The initiation of electrical explosion of fine metal wires

Abstract

Summary form only given, as follows. The initial stage of metal wire explosion has been investigated. A pulser (3 kA, 120 kV) with fast (170 A/ns) and slow (20 A/ns) operational modes has been used. Explosions of W, Mo, Pt, Ti, Ni, Fe, Cu, Au, Al and Ag wires with diameters of 4-30 microns have been investigated. Current, voltage, laser-streaked images, and evolution of emitted visible light have been monitored during the experiment. Laser probing with 150 ps resolution has been used to get information about shape, distribution of electron density, temperature and magnetic field during explosion. Different substances, diameters, lengths, target configurations, vacuum or air environment, surface conditions, cold or hot start have been examined. Fast explosion for all substances demonstrates enhanced energy deposition and improvement of its axial homogeneity compared to the slow one. For all explosion modes energy deposition near the anode is greater than near the cathode. For refractory metals, the shape of the load plays important role on energy deposition: the X- and V-pinch configurations demonstrated enhanced energy deposition in the direction from cross point to the anode and pure energy deposition from cathode to the cross point. At slow explosion mode W and Mo wires are mainly subjected to electrical disintegration into parts. A fast exploding wire expands with the greatest velocity and emits the highest level of specific light radiation. Electronic emission from the wire surface is suggested to be playing an important part in energy deposition for refractory metals wire.