An apparatus and method for characterizing cavitation that occurs in a
fluid exposed to acoustic energy. The apparatus comprises a vessel for
holding the fluid; an acoustic energy generating means for generating
acoustic energy, the acoustic energy generating means being positioned to
transmit the acoustic energy into the fluid while the fluid is held in
the vessel; and a cavitation detection means for detecting cavitation in
the fluid held in the vessel. In a preferred embodiment, the cavitation
detection means comprises a light detection means, such as a
photomultiplier tube, that detects sonoluminescent emission from the
fluid. The method comprises the steps of exposing a volume of process
fluid to acoustic energy at a specified power level; measuring the photon
output from the fluid over a period of time; and when the photon output
deviates from a desired level, initiating a remedial step to bring the
photon output back to approximately the desired level.