Experimental investigation of arc formation and bubble expansion initiated by pulse discharge in water

Dynamic pressure wave generated by underwater pulse discharge are widely used in many industry applications including rock fragmentation, oil stimulation and acoustic source. A test stand was developed to measure the amplitude and waveform of dynamic pressure wave produced by underwater pulse discharge. Besides, the pulsations of underwater arc and the gaseous bubble generated by pulse discharges in several tens of microseconds were observed by a high speed camera with a frame speed at 525 kfps. Two distinct phases characterizing different arc shapes are observed and distinguished. The energy of shock wave and that of arc are calculated and compared in detail. Based on results of observation and energy analysis, it can be concluded that the water-atmosphere arc phase (more precisely, 0-15 μs after breakdown in this paper) exacts a decisive impact on the generation of shockwave. Which probably leads to necessary reconsiderations of several fundamental assumptions in modeling of.