Propagation of Pulses of Second Sound in Liquid Helium II

Abstract

PRELIMINARY measurements of the velocity of second sound in this Laboratory using a resonator of fixed length and signals of a variable frequency have given results in good agreement with the resonance measurements of Peshkov¹ and of Lane, Fairbank and Fairbank². In the course of these experiments it became apparent that if measurements were to be extended below 1^° K., some method would be necessary which used a smaller mean power input. It can be shown, too, that the amplitude of temperature oscillation obtained in a resonance experiment is governed entirely by damping, and provides little information about the propagation of travelling waves in the medium.