Transient Analysis of MGMC Spark Gap Switches for Improved Performance in Pulse Power Systems

This paper deals with detailed investigations on the switching behaviour of planar Multi-gap, multichannel (MGMC) spark gap switches that influence their performance in pulse power systems for generation of high magnitude (≥100 kA), fast-rising (≤1 μs) current pulses. The switching behaviour of these switches were studied using a transient equivalent circuit model developed for a 5-gap, planar, air-operated MGMC switch. The coupling parameters between the various switch components were determined using 3-D Electrostatic FEM simulation of the switch geometry using COMSOL Multiphysics 6.0®. Effect of position of trigger electrode on the overall switching performance was studied. Additionally, the effect of adjacent ground plate on the coupling parameters of the switch and the effect on its overall switching behaviour was studied in detail as part of this analysis. Studies reveal that application of negative-polarity trigger pulse on intermediate electrodes just adjacent to the high-voltage (HV) or ground electrodes result in maximum over-volting, thereby causing faster closing time and lesser switching jitter. Also, the incorporation of an adjacent ground plate reduces the overall “sensitivity” of the switch electrodes to the trigger pulse, thereby resulting in much greater over-volting. Thus, the transient analysis of planar MGMC spark gap switches using equivalent circuit model provide important insight into the switching behaviour of these switches which can be utilized to achieve faster rise-time, low-jitter and fast closing times.