Extended MHD in the Ares multiphysics code*

The Ares multiphysics code models a variety of processes relevant to high-energy-density systems, including radiation hydrodynamics, laser energy deposition, thermal conduction, atomic physics, themonuclear burn, and magnetohydrodynamics (MHD). Pulsed power experiments provide a demanding setting for multiphysics codes, requiring accurate models for solid-density, room-temperature materials and low-density, high-temperature plasmas. To improve the fidelity of the low-density plasma treatment, Hall MHD has been implemented in the 2D MHD package in Ares. The algorithm and implementation have been benchmarked using a Hall drift wave problem [J. D. Huba, Space Plasma Simulation, Springer (2003)]. The Hall term introduces short-timescale oscillations that can drastically limit the numerical timestep when modeling pulsed power experiments. To mitigate these impacts, a combination of algorithmic modifications and subcycling have been implemented. This presentation will focus on these and other improvements to the treatment of low-density plasmas in the context of pulsed power systems.
LLNL-ABS-753700