Measurement of convergence ultrasound in cone-like bubble structure using light deflection method

High intensity ultrasound irradiated from a horn surface in water forms a cone-like bubble structure (CBS). The ultrasound field in the CBS is highly nonlinear and converged at a certain point distant from the horn surface on the horn axis. The mechanism of the CBS was investigated and partly confirmed by the computer simulation. However, the experimental data of the acoustic cavitation field and the pressure field in the CBS are not enough. In this report, the measurement method of the low frequency ultrasound field formed in the bubbly water using the laser deflection and the acoustic cavitation bubble distribution using the laser scattering were proposed. The proposed method was applied to the measurement of the CBS under the horn with 30 mm diameter irradiating 19.2 kHz ultrasound at input power to the transducer is 90 W. The cross-sectional ultrasound and acoustic cavitation fields were obtained and the qualitative agreement of behavior of measured and previously reported fields were confirmed.