Design and optimization of a liner-on-target injector for staged Z-pinch experiments using computational fluid dynamics and MHD simulations

Abstract

Summary form only given. Previous Staged Z-pinch experiments have demonstrated that gas liners (or puffs) can efficiently couple energy to a target plasma and implode uniformly, producing plasmas in High Energy Density (HED) regimes. In these experiments, a 50 kJ, 1.5 MA, 1 μs current driver was used to implode a magnetized, Kr liner onto a D+ target, producing 1010 neutrons per shot. Time-of-flight data suggested that primary and secondary neutrons were produced. MHD simulations show that, using optimized liner and plasma target conditions, neutron yield could be further increased in Staged Z-pinch implosions using the Zebra machine, a 1.5 MA and 100 ns rise time current driver. In this work we present the design and optimization of an injector for these experiments. The injector is composed of an annular high atomic number (e.g. Ar, Kr) gas-puff and an on-axis plasma gun that delivers the ionized deuterium target. The gas-puff nozzle optimization was performed using the computational fluid dynamics (CFD) code Fluent and the MHD code MACH2. The CFD simulations produce density profiles as a function of the nozzle shape and gas. These profiles are initialized in MACH2 to find the optimal liner density profile for a stable, uniform implosion that produces high neutron yield.