Electric polarization of He II caused by second and first sound

Abstract

It is shown that in a three-component gas of superfluid helium (He II) quasiparticles made up of phonons, rotons, and quantized vortex rings (QVR), equilibrium is established instantaneously on experimental time scales. This results in the formation of a common normal component which can move relative to the superfluid component with a velocity w. When a velocity w is present, an electric field develops in the He II that has been observed experimentally. The reasons for this are an anisotropic dependence of the QVR energy on its momentum when w is present and the existence of a QVR dipole moment. The case where the dipole moment of a QVR is made up of its intrinsic dipole moment plus the dipole moment created by an external field is considered. The problem of the electric potential in a standing wave of second sound in a constant external electric field is solved. The electric potentials in a first sound wave owing to the flexoelectric effect, acceleration of the liquid, and an external electric field are obtained. These formulas are used in numerical calculations for comparing theory and experiments, and they can stimulate the setting up of new experiments.