Full paper in PDF:
$% M. Schreiner, The dynamics of a levitated cylindrical permanent magnet above a
superconductor, Rev. Mat. Complut. 16 (2003), 495–517.%$
The Dynamics of a Levitated Cylindrical Permanent Magnet above a Superconductor
When a permanent magnet is released above a superconductor, it is levitated. This is due to the Meissner-effect, i.e. the repulsion of external magnetic fields within the superconductor. In experiments, an interesting behavior of the levitated magnet can be observed: it might start to oscillate with increasing amplitude and some magnets even reach a continuous rotation. In this paper we develop a mathematical model for this effect and identify by analytical methods as well with finite element simulations two reasons for the described behavior of the levitated magnet. It is shown, that the oscillations of the magnet are due to inhomogeneities of the magnetization within the magnet, whereas the continuous rotations are due to temperature gradients of the surrounding air.
Key words: superconductor, Meissner effect, levitated permanent magnet, rotating
permanent magnet.
2000 Mathematics Subject Classification: 82D55, 35K05, 37N20, 74H55.