Calculational Study of the Z-Pinch Dynamics of Resistively Thick Aluminum Rods

The fundamental limits of high-current conduction are of interest to magnetically driven ICF and other applications. Nonlinear Ohmic heating and conductor motion lead to instabilities such as the Electrothermal Instability (ETI) and Magneto-Rayleigh Taylor (MRT) that disrupt current flow. Here, the LANL, resistive MHD code, FLAG, is used to model, well-diagnosed, uncoated Al rod loads (R$_{\mathrm{0}}$ \textasciitilde 400 $\mu $m \textgreater skin-depth) in a Z-pinch configuration fielded on the Sandia Mykonos pulse generator (t$_{\mathrm{rise}}$ \textasciitilde 0.1 $\mu $s, I$_{\mathrm{peak}}$ \textasciitilde 1 MA). Results are compared to PDV measurements. Initial rod compression due to Lorentz forces in the solid-state agree well with experiments. After melt, during expansion, results with a tabular EOS that utilizes Maxwell constructs in the bi-phase region show better agreement to data than ones with Van der Waals loops. As predicted, the state of the outer layer of the rod follows the liquid/vapor coexistence curve. Finally, calculational sensitivity to EOS and conductivity are studied to better understand the expansion dynamics.