The absorption of sound in liquid helium II

Abstract

The absorption of sound in liquid helium II has been measured in the temperature range down to 0$\cdot $4 degrees K, at frequencies of 6$\cdot $0 and 14$\cdot $4 Mc, and under pressures of up to 25 atm. The results are compared with the theory of Khalatnikov (1950, 1952). Besides accounting for the existence of a maximum in the absorption-temperature curve, this theory predicts the manner in which the magnitude and position of the maximum varies with frequency, and with pressure. It is shown that these predictions are qualitatively correct, although exact numerical agreement is not obtained. The measurements also confirm the observations of Chase & Herlin (1955) that the absorption at the lower temperatures is greater than that to be expected from Khalatnikov's original treatment. It seems that the additional absorption may arise from processes associated with the kinetic coefficient of thermal transport (Khalatnikov 1952).