17]. In the case of forced triggering, this current is provided with a special trigger unit of the switch which is usually located in the main cathode cavity [3, 10, 18–21]. Generally, any trigger unit should generate high-density plasma in the main cathode cavity at a preset time. For this purpose, the voltage pulse with amplitude of 2–8 kV is applied to one of the electrodes of the trigger unit. As a result, the trigger discharge plasma with current of 20–100 A is generated in the main cathode cavity. The electrons from the plasma surface are extracted in the main thyratron gap and initiate a discharge by the mechanism described in [1, 22].
Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia, e-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 90–98, May, 2020. Original a
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