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In this paper, an experimental study was performed to document the characteristics of underwater electrical explosions involving different wires made from 15 different metals/alloys. Experiments were undertaken with those wires (4 cm in length; 100–300 μm in diameter) driven by a pulsed current source with 500 J initial stored energy. The results indicated that the electrical and thermophysical properties of the metal were critical in the explosion process. Non-refractory metals, such as Al, Cu, Ag, and Au, absorbed about twice as much energy as their enthalpy of atomization before the voltage peak, while for refractory metals, such as Nb, Mo, Ta, and W, the deposited energy before the peak was close to their atomization enthalpy. Accordingly, the strongest measured shock wave for non-refractory metals was 12.4 MPa (peak pressure) while that for refractory metals was only 8.5 MPa (peak pressure). By contrast, the light intensities of non-refractory metals were at least an order of magnitude lower than those of refractory metals. From 100 to 300 μm, the estimated average temperature at the plasma-water interface decreased from ∼10 000 K to ∼4000 K. It was also found that, as evidenced from the time-integrated spectra, obvious chemical reactions occurred between water and relatively active metals such as Al, Ti, and Fe. In addition, Pt and Au, which have high first ionization energies, exhibited longer current pauses (>50 μs) or vaporization phases relative to the other metals.

This paper presents the characteristics of underwater electrical wire explosion (UEWE) with three discharge types, namely, Type-A, Type-B, and Type-C. Experiments were carried out with copper and tungsten wires (4 cm long and 50–300 μm in diameter) driven by a microsecond time-scale pulsed current source with 500 J stored energy. A time-integrated spectrometer and a photodiode were used to measure the optical emission of UEWE. A Polyvinylidene Fluoride probe was adopted to record the pressure waveforms. Experimental results indicate that from Type-A to Type-C, more energy deposits prior to the voltage peak and the first peak power increases drastically. This variation of energy deposition influences the optical emission and shock wave generation process. Specifically, the light intensity decreases by more than 90% and the peak of continuous spectra moves from ∼400 nm to ∼700 nm. In addition, the peak pressure of the first shock wave increases from ∼2 MPa to more than 7.5 MPa.