Possible nature of the dielectric activity of He II observed in experiments with second sound

TL;DR

This paper proposes a quantum-mechanical explanation for the electric signals observed in superfluid helium (He II) under second sound, attributing it to induced atomic dipoles and vortex ring fluxes, with implications for experimental measurements.

Contribution

It introduces a theoretical model linking atomic dipoles and vortex rings to observed electric signals in He II, explaining the dependence on resonator dimensions.

Findings

Electric signals in He II can be explained by induced atomic dipoles and vortex ring fluxes.

The voltage depends on resonator size, but experimental data suggests it may not be due to volume polarization.

Vortex rings may possess dipole moments of about ten atomic moments.

Abstract

An attempt is made to explain the nature of the electric signal observed in He II in a second-sound standing wave. Using the general quantum-mechanical principles, we show that, due to interatomic interaction, each atom of He-II acquires a small fluctuating induced dipole moment. A directed flux of microscopic vortex rings -- which, together with phonons, are thermal excitations of He II -- forms in the second-sound standing halfwave. This flux partially orders the chaotically oriented dipole moments of the atoms, which results in volume polarization of He II. The observed electric induction can be explained theoretically under the assumption that each vortex ring possesses a dipole moment of the order of ten atomic moments. It is shown also that the theoretical value of the voltage U induced in He II by the volume system of dipoles strongly depends on the dimensions of the resonator for dipoles of any origin. The experimental value of U is the same for two resonators of different size; therefore, this voltage may be not connected with the volume polarization of He II.