Chapter 3 Quantum Turbulence in Superfluid 3He at Very Low Temperatures

Abstract

Abstract Turbulence is a very complex motion of a fluid which occurs at sufficiently high flow rates in a wide range of physical systems and has far-reaching technological implications. Although the underlying equations of fluid dynamics are well known, a comprehensive theoretical description of turbulence is a major unresolved problem of classical physics. A better understanding of turbulence might be gained by investigating systems which offer simplifications. Quantum turbulence is represented by the seemingly complex dynamics of a tangle of quantised vortex lines in a superfluid. At very low temperatures, there is no normal fluid component and therefore no associated viscosity. These are very simple conditions, both from conceptual and mathematical view points. We have recently developed techniques for detecting quantum turbulence in superfluid 3 He-B in the low temperature limit. We use quasiparticle excitations to directly probe the superfluid flow field. We describe various experiments investigating the production, evolution and decay of quantum turbulence. The results obtained give the first empirical steps towards addressing a number of interesting questions, such as how closely does quantum turbulence resemble classical turbulence and how does quantum turbulence decay in the absence of the viscous dissipation.