Ablation and Precursor Formation in Copper Wire-Array and Liner $Z$-Pinches

Abstract

Density maps of the r-θ plane are presented for two basic types of loads with the same total mass and overall dimensions: wire arrays and cylindrical liners. The wire-array load shows complex interactions of the ablation streams, leading to a well-developed precursor plasma on the axis. Some of the liner loads were near-perfect cylinders, whereas other liners had small perturbations to the cylindrical shape. The near-perfect liners had azimuthally uniform and reduced ablation on the inner surface compared to the wire array. This leads to a plasma prefill that was approximately an order of magnitude less dense than that produced by equivalent wire arrays. The perturbed liners had enhanced ablation near the perturbations that destroyed the azimuthal symmetry of the plasma prefill. The plots of azimuthally averaged mass density and ablated-mass-to-load-mass ratio versus radius are presented, as well as comparisons to the rocket model.