The effect of the sound modes on the quantum nucleation in a supersaturated superfluid 3He– 4He mixture

Abstract

The quantum nucleation of a droplet of the 3He-concentrated phase in a supersaturated superfluid 3He– 4He mixture is analyzed. The emission of the first and second sound modes, which accompanies the growth of the 3He-concentrated droplet, is incorporated into the calculation of the quantum nucleation rate under assumption of an arbitrary boundary condition for the normal velocity at the interface surface. The total intensity of the sound emission with an expanding droplet is found to be predominant due to the smallness of the second sound velocity compared with the velocity of the first sound in the superfluid 3He-dilute phase. As compared with the calculations based on the dissipationless models with the infinite sound velocity, the sound emission, resulted from the finiteness of the sound velocities, facilitates the quantum nucleation. The relative enhancement for the logarithm of the nucleation rate is about (Δ x) 1/2 where Δ x is the supersaturation of a mixture. The latter is in contrast to the viscous dissipative processes which are known to hinder the quantum nucleation.