The effect of pre-ionization on gas puff Z-pinch experiments on a linear transformer driver

Z-pinches are intense X-ray and neutron sources [1]. Neutral gas used for gas puff Z-pinch experiments is ionized when the voltage applied across the A-K gap exceeds some minimum value given by the Paschen curve for the experimental configuration. This type of ionization is statistical, resulting in shot-to-shot variation in current. Externally pre-ionizing the gas puff is presumed to improve experimental reproducibility by providing an established current path [1]. Pre-ionization has also been shown to increase compression ratio, decrease instability and increase X-ray yield [2,3]. The CESZAR LTD (500kA, 150ns) experimental platform at UCSD has been fitted with a custom-built preionizer. Ne hollow gas puff was imploded on a solid-fill D₂ target. Here we present a pre-ionizer design for the CESZAR current driver and report the effect of preionization on experimental reproducibility, compression ratio, stability and X-ray as well as neutron yields.