Measurement of multiple physical parameters of dense gaseous hydrogen-deuterium mixture under double-shock compression: Evaluating theoretical models from multiple views

A series of reverberating shock experiments on the precompressed hydrogen-deuterium (H-D) mixture were performed by using a two-stage light gas gun, and an elaborately designed diagnostic configuration was presented to probe the multishock states of dense fluid H-D mixtures. The particular diagnostics allowed multiple physical parameters, including the equation of state (EOS), refractive index, reflectivity, molecular polarizability, and energy gap, of H-D mixtures under double-shock compression to be simultaneously determined in a single shot. The multiple parameters obtained provide a comprehensive evaluation for existing theoretical models from multiple perspectives. It is found that, compared with the semilocal Perdew-Burke-Ernzerhof xc functional, the EOS data predicted by a nonlocal van der Waals exchange-correlation (xc) functional (vdW-DF1) are in much better agreement with the experimental results. Furthermore, the commonly used Gladstone-Dale relation is not appropriate for describing the refractive index in high-pressure-temperature regions, and the refractive index and reflectivity can be well reproduced by the Heyd-Scuseria-Ernzerhof hybrid xc functional. These observations may provide insights into future theoretical developments and a better understanding of material properties under extreme pressure-temperature conditions. Published under license by AIP Publishing.