Investigation of 1-MA, 200-ns Ar Gas Puff Z-Pinches on COBRA

We have conducted Ar gas puff z-pinch studies on the COBRA generator. A triple-nozzle is used to produce tailored gas density distributions with two concentric annular nozzles and a center gas jet. We report suppression of Rayleigh-Taylor instabilities by inner dense plasmas, and photo-ionization of the inner gas puffs by the hot outer imploding plasma. By varying the initial gas density profiles, we have optimized the Ar K-shell x-ray radiation, and produced stable 200-ns implosions.