Gas puff Z-pinch implosions on COBRA

Abstract

Summary form only given. In this paper, we present investigations of 6-cm diameter Neon gas puff Z-pinch implosions. The experiments are conducted on the 1.2-MA, 200-ns COBRA generator. Several z-pinch load configurations are tested, such as neon gas puff with or without external magnetic field, and neon gas puff with a metal wire on the pinch axis (puff-on-wire). A Planar Laser Induced Fluorescence (PLIF) system, a Laser Shearing Interferometer (LSI), a Laser Wavefront Analyzer (LWA), gated UV and pinhole x-ray cameras, an x-ray spectrometer and a fiber optic Faraday rotation Bz field sensor are used as the diagnostics. The PLIF measurements, which give the initial gas density profiles, are conducted on a test-bed under similar conditions to those in the z-pinch experiments. In the LSI and LWA measurements, a 4-ns, 25-mJ, 532-nm Nd:YAG laser was used. The implosion velocity, mean ion charge states and then the imploding plasma temperatures are obtained at various implosion times. The imploding plasma sheath structure and Rayleigh-Taylor (RT) instability are monitored. We have demonstrated that the fiber optic Faraday Rotation Sensor is capable of measuring the implosion currents in the load region and the magnetic fields trapped in z-pinches. More details will be presented in the report.