Stability of magnets levitated above superconductors
- 15 October 1988
- journal article
- research article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 64 (8) , 4212-4218
- https://doi.org/10.1063/1.341312
Abstract
The stability of a permanent magnet levitated above a slab of hard superconductor is considered. The force on a dipole magnet over a perfectly diamagnetic disk is calculated. It is found that the radial component of the force is directed outward and is 10%–20% of the image (vertical) force near the edge. Estimates of the magnetic friction force due to flux motion in a hard superconductor are made using Bean’s model. The magnitude of the magnetic friction is large enough to stabilize the magnet over most of the disk for typical values of the critical current in ceramic superconductors (∼103 A/cm2), but too small for the highest values reported (>106 A/cm2). It is conjectured that flux trapping due to inhomogeneities gives rise to transient restoring forces.This publication has 10 references indexed in Scilit:
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