Measurements of Plasma Energy Density and Conductivity from 3 to 120 kbar

Plasma energy density, conductivity, and temperature were measured at various pressures ranging from 3 to 120 kbar. The experimental work was conducted in two parts; plasmas with pressures to 15 kbar were formed by capacitor discharges in water, and plasmas with higher pressures were formed by detonating 10 g of PETN in the water adjacent to the electrical discharge path. At 9.4 kbar and 35 000°K, the energy density was 15 J/mm3. An equation of state based upon the Debye shielding theory, without accounting for the distortion of electron quantum states, predicts an energy density of only 3.3 J/mm3. An approximate calculation is presented which accounts for these distortions, and furnishes an estimate of particle densities from measured energy densities. A peak energy density of 75 J/mm3 was obtained at 117 kbar and 1029 atoms/m3. At 10 kbar and 35 000°K, the conductivity was 3×105 (Ω m)−1 and increased with pressure. At 110 kbar and 10 000°K, the conductivity was 2.5×105 (Ω m)−1 and also was an increasing function of pressure.