For Probe Systems

If possible, try the largest tip diameter for a given power generator. 

Do not position the transducer too deep in the liquid or at the center of a symmetrically shaped flask. 

Be sure, between two successive runs, to avoid any contamination of the probe, which could affect the next result by poisoning. 

When sealing a probe into a system use the nodal (null) point for attachment. 

Provided most of these precautions are respected, the essential purpose, energy transmission from an emission zone to a reaction domain, will be successfully achieved. Users have long imagined that it was sufficient simply to switch on a generator connected to a reactor to obtain sonochemical effects. In many cases, this resulted in failure and the conclusion that sonochemistry does not work. The present development of sonochemistry requires a more rigorous approach, as demonstrated in this chapter. 

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Piezoelectric transducers are the most common devices employed for the generation of ultrasound and utilise ceramics containing piezoelectric materials such as barium titanate or lead metaniobate. The piezoceramic element commonly used in ultrasonic cleaners and for probe systems is produced in the form of a disk with a central hole. Ceramic transducers are potentially brittle and so it is normal practice to clamp them between metal blocks. This serves both to protect the delicate crystalline material and to prevent it from overheating by acting as a heat sink. Usually two elements are combined so that their overall mechanical motion is additive (Figure 10.4). Piezoelectric transducers are better than 95% electrically efficient and can operate over the whole ultrasonic range. 

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