External Magnetic Field Effects on Ablation of Current-Driven Foils Using an Extended Magnetohydrodynamics Simulation

We numerically model the ablation process of a 25-μm-thick aluminum foil driven by a pulsed-power machine that provides a 1-MA peak current in a 100-ns zero-to-peak rise time. The extended magnetohydrodynamics simulation is a discontinuous Galerkin code with Cartesian coordinates in 3-D and with 25-μm spatial resolution. We investigate the influence of an external magnetic field normal to the foil surface, B
_z
. During the foil ablation, B
_z
= 1 T causes more nonuniform distributions of density and current compared to B
_z
= 0 T. B
_z
= 4 T delays the generation of surface plasma relative to the 0- and 1-T cases. The understanding of a material's ablation as it undergoes transition from the solid to plasma phases requires detailed knowledge of a material's equation of state and conductivity. This paper of warm dense matter and how instabilities propagate from a solid material to plasma motivates improvements to both numerical simulations and experimental diagnostics.