Transmission of sound at the liquid-solid interface of helium : a new probe of melting kinetics

Abstract

An incoming acoustic wave produces an a.c. discontinuity of chemical potential, Δ μ at a liquid-solid interface. If melting is fast enough, it responds to such an excitation. We show that in quantum systems, in which heat can be evacuated via convection, such an a.c. melting does occur. It may give rise to a spectacular decrease in sound transmission, and to a conversion mechanism from first to second sound. We analyse that effect, and we propose an experiment that should give access to the kinetics of melting when it is too fast to be observed by d.c. methods