MEASUREMENTS OF THE EQUATION OF STATE OF DEUTERIUM AT THE FLUID INSULATOR-METAL TRANSITION

A high-intensity laser was used to shock-compress liquid deuterium to pressures from 22 to 340 gigapascals. In this regime deuterium is pred icted to transform from an insulating molecular fluid to an atomic met allic fluid. Shock densities and pressures, determined by radiography, revealed an increase in compressibility near 100 gigapascals indicati ve of such a transition. Velocity interferometry measurements, obtaine d by reflecting a laser probe directly off the shock front in flight, demonstrated that deuterium shocked above 55 gigapascals has an electr ical conductivity characteristic of a liquid metal and independently c onfirmed the radiography.