X-ray backlighting of the initial stage of single-wire and multi-wire Z-pinch

摘要

The initial stage of single-wire and multi-wire Z-pinch were investigated by X-ray backlighting using an X-pinch as the soft X-ray source. The experiments were carried out on the pulsed power generator PPG-I (400kA/500kV/100ns) which was designed and constructed by Tsinghua University. The source X-pinch and object single-wire or multi-wire Z-pinch are installed in the place of a current-return rod or the center between the anode and the cathode, respectively. The X-ray films with high resolution and high sensitivity were used to record the results. A resistive current probe and a Rogowski coil were used to monitor the current, and a step wedge filter was designed to measure the mass ablation rate of the thin wire. By a large number of imaging experiments, the time sequence of images for the coronal plasma formation, the inter-wire plasma merging, and the development of plasma instabilities of Z-pinch as well as some important quantitative parameters like mass ablation rate and core expansion rate were obtained.