Temperature Measurements of Condensed Gaseous Hydrogen-Helium Mixtures under Multi-Shock Compression

Temperatures of multi-shock compressed gaseous hydrogen--helium mixtures with a mole component H₂:He=1:1.21 up to 7100K are measured at pressures up to 10GPa by means of an instantaneous optical pyrometer. The gas mixtures are shocked from environmental temperature at the initial pressure 20MPa. The measured second-shock temperature differs from the predictions of the non-dissociation model by up to 40% and is in good agreement with that of the dissociation model, indicating that a considerable amount of molecular dissociation occurs.