| The purpose of this experiment was to examine the exploding wire phenomena in various diameter fibers and correlate the results with previous work performed oil wires of much larger diameter. With the onset of the age of microtechnology and miniaturization of circuits, the expansion of knowledge in this area into the nearly microscopic realm is vital. In 1965, German scientists R. Winkler, W. Bertoldi, and H. Kressner proposed a classification scheme based on the physical processes which occur following the explosion of a wire. Their scheme consists of four classes of explosion: (1) melting, (2) explosion with current cutoff, (3) explosion with dark interval, and (4) explosion without dark interval. Winkler's work with copper wires also suggested smaller diameter samples would require less energy for the initiation of the exploding wire phenomena. In this work Winkler's classification scheme is applied to commercially available fibers (pitch graphite, pan graphite, and stainless steel). The concept of smaller energy requirements for explosion at smaller diameters was examined. Winkler's wires were 0.07 and 0.14 mm in diameter. Fiber diameters used in this work were 3.7 and 8.0 micron pan graphite, 10.0 micron pitch graphite. 4.0, 8.0, and 12.0 rnicron uncoated stainless steel. and 8.0 and 12.0 micron coated stainless steel. Coatings on the stainless steel fibers were polyvinylchlorlde (PVA). Diameter measurements were made using scanning electron microscopy, and conductivity measurements were made using a four-point probe. These measurements were used in calculations to determine if the skin effect was a contributing factor to the exploding wire phenomena for the samples studied. Fibers were mounted across high-voltage electrodes. Current vs. time waveforms were obtained when the fibers were destroyed by high-energy current pulses. These waveforms were compared to those in Winkler's classification scherne. Based oil Winkler's scheme, most waveforms were consistent with the explosion without dark interval classification. Stored energy) in the capacitor used to explode the fibers was 0.566 Joules (Wsec) as compared to the minimum of 5 to 50 Joules (Wsec) Winkler required to achieve explosion without dark interval for his wires. |
