Stability of magnets levitated above superconductors

Journal Article · Sat Oct 15 04:00:00 EDT 1988 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.341312· OSTI ID:7086367

Davis, L C; Logothetis, E M; Soltis, R E

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 (approx.10/sup 3/ A/cm/sup 2/), but too small for the highest values reported (>10/sup 6/ A/cm/sup 2/). It is conjectured that flux trapping due to inhomogeneities gives rise to transient restoring forces.

• Research Organization: Research Staff, Ford Motor Co., Dearborn, Michigan 48121-2053
• OSTI ID: 7086367
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 64:8; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
420201* -- Engineering-- Cryogenic Equipment & Devices
656100 -- Condensed Matter Physics-- Superconductivity
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL CURRENT
CURRENTS
ELECTRIC CURRENTS
LEVITATION
MAGNETIC FLUX
MAGNETS
OXIDES
OXYGEN COMPOUNDS
STABILITY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES