Electrical conductivity of tungsten in a continuous transition from condensed to gaseous state

A pulse heating technique is developed that makes it possible to investigate the transition of a metal from a condensed to a gaseous state while maintaining almost uniform temperature and pressure distributions in a sample. By means of the technique, the electrical conductivity of tungsten was measured in a process during which a pressure in the range of 30-100 kbar was applied to the sample and its density decreased from the standard solid density to a density 15-20 times less. Since the pressures are substantially higher than the critical pressure, the transition from a condensed to a gaseous state was continuous. Earlier results have shown that along isobars in the range of 30-60 kbar the density dependence of the electrical conductivity changes radically at a certain density value (at which it has a pronounced knee). At the knee, the density is approximately 10 times less than the standard solid density, and the internal energy is about two times the sublimation energy. The dependence of the electrical conductivity near the knee becomes smoother as the pressure increases. In this paper new results on the conductivity of tungsten at the pressures up to 100 kbar are presented. It is shown that the knee becomes remarkably flatter and smoother than the corresponding low pressure dependence. Nevertheless, the main features of the electrical conductivity dependence observed at low pressures persist at the maximum applied pressure.