Neon and argon multi-nozzle gas puff z-pinch studies on COBRA

Summary form only given. In the past, we have produced stable z-pinch implosions with an outer Ne shell imploding on an inner Ar (Ne-on-Ar) gas puff load. Using a similar mass density profile to the Ne-on-Ar experiments, we observed that Ar-on-Ne implosions were not stable. In this paper, we present the investigations of the Ne-on-Ar and Ar-on-Ne implosion dynamics with various mass density profiles. The experiments are conducted on the 1-MA, 200-ns COBRA generator. A triple-nozzle is used to produce z-pinch loads with concentric outer and inner annular gas puffs and a center gas puff. Z-pinch loads such as Ne-on-Ar and Ar-on-Ne with or without a center gas jet will be tested. In the experiments, we will use Planar Laser Induced Fluorescence (PLIF) to determine the initial gas puff mass density profile, and a three-frame Laser Shearing Interferometer (LSI) for imploding plasma density profiles. Two four-frame gated XUV cameras capture the implosion plasma structure. A multi-channel, filtered pinhole x-ray camera images the pinch plasma. The Ar and Ne x-ray spectra will be recorded by a spherical crystal x-ray spectrometer. Two spatially resolved UV and visible light spectrometers are used to measure the emission line profiles. The measurements will be compared with the predictions from a 2D multi-material radiation MHD model.