Using FLASH to Simulate the Ablation of an Al foil into a Background Plasma*

We performed 1-D simulations of a planar shock interacting with a background plasma in the FLASH MHD code. The simulations modeled upcoming experiments that will be done on the 800 kA, 150 ns LTD pulse generator at UCSD. The current pulse is set to pass through a 5-micron thick planar aluminum foil, causing it to ablate and turn into a plasma. The J x B force and the thermal expansion of the foil accelerate it into a background hydrogen plasma at supersonic speed. In order to simulate the current drive, we placed a time-varying magnetic field on the left-hand boundary of the foil. We found that the resultant shock propagates with a Mach number of 1.43 and retains a planar configuration within the first 2 ns of the experiment. A considerable amount of species mixing was also observed at the shock front, which exhibited a 50% decrease in aluminum concentration over a span of 4 microns. This finding provides valuable insight on the behavior and dynamics of current-driven, multispecies planar shocks, an area that lacks significant research. Future work will attempt to produce results for the remainder of the experiment and will compare these with experimental results. 

Keywords: shock, plasma, multispecies, magnetohydrodynamics, Mach number