Triple nozzle gas-puff z-pinch implosions on COBRA

Abstract

Summary form only given. We present investigations using a triple-nozzle, 6cm outer diameter gas puff for fast z-pinch implosions. Experiments are conducted on the 1MA, 200ns COBRA generator at Cornell University. Centimeter thickness cylindrical shells of neon/argon gas at typical densities of n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> are imploded onto a 4cm outer diameter inner gas shell and both subsequently converge at the pinch axis. The configuration is examined with and without a central gas jet and the influence on instability growth rates is investigated. The structure of the imploding plasma sheath and Rayleigh-Taylor (RT) instabilities are imaged and quantified under different mass loading and radiative efficacy in each of the three puffs.The diagnostic suite used to characterize implosion dynamics enables measurement of density distributions before and after the arrival of current in the gas shells. Neutral gas density distributions are characterized prior to each experiment using a Planar Laser Induced Fluorescence (PLIF) system. Plasma density profiles are captured during each implosion by a three-frame Laser Shearing Interferometer (LSI) and a twoframe Laser Wavefront Analyzer (LWA). Plasma dynamics are recorded using two 4-frame, 2ns gated EUV pinhole cameras and thermodynamic properties by a multi-spherical crystal x-ray spectrometer capturing spatially resolved spectra. These measurements enable us to obtain implosion veSummary form only given. We present investigations using a triple-nozzle, 6cm outer diameter gas puff for fast z-pinch implosions. Experiments are conducted on the 1MA, 200ns COBRA generator at Cornell University. Centimeter thickness cylindrical shells of neon/argon gas at typical densities of n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> are imploded onto a 4cm outer diameter inner gas shell and both subsequently converge at the pinch axis. The configuration is examined with and without a central gas jet and the influence on instability growth rates is investigated. The structure of the imploding plasma sheath and Rayleigh-Taylor (RT) instabilities are imaged and quantified under different mass loading and radiative efficacy in each of the three puffs.The diagnostic suite used to characterize implosion dynamics enables measurement of density distributions before and after the arrival of current in the gas shells. Neutral gas density distributions are characterized prior to each experiment using a Planar Laser Induced Fluorescence (PLIF) system. Plasma density profiles are captured during each implosion by a three-frame Laser Shearing Interferometer (LSI) and a twoframe Laser Wavefront Analyzer (LWA). Plasma dynamics are recorded using two 4-frame, 2ns gated EUV pinhole cameras and thermodynamic properties by a multi-spherical crystal x-ray spectrometer capturing spatially resolved spectra. These measurements enable us to obtain implosion velocity, mean ion charge states and plasma temperature at various positions and implosion times.locity, mean ion charge states and plasma temperature at various positions and implosion times.