Three dimensionality of pulsed second-sound waves in He II

TL;DR

This study investigates the three-dimensional propagation of pulsed second sound waves in superfluid helium (He II), combining experimental measurements with theoretical modeling to understand effects like heater size, vortex interactions, and boundary layer formation.

Contribution

It provides a comprehensive experimental and theoretical analysis of 3D pulsed second sound waves in He II, highlighting the influence of heater size and vortex dynamics on wave behavior.

Findings

Heater size significantly affects second sound wave profiles.

Inverse counterflow occurs during rarefaction of the wave.

Dense vortex accumulation leads to thermal boundary layer formation.

Abstract

Three dimensionality of 3D pulsed second sound wave in He II emitted from a finite size heater is experimentally investigated and theoretically studied based on two-fluid model in this study. The detailed propagation of 3D pulsed second sound wave is presented and reasonable agreement between the experimental and theoretical results is obtained. Heater size has a big influence on the profile of 3D second sound wave. The counterflow between the superfluid and normal fluid components becomes inverse in the rarefaction of 3D second sound wave. The amplitude of rarefaction decreases due to the interaction between second sound wave and quantized vortices, which explains the experimental results about second sound wave near [Phys. Rev. Lett. 73, 2480 (1994)]. The accumulation of dense quantized vortices in the vicinity of heater surface leads to the formation of a thermal boundary layer, and further increase of heating duration results in the occurrence of boiling phenomena. PACS numbers: 67.40.Pm 43.25.+y 67.40.Bz