End-on laser probing of the ablation phase of wire array z-pinch implosions on the magpie generator

Summary form only given. New end-on measurements have taken of the areal electron density distribution of wire array z-pinches during the ablation phase. These measurements have been used to investigate the differences in dynamics between aluminium and tungsten arrays. The experiments were carried out on the 1.4 MA peak current, 240ns rise-time MAGPIE generator at Imperial College, London. The measurements were taken using a two colour Mach-Zender style imaging interferometer. Probing is provided by the 2^nd and 3^rd harmonics (532nm and 355nm) of a pulsed Nd:YAG laser with a pulse duration of ~500ps. In addition, a time resolved Quadrature Interferometer, powered by a CW diode pumped Nd:YAG laser has been used to calibrate these measurements. The fringe shift due to a specific line through array is tracked in time. By comparing the fringe shift at the moment an image is taken with the shift at corresponding point in the image, the fringe shift and thus the electron density can be calibrated unambiguously over the entire array cross-section. Results are presented and comparisons made to both the rocket model and simulations produced using the GORGON MHD code.