高強度集束超音波の気泡界面での後方散乱によるキャビテーション気泡クラウド形成の実験的検討

抄録

The cavitation bubble cloud formation due to the backscattering of high-intensity focused ultrasound (HIFU) from a laser-induced bubble and the bubble collapse near a gelatin-water interface have been investigated experimentally. High-speed video camera and fiber optic prove hydrophone (FOPH) were used for the observation of the bubble and for the pressure measurement, respectively. 1.1 MHz HIFU was utilized and a laser-induced bubble was generated at the focus of HIFU as a reflector bubble of HIFU. Cavitation inception occured due to the stronger negative pressure generated near a bubble by the backscattering of HIFU and the bubble cloud was formed along the opposite direction of HIFU propagation. The cavitation inception pressure has been evaluated as the pressure at the tip of the bubble cloud, which decreases with increase in water temperature. As a preliminary step to experiments using gelatin, the collapse of a laser-induced bubble near a gelatin-water interface has been observed. There was a large difference in the growth and shrink behaviors of bubble in gelatin and in water, and large bubble deformation was observed near the gelatin-water interface at maximum expansion. Also, the bubble translation became remarkable when the bubble collapses near the interface.