Parametric Investigation of the Commutation Performances of a Pseudospark Switch Triggered with a PZT Ceramic

Devices using the pseudospark discharge effect (i.e. the succession of a trigger mechanism, a fast charge multiplication supported by a hollow cathode, and a pulsed superglow discharge) have been used for decades both as high power switches and as electron beam sources. As shown in the literature, the trigger function can be achieved with several technologies. However, the conditions required for triggering reliably the pseudospark switch remains poorly documented. This paper addresses this topic by using a PZT ferroelectric trigger unit in a single-stage helium-filled pseudospark. Experimental conditions within the pseudospark, such as the helium pressure, the anode voltage, and the pulsed trigger voltage are swept to assess their influence on the switch commutation capability and on commutation parameters (delay and jitter). The increase of the trigger voltage is found to improve the success rate of the trigger unit, and significantly reduces both breakdown delay and jitter. On the contrary, anode voltage and helium pressure have little impact on the commutation parameters in the range of investigation. Optical diagnostics, including gated intensified camera imaging and emission spectroscopy, are also use to investigate the predischarge characteristics. The early stages of the discharge are also modeled with particle-in-cell simulations, and a qualitative agreement for the pseudospark trigger requirements and breakdown delay is found between experimental results and simulation.