Anomalous vortex ring velocities induced by thermally-excited Kelvin waves and counterflow effects in superfluids

TL;DR

This paper investigates how thermal excitations and counterflow effects influence vortex ring velocities in superfluids, revealing a temperature-dependent slowdown caused by Kelvin waves, with implications for Bose-Einstein condensates and helium superfluids.

Contribution

It demonstrates the impact of thermally excited Kelvin waves on vortex dynamics and quantifies this effect across different superfluid systems.

Findings

Vortex rings slow down anomalously at higher temperatures.

Counterflow induces vortex dilatation and mutual friction effects.

The temperature-dependent slowdown is estimated using energy equipartition.

Abstract

Dynamical counterflow effects on vortex evolution under the truncated Gross-Pitaevskii equation are investigated. Standard longitudinal mutual friction effects are produced and a dilatation of vortex rings is obtained at large counterflow. A strong temperature-dependent anomalous slowdown of vortex rings is observed and attributed to the presence of thermally exited Kelvin waves. This generic effect of finite-temperature superfluids is estimated using energy equipartition and orders of magnitude are given for weakly interacting Bose-Einstein condensates and superfluid $^4{\rm He}$.