The dynamics of vortex generation in superfluid 3He-B

TL;DR

This paper investigates how quantized vortices in superfluid 3He-B become unstable and generate turbulence at low temperatures, using NMR measurements and numerical calculations to understand the wall-triggered vortex instability.

Contribution

It provides experimental evidence and interpretation of vortex instability mechanisms in superfluid 3He-B at intermediate temperatures, highlighting the role of wall interactions.

Findings

Vortex instability occurs at the container wall.

The instability leads to vortex loop generation.

Temperature influences vortex damping and stability.

Abstract

A profound change occurs in the stability of quantized vortices in externally applied flow of superfluid 3He-B at temperatures ~ 0.6 Tc, owing to the rapidly decreasing damping in vortex motion with decreasing temperature. At low damping an evolving vortex may become unstable and generate a new independent vortex loop. This single-vortex instability is the generic precursor to turbulence. We investigate the instability with non-invasive NMR measurements on a rotating cylindrical sample in the intermediate temperature regime (0.3 - 0.6) Tc. From comparisons with numerical calculations we interpret that the instability occurs at the container wall, when the vortex end moves along the wall in applied flow.