Ultrasound generation produces in general an acoustic field, characterized by both inertial and non-inertial acoustic cavitation, a process by which non-linear oscillation of a microbubble and its associated micro streaming and radiation force generated by ultrasound can lead to intense heating effects in a material, solution or biological cell which comes into contact with a conventional ultrasound transmission. Typically an ultrasound signal contains both an acoustic vibration effect, a resonance effect where a material receiving the ultrasound transmission resonates in response to the transmission, and unfortunately in many applications a damaging cavitation effect and a damaging thermal effect. This invention is both a method and an apparatus to reduce the damaging effects of ultrasound in both the thermal and mechanical effects and to provide a safer ultrasonic process which can be used in sonochemistry applications, material science and for biological or medical applications.
