Ultrahigh energy efficiency from a supersonic underwater ultrasound source

What is it about?

The present work is dedicated to an experimental and theoretical study of an innovative, powerful and extremely energy efficient underwater ultrasound source. The source works using a technique in which a pulsed power generator using the impedance mismatch of a long high-voltage coaxial cable generates a train of voltage impulses with a very high pulse repetition frequency of the order of a few MHz. Applying this train of voltage impulses to a pair of underwater electrodes generates a streamer-initiated breakdown of water and, subsequently, a plasma column connecting the electrodes over a very large inter-electrode gap of 55 mm. The interaction of the long plasma column thus formed with the surrounding water produces a rapidly expanding vapor bubble, an ‘instrument’ producing a strong pressure wave with an overall energy efficiency of 24%, an order of magnitude higher than most underwater pressure sources reported in the literature. The new system will certainly be of interest for a number of important industrial applications.

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Photo by Noah on Unsplash

Photo by Noah on Unsplash

Why is it important?

The most important characteristic of the new pressure source is that it requires an extremely low energy. For example, with only 125 J stored in a high voltage capacitor, a peak pressure in the range of 3 MPa has been generated at 0.5 m distance from the source.

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