Charles A. S. Hall

Equation of state measurements in liquid deuterium to 100 GPa

Using intense magnetic pressure, a method was developed to launch flyer plates to velocities in excess of 20 km s−1. This technique was used to perform plate-impact, shock wave experiments on cryogenic liquid deuterium (LD2) to examine its high-pressure equation of state (EOS). Using an impedance matching method, Hugoniot measurements were obtained in the pressure range of 22–100 GPa. The results of these experiments disagree with the previously reported Hugoniot measurements of LD2 in the pressure range above ~40 GPa, but are in good agreement with first principles, ab initio models for hydrogen and its isotopes.

The response of ceramic powders to high-level quasi-isentropic dynamic loads.

The pulsed‐power Z machine, in an isentropic compression experiment (ICE) mode, will allow the dynamic characterization of porous materials—here various ceramic powders, e.g., Al2O3, WC, ZrO2—at roughly half their solid densities. A cylindrical configuration can provide megabar‐level loads on an annulus of the sample material. Data will be provided by velocity interferometers that measure free‐surface (or possibly interface) particle velocities. Differing sample thicknesses using stepped or conical geometries yield experimental efficiency by allowing multiple data records on single shots. With the p/α model for porous materials, the one‐dimensional Lagrangian hydrocode WONDY provides the needed analyses. Based on static data, both power‐law and quadratic crush curves are employed. Within the model constraints, we suggest that the most important parameter for characterizing the material is the crush strength, ps. With adequate sample thicknesses, the planned velocity measurements differentiate among the va...

Equation of State Measurements in Liquid Deuterium to 70 Gpa

Using intense magnetic pressure, a method was developed to launch flyer plates to velocities in excess of 20 km/s. This technique was used to perform plate-impact, shock wave experiments on cryogenic liquid deuterium (LD{sub 2}) to examine its high-pressure equation of state (EOS). Using an impedance matching method, Hugoniot measurements were obtained in the pressure range of 30-70 GPa. The results of these experiments disagree with previously reported Hugoniot measurements of LD{sub 2} in the pressure range above {approx}40 GPa, but are in good agreement with first principles, ab-initio models for hydrogen and its isotopes.