Twisted vortex state
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.
Movies of twisted vortices
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
Publications
- V.B. Eltsov, A.P. Finne, R. Hänninen, J. Kopu, M. Krusius,
M. Tsubota and E.V. Thuneberg: Twisted vortex state,
Phys. Rev. Lett. 96, 215302 (2006),
cond-mat/0602667.
- J. M. Karimäki, R. Hänninen and E.V. Thuneberg:
Asymptotic motion of a single vortex in a rotating cylinder,
Phys. Rev. B 85, 224519 (2012).
- Transparencies of a talk:
Twisted vortex state
(April 2007, E. Thuneberg, pdf file, 842 kb).
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12.4.2013, Erkki Thuneberg, Email
