A Supersonic Underwater Discharge as a High-Power Ultrasound Source

A supersonic underwater discharge system, driven by a pulsed power generator with 235 ns voltage rise time, was developed to be used as a powerful ultrasound source. The article presents details of the system's components and the various diagnostic methods used, together with the main findings obtained during the first experimental campaign. The system generated a peak pressure of 184 kPa at 1-m distance, with an efficiency of energy conversion from electrical to acoustic estimated as 0.8%. The pressure profile was found to display a resemblance to the radiation pattern generated by a dipole antenna. Using an ultrahigh-speed camera, a study of the interelectrode discharge revealed details of the prebreakdown streamer dynamics and an estimate for the lifetime of the postbreakdown plasma column. The way forward includes testing the system at a very high repetition rate.