Characterization of Multi-Ion-Species Shock Structures in Railgun-Driven Plasma Jet Experiments*

Shocks are induced and characterized by colliding high-Mach-number plasma jets with stagnated plasma. A linear railgun serves as the plasma source, where injected argon gas mixes with impurities ablated from the internal components of the gun to form multi-ion-species plasma jets. These jets exist in a collisional regime, with density $\approx10^{16}~\mathrm{cm^{-3}}$ and temperature $\approx2~\mathrm{eV}$. The collision event produces a stagnation layer which is characterized using multi-chord interferometry, fast photography, and spatially-resolved spectroscopy. Plasma parameters measured and inferred from these diagnostics suggest that this stagnation layer is consistent with the formation of a collisional shock. Present efforts focus on spatially resolving the distribution of ion species in the pre- and post-shock plasma. The resulting data will have the potential to validate physics models relevant to astrophysical and high-energy-density plasmas.