Dramatic effect of superfluidity on the collapse of He 4 vapor bubbles

The lifetime of cavitation bubbles produced by an acoustic wave focused in liquid helium-4 is investigated. This lifetime is found to be different by orders of magnitude depending on whether the liquid is superfluid or not. We show that if the liquid is in the superfluid state, the bubble lifetime is well explained by a purely mechanical model, corresponding to the so-called Rayleigh regime. In the normal state, the Rayleigh-Plesset regime applies, in which heat diffusion plays a crucial role and dramatically increases the bubble lifetime.