Shock-compressed carbon dioxide: Liquid measurements and comparisons with selected models

Shocked states of CO2 at pressures from 10 to 30 GPa are determined from waves driven by high explosives in systems with cryogenically liquefied carbon dioxide at T0 = 218K, ≤0 = 1.173 g/cm3, confined between parallel metal layers. Shock velocities, 4.5 ≤ U, ≤ 6.8 km/s through the liquid and particle velocities, 2.0 ≤ up ≤ 3.6 km/s, are related approximately by Us= 1.40 up,+ 1.69 (km/s). Direct comparison shows agreement within experimental precision with a recent independent result for the same initial state, and existing sparse Hugoniot data on initially solid CO, samples are reconciled indirectly through recent analytic models that represent CO2 by a spherical effective intermolecular potential. Comparisons by the empirical BKW pressure-volume-temperature equation for hot, dense molecular fluids are also developed, and the initial-state thermodynamic conditions are documented.