Behavior of the gas-puff z-pinch plasma during the initial phase of discharge in IPP method

Previous gas-puff z-pinch experiments in our study showed that spatial stability of hot spots in radial direction was obtained by using an inductive pulsed power generator. However, it was confirmed that the injected gas was expanded to radial direction during initial phase of discharge. Therefore it was thought that the compressing process and z-pinch characteristics were influenced by the shape of the injected gas column. In this study, pinching phenomenon during initial phase of discharge was observed by changing the gap length and delay time which was defined as a time from gas injection to discharge onset. Framing photographs of initial compressing phase of the z-pinch plasma revealed that the profile of the initial gas column was influenced by the gap length and delay time. Compression velocity of the initial gas column became slower as the gap length and delay time increased.