Comparison of microsecond and nanosecond underwater electrical discharges initiated by an electrically exploding wire

A comparison of microsecond (≤100 kA in amplitude and ≤3 μs in rise time) and nanosecond (≤60 kA in amplitude and ≤80 ns in rise time) underwater electrical discharges (WED) initiated by electrically exploding wire (Cu wire 0.1-0.5 mm in diameter and 30-85 mm in length) is presented. Parameters of the discharge channel (DC) and generated shock waves (SW) were studied by different electrical probes, optical and time resolved spectroscopy diagnostics. It was shown that the signal processing is necessary for reconstruction of correct pressure waveforms from signals obtained by the piezoelectric gauges. It was found that in the microsecond and nanosecond time scales of the UED pressure at the boundary of the DC does not exceed 4×10⁸ Pa and 20×10⁸ Pa, respectively. A model of SW generation in water by the wire initiated UED is presented. We compare the model results with the trace of the SW which is monitored by a streak camera.