Atomization and merging of two Al and W wires driven by a 1 kA, 10 ns current pulse

Possibility of preconditioning of wires in wire array Z-pinch loads by an auxiliary low-level current pulse was investigated in experiments with two aluminum or two polyimide-coated tungsten wires. It was found that the application of a 1 kA, 10 ns current pulse could convert all the length of the Al wires (1 cm long, 15 mu m diameter) and similar to 70% of length of the W wires (1 cm long, 15 mu m diameter, 2 lm polyimide coating) into a gaseous state via ohmic heating. The expansion and merging of the wires, positioned at separations of 1-3 mm, were investigated with twowavelength (532 nm and 1064 nm) laser interferometry. The gasified wire expanded freely in a vacuum and its density distribution at different times could be well described using an analytic model for the expansion of the gas into vacuum. Under an energy deposition around its atomization enthalpy of the wire material, the aluminum vapor column had an expansion velocity of 5-7 km/s, larger than the value of similar to 4 km/s from tungsten wires. The dynamic atomic polarizabilities of tungsten for 532 nm and 1064 nm were also estimated. Published by AIP Publishing.