Measurement on the Electrical Conductivity of the Dense Copper Plasma Along the Binodal Curve

Knowledge on the thermophysical properties are crucial for theoretical and experimental studies of warm dense matter (WDM). In this work, we present the electrical conductivity data of copper along the binodal curve in the WDM regime as a function of mass density and temperature. All data are obtained using the underwater wire explosion technique, in which vaporized copper cools along the gas branch of the binodal curve during the current dwell period after the wire explodes. Mass density and temperature are measured by fast imaging and optical spectroscopy, respectively. In contrast to a previous technique, the spectrum emitted by copper plasma is collected at one end of the plasma to exclude spectral distortions incurred by water plasma. We find that this method provides a reliable blackbody spectrum compared with the emission spectra collected across the water plasma layer. The measured temperature data show good agreement with the theoretical binodal curve for copper. Combining these data with the wire resistance measurement, we obtain the conductivities of copper along the binodal. We expect that our methodology suggested here can also be utilized to other materials for various temperatures and densities by changing wire materials and operating conditions of the wire explosion.