Angular-Momentum Experiments with Liquid Helium

Abstract

Angular-momentum measurements on helium I and helium II contained in a cylindrical vessel suspended from a virtually frictionless magnetic bearing are reported. Helium I behaves as a classical viscous fluid but the results for helium II are quite different. The latter shows two distinct types of behavior, either assuming an equilibrium state of solid-body-type rotation or else forming a metastable state wherein the liquid refuses to be excited into rotation. Both types of behavior are shown to be in accordance with predictions of the Onsager-Feynman hypothesis of quantized circulation in the superfluid. Data are presented which seem to imply that macroscopic turbulence already present in the superfluid is a necessary condition for the generation of quantized vortex lines in this type of geometry.