Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

We report spatially resolved measurements of the oblique merging of two supersonic laboratory plasma jets. The jets are formed and launched by pulsed-power-driven railguns using injected argon, and have electron density $\sim 10^{14}$ cm$^{-3}$, electron temperature $\approx 1.4$ eV, ionization fraction near unity, and velocity $\approx 40$ km/s just prior to merging. The jet merging produces a few-cm-thick stagnation layer, as observed in both fast-framing camera images and multi-chord interferometer data, consistent with collisional shock formation [E. C. Merritt et al., Phys. Rev. Lett. {\bf 111}, 085003 (2013)].