Plasma Formation and Ablation Dynamics in Thin-Foil Cylindrical Liner Experiments

Abstract

In this chapter, the formation of plasma and subsequent ablation dynamics of metallic liner z-pinches is investigated, in the case where the liner wall is thin with respect to the skin depth of the applied current pulse. The ablation dynamics of wire array z-pinches have been extensively studied in order to understand and improve the mechanisms for generating x-rays, both for ICF research and for other HEDP applications. The ablation dynamics of liners have not yet been studied in any detail. The dynamics will differ to those of a wire array because both the magnetic field configuration and the initial azimuthal distribution of mass are different. The cylindrical liner has a global magnetic field around the azimuth, whereas a wire array has a global component, and local components around individual wires. Additionally, in a liner, there are no gaps through which global magnetic field can push material ablated at the outside surface radially inwards. Z-pinch based ICF schemes have recently geared away from using wire array implosions as indirect drive x-ray sources, and have moved towards direct compression of fuel with imploding solid wall liners (see Chap. 1). Additionally, z-pinch x-ray sources running on more powerful machines in the future may be able to dispense with using discrete fine wires and again turn to liners. With these things in mind, it is of use to the greater z-pinch community to study liner ablation. In the context of this thesis, liner ablation is also investigated as a possible mechanism for driving shock physics experiments.