Dynamics of vortices and interfaces in superfluid 3He

TL;DR

This paper reviews recent advances in superfluid 3He hydrodynamics, focusing on vortex structures, phase boundary instabilities, turbulence transitions, and vortex propagation phenomena, based on experimental, numerical, and analytical studies.

Contribution

It provides a comprehensive review of new experimental and theoretical insights into vortex dynamics and interfaces in superfluid 3He, highlighting four key phenomena.

Findings

Observation of vortex structure interplay at 3He-A and 3He-B interface

Identification of superfluid Kelvin-Helmholtz instability

Transition from turbulent to regular vortex dynamics

Abstract

Rapid new developments have occurred in superfluid hydrodynamics since the discovery of a host of unusual phenomena which arise from the diverse structure and dynamics of quantized vortices in 3He superfluids. These have been studied in rotating flow with NMR measurements which at best provide an accurate mapping of the different types of topological defects in the superfluid order parameter field. Four observations are reviewed here: (1) the interplay of different vortex structures at the first order interface between the two major superfluid 3He phases, 3He-A and 3He-B; (2) the shear flow instability of this phase boundary, which is now known as the superfluid Kelvin-Helmholtz instability; (3) the hydrodynamic transition from turbulent to regular vortex dynamics as a function of increasing dissipation in vortex motion; and (4) the peculiar propagation of vortex lines in a long rotating column which even in the turbulent regime occurs in the form of a helically twisted vortex state behind a well-developed vortex front. The consequences and implications of these observations are discussed, as inferred from measurements, numerical calculations, and analytical work.