Consider superfluid in a long cylindrical container. The container is rotating around its axis, but we assume that there are no vortices in the initial state. If vortices are then generated at one end, they start to propagate along the cylinder. Simultaneously the vortex ends rotate around the cylinder axis. For the propagating ends this rotation is slower than for the equilibrium vortex lattice, which tends to rotate at the same angular velocity as the container. This creates a twisted vortex state, as shown in the figure.
In the publication we present simple arguments for the difference in the rotation velocity. We construct a continuum theory for the twist and find equations governing the untwisting. The twisted state gives rise to axial supercurrents. We report experimental evidence of the twisted state observed by NMR in superfluid 3He. Although not all details are understood, the measured relaxation time of the twisted state is in agreement with theoretical calculations.
The figure on this page is a snapshot of the evolution of the vortex state. The whole evolution is shown in the following movie: twist with 23 vortices (3.4M). All movies are based on accurate numerical solution of the vortex equations of motion.
In addition to vortices, the following movie shows also the axial and azimuthal counterflow velocities: axial and azimuthal velocities (5.3M).
More movies of twisted vortices
Back to helium theory page12.4.2013, Erkki Thuneberg, Email