Collisional plasma shocks generated from supersonic flows are an important
feature in many astrophysical and laboratory high-energy-density plasmas.
Compared to single-ion-species plasma shocks, plasma shock fronts with multiple
ion species contain additional structure, including interspecies ion separation
driven by gradients in species concentration, temperature, pressure, and
electric potential. We present time-resolved density and temperature
measurements of two ion species in collisional plasma shocks produced by
head-on merging of supersonic plasma jets, allowing determination of the
diffusion velocity of the ion species. Our results demonstrate that the lighter
ion species diffuse faster than the heavier species within a shock front,
consistent with predictions from the inter-ion-species transport theory.
Results from the experiment approach quantitative agreement with theoretical
prediction and 1D ion-Fokker-Planck kinetic simulation