高強度集束音場中での気泡核の成長と安定性に関する解析.

The growth of bubble nuclei in high intensity focused ultrasound (HIFU) is investigated. The imposed pressure on the nuclei is given by the experiments for the backscattering of HIFU from a laser-induced bubble interface. The lower limit of initial radius, R_omin over which the bubble grows explosively, is calculated using the dynamical equation of motion for a spherical bubble in which the liquid compressibility and the thermal diffusion through the bubble interface are taken into consideration. The relationship between R_omin and the absolute value of the minimum of imposed pressure |P_min| is obtained for various temperature ranges. It is shown that temperature dependency of |P_min| is in good agreement with that obtained directly from the corresponding experiments. It is also shown that appropriate choice of physical properties makes it possible to predict the relationship between R_omin and |P_min| in a temperature range from that in different temperature ranges even though the imposed pressure on the nuclei is different with each other. The results also show that temperature dependency of surface tension is a key factor to determine R_omin. [ABSTRACT FROM AUTHOR]