Density evolution of a copper wire during nanosecond timescale underwater explosions

We present high-contrast X-ray images (similar to 30 mu m space and similar to 40 ns time resolution) of ns-timescale underwater electrical explosions of copper wires to the low density limit of similar to 1 g/cm(3), using a rodring electron diode as a source of X-rays. The radial density distribution, obtained by inverse Abel transform analysis of the X-ray images, is reproduced by one dimensional magneto-hydrodynamic (MHD) simulations using the SESAME equations of state and a modified Bakulin, Kuropatenko, and Luchinskii conductivity model for copper. These modifications are introduced by matching the experimental and simulated current and voltage waveforms and the radial wire expansion. For our ns-timescale copper wire underwater electrical explosions, the X-ray images display no MHD and thermal instabilities. Published by AIP Publishing.