Electrical conductivity of copper in the low temperature region of warm dense matter

Abstract

In this study, electrical conductivity of copper in the low temperature part of a warm dense matter regime is investigated utilizing underwater electrical wire explosion. Specifically, for the vapor/plasma region with a density of ∼0.01 normal density, temperature up to 10 kK, and the liquid–vapor two-phase region below the binodal curve, the electrical conductivity of copper is measured as a function of density and temperature by means of shadowgraph imaging, spectroscopy, and electrical measurements. In this region, anomalous temperature dependence and characteristics originated from a phase transition are found. Based on the careful analysis of experiments and model calculations, it is revealed that bound electrons, in addition to free electrons, contribute significantly to the electrical conductivity in the vapor/plasma region, and that the associated phase transition kinetics play a substantial role in adequately describing the behavior in the liquid–vapor two-phase region. An improved electrical conductivity model emerging from our combined experimental and theoretical study that accounts for the characteristics in the low temperature regime of the warm dense matter is presented.