The effect of insulating coatings on exploding wire plasma formation

Substantial increases are reported in the expansion rates of exploding, dense wire cores under conditions simulating the prepulse phase of wire array z-pinch experiments [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)] using wires with insulating coatings. The insulation apparently allows additional wire heating by delaying the formation of plasma around the wires. Once plasma is formed it terminates significant current flow in the residual wire cores. This effect is demonstrated for 25-μm diameter W and 25-μm diameter Ag wires.