Optimization of the High Energy Switches for Synchronization of Multiple Plasma Focus Devices

Abstract

Dense Plasma Focus (DPF) devices have been synchronized by optimizing the parameters of high energy spark-gap switches and triggering mechanism. DPF is an intensive source of radiation with large number of applications in plasma physics and material engineering. A three electrode trigatron type spark-gap (controlled switch) is chosen for optimization to achieve the jitter that would be less than radiation emission time of DPF devices. A comparative study of static breakdown voltage (SBV) of spark-gap switch has been done for various gases, e.g., Ar, N₂, SF₆, and NArO (a mixture of O₂, Ar, and N₂). Experimental data shows that SBV is directly proportional to pressure for a fix gap between the two electrodes of spark-gap switch. SF₆ has the highest while Ar has the lowest SBV. The SBV of NArO and N₂ are almost equal because NArO has N₂ as its major component. NArO is found to be the most appropriate gas as it improves the recovery rate due to O₂ content in NArO mixture for repetitive operation of DPF. A circuit is set up to trigger two identical spark-gaps filled with NArO. Two different trigger schemes, a pulse transformer and a two stage Marx bank are used. Marx bank, due to its superior pulse characteristics, successfully triggered both the spark-gaps for all shots. The average jitter of two DPF devices is 26 ns with a standard deviation of 11 ns for multiple shots without any misfire.