Dissipation of Quantum Turbulence in the Zero Temperature Limit

TL;DR

This study investigates how quantum turbulence in superfluid helium dissipates at near-zero temperatures, revealing decay patterns and an effective viscosity that suggest quasi-classical turbulence behavior.

Contribution

It provides the first detailed measurement of vortex line density decay and effective viscosity in superfluid helium at temperatures approaching absolute zero.

Findings

Vortex line density decays as t^(-3/2)

Energy flux scales as t^(-3)

Effective viscosity at zero temperature is 0.003 kappa

Abstract

Turbulence, produced by an impulsive spin-down from angular velocity Omega to rest of a cube-shaped container, is investigated in superfluid 4He at temperatures 0.08 K - 1.6 K. The density of quantized vortex lines L is measured by scattering negative ions. Homogeneous turbulence develops after time t of approximately 20 \Omega and decays as L proportional to t^(-3/2). The corresponding energy flux epsilon = nu' (kappa L)^2, which is proportional to t^(-3), is characteristic of quasi-classical turbulence at high Re with a saturated energy-containing length. The effective kinematic viscosity in the T=0 limit is nu' = 0.003 kappa, where kappa=10^(-3) cm^2 / s is the circulation quantum.