A Multigap Multiaperture Pseudospark Switch and Its Performance Analysis for High-Voltage Applications

In this article, the development and switching characterization of a coaxial three-gap demountable multigap multiaperture pseudospark switch (MGMA-PSS) prototype is presented. The investigated MGMA-PSS geometry has three gaps which are separated by two cavity drift space regions. A high dielectric constant ferroelectric-based single plasma trigger unit, located within the hollow cathode of the first gap, is used for effective discharge initiation and subsequent synchronous breakdown of the three gaps of the MGMA-PSS. To guarantee long lifetime with high currents and high hold-off voltages and optimized plasma coupling, kidney-shaped ring slot electrodes with baffles are used. Each of the gaps is designed for a minimum voltage hold-off up to 30 kV, with a total voltage hold-off for the MGMA-PSS of approximately 70 kV. Studies of switching behavior are carried out at different operating conditions, such as operating voltages (5-40 kV), hydrogen gas pressures (10-40 Pa), various trigger configurations, and change of circuit parameters [charging capacitance (36, 200, and 380 nF), load resistance (2.7 and 8.3 Omega)]. The short time-scale analysis of the breakdown voltage waveform shows steps in the voltage fall at low gas pressure (< 20 Pa) and low hold-off voltages (< 15 kV), which indicates a too-long time delay in plasma formation and coupling within the drift regions. This effect could not be observed at higher voltages (>= 15 kV) and gas pressure (>= 20 Pa). The overall performance of the three-gap prototype PSS has been analyzed in terms of hold-off voltage, fall time, current rise time, peak current, delay time, and related parameters.