Experimental Characterization of Diffusive Phenomena in Multi-Ion-Species Plasma Shocks Formed During Railgun-Driven Plasma Jet Collision Events

Abstract

Gradient-driven mass diffusion, or species separation, is a transport process which can occur in plasma shocks. Experimental observations of this phenomena are difficult to make, but are of interest to ongoing Inertial Confinement Fusion efforts. This body of work describes the results of two major experimental campaigns conducted at Virginia Tech's Experimental Plasma and Propulsion Laboratory to identify species separation in multi-component plasma shocks. A linear plasma-armature railgun forms and accelerates low temperature, high density, supersonic plasma jets, with the collision between two of these jets shown to induce a collisional plasma shock in the first campaign. The second campaign leverages this experimental setup while employing spatially resolved emission spectroscopy alongside collisional radiative modeling to identify species separation within multi-ion-species plasma shocks consisting of argon, aluminum, and nitrogen. These results are some of the first to be performed in a plasma shock with more than two ion species, and can be used for verification and validation of physics models of fusion plasmas. This body of work was supported by the National Science Foundation under Grant No. PHY-1903442.