High power ultrasound for acoustic source applications

High power ultrasound (HPU) can be generated by the application of pulsed power technology to produce acoustic waves of high power and bandwidth. A study was conducted into the variation of the amplitude and frequency content of the acoustic signal with the applied voltage, pulse energy and electrode separation. Measurements indicate that, for a given electrode separation, whilst there is some increase in the amplitude of the detected acoustic emission with an increase in the electrical pulse energy it is only a modest effect. For a given pulse energy a considerably greater increase in the acoustic signal is observed when the distance between the electrodes is extended-thereby increasing the size of the signal source. The maximum amplitude of the detected signal approximately varies as the electrode separation to the power of 2/3. At large separations the delay time between the application of the voltage pulse and the breakdown of the water is considerable thus allowing energy loss through ionic conduction in the water.