Studies of the specific current action integral in underwater electrical explosion of butterfly shaped foils

Results of experimental research and two-dimensional hydrodynamical simulations of close to critically damped microsecond timescale underwater electrical explosions of butterfly-shaped foils for six different materials are presented. Using current and voltage waveforms along with multi-frame shadow images of the shocks generated in water, the values of the specific action integral, h, were determined. It is shown that values of h can be calculated based on the average current density and that its value (within error bars) does not change in the range of current densities (0.5–1) × 108 A/cm2. The values of h were found to be consistent with those obtained for sub-microsecond underwater electrical explosions of wires made of the same material but differ from those obtained in earlier research with explosion of wires in vacuum.