Metals during rapid heating by dense currents

Research on metals, particularly refractory metals, during pulsed heating by high density currents (up to ~ 10 7 A/cm 2 ) is reported.In particular, studies have been made of the specific heat and thermal expansion of metals in the liquid state, the resistivity in the liquid state as a function of the amount of energy supplied during free and confined expansion generating pressures up to 4-10 4 atm, the visible emission, the heat effusion, the changes in certain properties upon melting, the dispersal of a metal during an electrical explosion, and the anomalies of the specific heat and electron emission of a metal in the solid state which stem from the high rate of Joule heating.The experimental data reported on liquid metals (Al, Cu, Mo, W) at high temperatures and high pressures (tens of kilobars) are of considerable interest for the theory of liquid metals.TABLE OF CONTENTS 1. Introduction 749 2. Methodological questions 751 3. Melting and the liquid state of refractory metals 753 a) Resistance and heat of fusion, b) Resistance and thermal expansion of liquid metals; pressure dependence of the resistance.4. Electrical explosion of a metal; disappearance of metallic conductivity 757 5. Thermionic emission 761 a) Anomalies of the thermionic emission, b) Phenomena in a diode with a tungsten emitter (42).c) Thermionic-field emission.6. Specific heat 767 7. Conclusion