ASA 124th Meeting New Orleans 1992 October

3aPA11. An electrical discharge steam bubble acoustic source.

Allen H. Olson

Stephen P. Sutton

Naval Command, Control and Ocean Surveillance Ctr., RDT&E Div., Code 711, 271 Catalina Blvd., San Diego, CA 92152-5000

Electrical energy stored in a high-voltage capacitor bank is rapidly discharged into seawater, producing a steam bubble. The expansion and subsequent collapse of the bubble compresses the surrounding fluid and radiates acoustic energy. The source process is divided into three stages: heating, expansion, and collapse. The fluid is rapidly heated by the large electrical currents passing between the electrodes. The heated fluid expands as compressed steam with a rapid increase in volume. Inertia causes the steam pressure to eventually fall below hydrostatic and the steam bubble collapses. Experimental data are presented for 1.9-cm-diam electrodes separated by 1.0 mm in 20.0-ohm cm seawater. Field strengths as high as 90 kV/cm and discharge times of between 5 and 10 (mu)s were achieved without electrical breakdown. A thermoacoustic efficiency of 1.5% was measured.