Laser Imaging of Secondary Breakdown Upon Nanosecond Electrical Explosion of Wire

Copper wires of diameter d = 25 mum were exploded in air by a current pulse with a rise rate of ~25 A/ns. Laser probing measurements were performed with the second harmonic of a YAG:Nd 3+ laser (lambda = 0.53 mum and Deltat = 10 ns). For the first time, laser images of the current channels were obtained upon electrical explosion of copper wires in air.