Multiphase Foamlike Structure of Exploding Wire Cores

X-ray backlighter images (radiographs) of current-induced explosions of 7.5-25 {mu}m diam metal wires show for the first time {mu}m scale, time-resolved details of a persistent foamlike liquid-vapor structure of the expanded wire core. Experiments with refractory and highly resistive metals, with current rising to 2-5 kA per wire in 350 ns, show that a substantial portion of the wire material is not vaporized but remains in a condensed state. As the current damps out, the remaining liquid phase material coalesces into separate droplets. (c) 1999 The American Physical Society.