Experiments on the twisted vortex state in superfluid 3He-B

TL;DR

This study combines experiments and simulations to investigate the dynamics of vortex lines in superfluid 3He-B, revealing how a twisted vortex state forms and relaxes, influenced by temperature and axial superfluid flow.

Contribution

It provides new insights into the formation, structure, and relaxation of twisted vortex states in superfluid 3He-B through combined experimental and numerical approaches.

Findings

Measured twist magnitude and relaxation rate as functions of temperature.

Demonstrated that axial superfluid flow sustains the vortex front.

Showed the twisted vortex state eventually relaxes to equilibrium.

Abstract

We have performed measurements and numerical simulations on a bundle of vortex lines which is expanding along a rotating column of initially vortex-free 3He-B. Expanding vortices form a propagating front: Within the front the superfluid is involved in rotation and behind the front the twisted vortex state forms, which eventually relaxes to the equilibrium vortex state. We have measured the magnitude of the twist and its relaxation rate as function of temperature above 0.3Tc. We also demonstrate that the integrity of the propagating vortex front results from axial superfluid flow, induced by the twist.