Abstract
When an ultrasonic cavitation is produced, many different frequency components of sound pressure
in water are generated. The sound pressure of fundamental frequency, subharmonics, and harmonics were
compared with the cavitation threshold obtained from white noise. When the electric power which applied to
the transducer was gradually raised, the harmonic component appeared first, the sound pressure of
fundamental frequency became unstable near the cavitation threshold, after the cavitation was produced,
subsequently followed by the generation of the subharmonic component. After average of sound pressure (AP)
and average of broadband sound pressure (ABP) were defined, it was possible to compare the white noise with
the subharmonic and harmonic components. The cavitation threshold values were measured in the frequency
range from 22 kHz to 5 MHz. The threshold values of the erosion of aluminum foil, and I3
-generation of the KI
method were measured. The threshold values of I3
-generation were almost the same as the cavitation threshold
values at all frequency. Although the threshold values of erosion less than 100 kHz were close to the cavitation
threshold values, above 100 kHz, the threshold values of erosion became larger than that of the cavitation.
