3D modeling of instabilities in multi-wire Z pinches

Summary form only given. Recent success in generating large X-ray energies and powers from large wire-number Z pinch arrays has revived a strong interest in MHD and magneto-Rayleigh-Taylor (RT) instabilities. Two-dimensional r-z simulations of Z pinches typically start calculations with a preformed plasma sheath and seed RT instabilities with a random density perturbation. The magnitude of the random density perturbation is tuned so that the calculated X-ray radiation pulse matches the amplitude and pulse-width of experimentally measured data. While these calculations have been extremely useful in understanding the effect of RT instabilities on experiments, they do not capture all of the three-dimension structure seen in experimental images and are not truly predictive in nature. To remedy this shortcoming Sandia is developing a 3D finite element, ALE, radiation MHD code called ALEGRA. In this paper we present an overview our efforts to use ALEGRA to simulate one class of problems important to the 3D into a plasma sheath.