Experimental Measurements of Ion Diffusion Coefficients and Heating in a Multi-Ion-Species Plasma Shock

TL;DR

This study provides the first experimental validation of inter-ion-species transport theory in multi-ion plasma shocks, measuring ion diffusion coefficients and temperature separation to improve modeling of high-energy-density and inertial confinement fusion plasmas.

Contribution

It presents time-resolved measurements of ion densities and temperatures in multi-ion plasma shocks, validating fundamental transport theory and revealing temperature separation effects.

Findings

First experimental validation of inter-ion-species transport theory

Measurement of ion diffusion coefficients in plasma shocks

Observation of temperature separation between ion species

Abstract

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 ion diffusion coefficients. Our results provide the first experimental validation of the fundamental inter-ion-species transport theory. The temperature separation, a higher-order effect reported here, is valuable for advancements in modeling HED and ICF experiments.