Structure on the dense residual wire core during exploding wire plasma formation

Summary form only given. High resolution (1-5 micron, 0.7-2 ns) X-ray (2-4 keV) backlighting has been used to study the formation of plasma when single wire and multiwire arrays are exploded using the /spl sim/450 kA XP pulser at Cornell University. The wire plasmas were imaged using 13-25 micron Mo wire, and 20 micron Pd wire, 150-200 kA X-pinch X-ray backlighters which were <5 microns in size and about 1 ns in duration. It is well established now that an exploding wire plasma produced by a /spl sim/100 ns pulsed power generator initially consists of a relatively low density coronal plasma surrounded by a dense residual wire core. Two images of the wire cores separated in time by 5-20 ns have been obtained 40-70 ns after the start of the current pulse with 2-4 keV X-rays using different geometries. Fine structure on the wire core surface with a spatial scale of 10-20 microns has been recorded on film at times when the wire core is about ten times that diameter. The structure, which appears to be dominantly azimuthally symmetric, is reminiscent of the Rayleigh-Taylor instability, and it is observed to increase in amplitude from the first backlighter frame to the second.