Development of high power ultrasound for acoustic source applications

The detection and identification of undersea objects is achieved using acoustic pulses which travel long distances through water. The quality of the information obtained from a pulse improves with increasing signal strength and bandwidth. However the combination of high power and bandwidth is difficult to achieve from conventional, electromechanical acoustic sources. The desired characteristics can be achieved by the generation of high power ultrasound (HPU) using pulsed power technology. High-voltage pulses used to form a plasma channel during the breakdown of water produce acoustic shock waves of high power and frequency content. Work at the University of Strathclyde is currently underway to improve the understanding of the mechanism of HPU generation using pulsed power and thus allow the optimisation of the conversion of electrical energy into acoustic energy. The results of initial experiments to systematically generate and characterise high power acoustic pulses are presented. Analysis of the detected pulses, including wavelet time-frequency analysis is discussed.