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

Abstract

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 ≤ u_p ≤ 3.6 km/s, are related approximately by U_s= 1.40 u_p,+ 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.

Key Words:

• Carbon dioxide
• cryogenic liquid
• dense fluid
• equation of state
• Hugoniot
• shock waves.