Development of a variable frequency heterodyne sonication system

Almost all available instruments used in sonochemistry produce ultrasound at a fixed frequency. There is no commercially available instrument which produces ultrasound at a wide range of frequencies. The main problems in making such an instrument is that ceramic's characteristics change widely with frequency, and it is consequently difficult to develop a drive circuitry which drives the instrument over a wide range of frequencies. The instrument designed in this thesis is unique because it produces ultrasound over the frequency range from 150 kHz to 500 kHz for use in sonochemical studies. The lossless matching circuit designed here successfully matches the complicated variations of the impedance of the ceramic over the above frequency range, thus making the instrument very versatile . The instrument has two transducers, so that frequency as well as heterodyne effects can be examined. In the Variable Frequency Heterodyne Sonication System, two waves of different frequencies are produced and sent into the glass cell. Heterodyne components are expected to produce more sonochemical reaction sites and hence ultimately to lead to increased cavitation collapse efficiency. Calorimetric and chemistry experiments were performed. Frequency and heterodyne effects were examined.