Electrical explosion of Al and Ag wires in air at different pressures

Experiments with electrically exploding fine Al and Ag wires in air demonstrate a strong dependence of the expanding metal core condition and velocity on ambient pressure. Expansion velocity of the wire core varies by 23 times between ∼0.2 km/s and ∼4.6 km/s. The shock-wave velocity at atmospheric pressure is ∼5 km/s and increases to ∼6 km/s when the pressure is decreased to 50 Torr. The condition of the metal core is strongly dependent on material and whether it is expanding into vacuum or against ambient air pressure. Expansion velocity of the fine Al and Ag wires for different surrounding pressures in general agree with Paschen's Law for air gap.