Publications

2D radiation MHD K-shell modeling of single wire array stainless steel experiments on the Z machine

Thornhill, J.W.; Giuliani, J.L.; Apruzese, J.P.; Chong, Y.K.; Davis, J.; Dasgupta, A.; Whitney, K.G.; Clark, R.W.; Jones, Brent M.; Coverdale, Christine A.; Ampleford, David A.; Cuneo, M.E.; Deeney, C.

Many physical effects can produce unstable plasma behavior that affect K-shell emission from arrays. Such effects include: asymmetry in the initial density profile, asymmetry in power flow, thermal conduction at the boundaries, and non-uniform wire ablation. Here we consider how asymmetry in the radiation field also contributes to the generation of multidimensional plasma behavior that affects K-shell power and yield. To model this radiation asymmetry, we have incorporated into the MACH2 r-z MHD code a self-consistent calculation of the non-LTE population kinetics based on radiation transport using multi-dimensional ray tracing. Such methodology is necessary for modeling the enhanced radiative cooling that occurs at the anode and cathode ends of the pinch during the run-in phase of the implosion. This enhanced radiative cooling is due to reduced optical depth at these locations producing an asymmetric flow of radiative energy that leads to substantial disruption of large initial diameter (>5 cm) pinches and drives ID into 2D fluid (i.e., Rayleigh-Taylor like) flows. The impact of this 2D behavior on K-shell power and yield is investigated by comparing ID and 2D model results with data obtained from a series of single wire array stainless steel experiments performed on the Z generator. © 2009 American Institute of Physics.