Correlated X-Ray and Optical Streak Photographs of Exploding Wires

Abstract

Sequences of flash x-ray photographs of 70 nsec-duration obtained during the early expansion of copper, lead, and iron wires are correlated precisely in time with the electrical voltage pulse and optical streak photographs. Wire sizes were 10, 15, and 25 mil in diameter. The x-ray pictures show the onset and development of striations in each of these metals along the wire length during the fast resistance rise of the wire. The relatively smooth envelope of the radially expanding striations is compared with features of the optical streak pictures. Some of these optical pictures show a translucent radial cloud developing prior to the fast resistance rise, and a more opaque inner core which expands radially. Most of the striations in the x-ray pictures appear to be completely separated at the voltage maximum. After the voltage peak, the density of material appears to be greater further from the center. The observed behavior is discussed.