2D radiation MHD model assessment of initial argon gas distributions to be imploded on the Z machine

Summary form only given. Argon z-pinch experiments are to be performed on the refurbished Z machine at Sandia National Laboratories with a new 8 cm diameter double-annulus gas puff nozzle constructed by AASC. The gas exits the nozzle from an outer and inner annulus and a central jet. The amount of gas present in each region can be varied. Here we employ a two-dimensional radiation MHD model to theoretically investigate stability and K-shell emission properties of several measured (interferometry) initial gas distributions. Of particular interest is determining the influence that the central jet and the ratio of the amount of gas in the outer to inner annulus have on K-shell emission and stability. Our model incorporates into the Mach2 two-dimensional MHD code a self-consistent calculation for non-local thermodynamic equilibrium kinetics and ray trace based radiation transport. This level of detail is necessary in order to model opacity effects and the high temperature state of K-shell emitting z-pinch loads that can be fielded on the Z machine. Comparisons of radiation properties and stability of the AASC gas profiles are made with that of the Titan 1234 nozzle that was used in numerous successful pre-refurbished Z experiments.¹ Based on these comparisons, an optimal mass distribution for the AASC nozzle is theoretically determined and predictions are made for K-shell yields attainable from future Z experiments with this nozzle.