Measurement of the Electrical Conductivity of Metals in the Vicinity of the Critical Point

Measurement of the electrical conductivity of metal plasmas at near-solid densities is made possible by rapid vaporization of metal wires in water. The water acts as a tamper, slowing the expansion of the plasma and ensuring a welldefined cylindrical boundary. Measurement of the time-varying resistance is straightforward, and the conductivity and density are easily deduced after the column diameter is measured photographically. Temperature may be deduced from the measured energy input with help of an equation of state provided by the LANL SESAME tables. Measurements have been made on copper, aluminum, and tungsten plasmas. The electrical conductivity is almost independent of temperature at the highest densities. Conductivity falls steeply with falling density and reaches a minimum at a few percent of solid density, rising with further reduction in density. Near the minimum, the temperature dependence of the conductivity becomes appreciable.