Shock Dynamics and Magneto-Rayleigh-Taylor Instability in Gas-Puff Z-Pinch Experiments

Gas-puff z-pinch experiments on Cornell University’s 1 MA COBRA generator are conducted using a custom triple-nozzle gas-puff valve. Laser shearing interferometry and time-gated XUV cameras are used to observe shock formation and evolution early during the implosion while Thomson scattering, x-ray pinhole cameras, and x-ray spectroscopy provide additional measurements at stagnation. Radial implosion velocities suggest the shocks are driven by a current layer at the outer radius of the imploding plasma which acts as piston moving inward at several hundred km/s (Potter 1978). The outer surface of this current layer is Magneto-Rayleigh-Taylor (MRT) unstable. Previous observations have demonstrated a working fluid dependence on shock structure, MRT growth rate, and x-ray yield (de Grouchy et al. 2018). Here, we build upon these observations by investigating shock evolution for various working gasses, initial density profiles, and applied axial magnetic field strengths. The effect of these parameters on the MRT growth rate and x-ray yield is discussed.