Design and testing of a multi-triggered spark gap switch for 2-15 kJ plasma focus device

Abstract

Summary form only given, as follows. A multi-channel spark gap switch has been widely used in high current and low inductance pulse forming network to obtain switching of fast rise time and high current pulses. Inductance and resistance of a spark gap switch rapidly decrease with increase of channels and electrode erosion is reduced by lower current density. In this work, an electrically multi-triggered spark gap switch was developed to be used as a multi-channel spark gap switch in a 2-15 kJ plasma focus device with a capacitor of Maxwell No 32169 (capacitance, 32 uF, inductance 65 nH). The geometry of the multi-triggered spark gap switch is similar to an annular-type rail gap switch. The large bodies of dielectric that surround the electrodes were designed to prevent arcing along the exterior of the gap. The dielectric material is translucent polycarbonate which has high Izod impact strength. By using translucent polycarbonate, the breakdown in the gap switch could be visually observed. The main electrodes and trigger are made of stainless steel. The minimum gap spacing in this switch is 7 mm and the trigger is located between two main electrodes. The trigger is similar to the main electrode of the trigatron switch. In parenthesis, five different trigger-pins are located in the main trigger-plate and these are isolated with dielectric material. Therefore, six different trigger signals can be generated with a time difference of a few micro-seconds.