Bubble nucleation in a superfluid ³He–⁴He mixture induced by acoustic wave

摘要

We report the nucleation dynamics of bubbles induced by an acoustic wave pulse in ³He–⁴He liquid mixtures.udThe experiment was performed for the mixture with ³He fixed concentrations of about 4% and 25%udand the pure superfluid ⁴He. When a pulse of 1 ms duration was applied to the mixture at the saturated vaporudpressure, a spherical bubble was nucleated on the active area of a piezoelectric transducer. For the case ofudpure ⁴He, not a spherically shaped bubble, but an irregularly shaped, larger one was observed. We took picturesudwith a high speed CCD camera of the bubble expansion and contraction motions after the nucleation.udWe also investigated the temperature dependence of the bubble nucleation by changing the acoustic waveudpower. The results show that the nucleation and growth dynamics of a cavitation bubble depend greatly onudthe ³He concentration and temperature.