Characterization of Collisional Shock Structures Induced by the Stagnation of Railgun-driven Multi-ion-species Plasma-jets

The study of shock-waves in supersonic plasma jets is essential to understanding the complex dynamics involved in many physical systems. Specifically, ion-species separation caused by a shock wave propagating through a plasma is an important but not yet well understood phenomenon. In inertial confinement fusion implosions, a shock wave precedes the rapid compression of a fuel pellet to ignition conditions that theory and computational studies suggest may be separating the fuel and reducing the neutron yield. In astrophysics, the shock wave produced when a supernovae explodes has been shown to have an effect on nucleosynthesis as a result of shock heating. In both these cases the time and length scales make them difficult to study experimentally, but experiments on more reasonable scales can shed light on these phenomena. This body of work provides the basis for doing just that. The work begins by describing the development of a small, linear, plasma-armature railgun designed to accelerate plasma jets in vacuum to high-Mach-number. This is followed by discussion of an experimental campaign to establish a plasma parameter space for the jets, in order to predict how effectively the accelerator can be used to study centimeter-scale shock structures in jet collisions. The final section presents an experimental campaign in which jet collisions are induced, and the resultant structures that appear during the collision are diagnosed to assess how conducive the experiment is to the future study of shock-wave induced species separation in laboratory plasmas. This work is a foundation for future experimental studies of ion-separation mechanisms in a multi-ion-species plasma. This research was supported in part by the National Science Foundation under grant number PHY-1903442.