Superconducting permanent magnets

Conference · Wed Mar 01 04:00:00 EST 1989 · IEEE Trans. Magn.; (United States)

OSTI ID:5918591

Wipf, S L; Laquer, H L

The concept of superconducting permanent magnets with fields trapped in shells or cylinders of Type II superconductors is an old one. Unfortunately, the low values of 0.5 to 1T for the first flux jump field, which is independent of the actual current density, have frustrated its implementation with classical Type II superconductors. The fact that the flux jump fields for high temperature superconductors should be an order of magnitude larger at liquid nitrogen temperatures allows us to reconsider these options. Analysis of the hysteresis patterns, based on the critical state model, shows that, if the dimensions are chosen so that the sample is penetrated at a field B/sub p/, which is equal to or just less than the first flux jump field, B/sub fj/, a temporarily applied field of 2B/sub fj/ will trap 0.5 B/sub fj/. Thus for a 90 K superconductor with a B/sub fj/ of 6T, a permanent field of 3 T should be trapped, with an energy product of 1.8 MJ/m/sup 3/ (225 MG . Oe). This is five times as large as for the best permanent magnet materials. The authors discuss means to verify the analysis and the limitations imposed by the low critical current densities in presently available high temperature superconductors.

• Research Organization: CryoPower Associates, Los Alamos, NM (US)
• OSTI ID: 5918591
• Report Number(s): CONF-880812-
• Conference Information: Journal Name: IEEE Trans. Magn.; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CRITICAL CURRENT
CURRENT DENSITY
CURRENTS
DATA ANALYSIS
DESIGN
ELECTRIC CURRENTS
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
ELEMENTS
EQUIPMENT
HIGH TEMPERATURE
HYSTERESIS
MAGNETIC FLUX
MAGNETS
NITROGEN
NONMETALS
PERFORMANCE
PERMANENT MAGNETS
SUPERCONDUCTING DEVICES
SUPERCONDUCTING MAGNETS
TRAPPING