Using FLEXO to explore low-density plasma effects on driver target coupling and target performance in pulsed power*

FLEXO (Flux Limited EXtended Ohm's law) is an extended magneto-hydrodynamics code under development at Sandia National Laboratories. It includes extended physics such as the Hall term, electron inertia, and displacement current among others, which allows for physically consistent simulation of low-density plasma that forms in pulsed power drivers. This plasma can source from the powerfeed electrode surfaces and from the target itself. We show that this low-density plasma has a large impact on the performance of the pulsed power driver to deliver energy to the target, as well as a significant influence on the morphology of the target as it implodes and stagnates. FLEXO is being used to understand these effects and to show that the extended physics is necessary to fully capture the impact and dynamics in simulation. This presentation will focus on FLEXO simulations of fusion experiments on the 20-MA Z-machine at Sandia National Laboratories, and the important role that low-density plasma plays.