Shock-Producing Mechanisms for Exploding Wires

Single-fringe interferograms are presented of 4-mil Cu wires exploded at 20 kV into argon at ambient pressures of 1/8, 1/16, and 1/32 atm. Features discernible include a compressive-head shock wave, arc plasma, a weak plasma wave and the expanding metal wire. On the basis of certain plausible assumptions it is seen that the arc plasma has a temperature of about 2.5 eV; but its leading edge, a region not in thermal equilibrium, has electron temperatures ∼ 102 eV and is the boundary of an electron-driven shock wave.