Vortex Multiplication in Applied Flow: the Precursor to Superfluid Turbulence

TL;DR

This paper investigates the behavior of quantized vortices in superfluid helium-3, revealing a temperature-dependent transition from stable vortex configurations to vortex multiplication leading to turbulence, supported by experimental and numerical analysis.

Contribution

It identifies a temperature-driven transition in vortex dynamics and proposes a mechanism for vortex multiplication at low temperatures in superfluid helium-3.

Findings

Vortex number remains constant above 0.5 T_c

Below 0.5 T_c, vortex number increases linearly over time

Mutual friction parameter influences vortex formation and turbulence onset

Abstract

The dynamics of quantized vortices in rotating $^3$He-B is investigated in the low density (single-vortex) regime as a function of temperature. An abrupt transition is observed at $0.5 T_{\rm c}$. Above this temperature the number of vortex lines remains constant, as they evolve to their equilibrium positions. Below this temperature the number of vortices increases linearly in time until the vortex density has grown sufficiently for turbulence to switch on. On the basis of numerical calculations we suggest a mechanism responsible for vortex formation at low temperatures and identify the mutual friction parameter which governs its abrupt temperature dependence.