WADM and MHD modeling of wire array precursor formation for the loads of different materials and geometries

Summary form only given: The novel wire ablation dynamics model (WADM) has been recently developed and applied to simulate the implosion dynamics and to predict the implosion time of various wire array load configurations, including single- and multi-planar and nested cylindrical single material and combined material arrays. However, besides the accurate prediction of the implosion time the WADM provides the important information about the evolution of key dynamic parameters of array implosion, such as the wire mass ablation rate and the velocity of the inward streams of the ablated plasma. In its turn, these data allow the calculation of another important parameter such as the bulk temperature of the precursor plasma column. Yet, such calculation can only be considered as a rough estimation because the WADM does not resolve the spatial structure of the precursor column (thus, disregarding possible gradients of plasma temperature) and does not account for radiative cooling due to the radiation power losses. All these drawbacks, however, can be eliminated in radiation MHD modeling. This presentation focuses on the simulations of the precursor plasma column formation and its further evolution until the array implosion, using the combined WADM and MHD modeling. A substantial amount of experimental data from the diagnostic complex, including the laser probing, optical streak camera, XUV and X-ray imaging, X-ray detector signals, are used to provide the input for WADM and MHD simulations and to verify the modeling results. Study of precursor formation and evolution in the same compact cylindrical arrays but made of different wire materials shows a strong dependence of the precursor plasma parameters and radiation performance features on the material of array wires. The similarities and differences of the precursor formation and evolution in different wire array geometries, such as compact cylindrical and double planar arrays, have also been studied. The algorithm of com- ined WADM and MHD modeling has no limitation on wire array geometry, while the models of precursor dynamics provide critical information about z-pinch plasma parameters at pre-stagnation stage, which is particularly important to understand the dynamics and radiation performance of z-pinch plasma during the maximum X-ray output.