Characteristics of a Superconducting Magnetic Bearing.

Both repulsive and attractive forces caused by the pinning state where a magnetic field is trapped in a superconductor are capable of noncontact steady support of an object in all directions. This paper describes the characteristics of the levitation forces, the force relaxation caused by the flux creep and the bearing loss under high rotational speed on a disc-type superconducting bearing at 77K, as well as the rotational characteristics of the pinning-type superconducting radial bearings. The bearing consists of Y1Ba2Cu3Ox(YBCO) oxide superconductors fabricated by the QMG (quench-melt-growth) process and rare-earth permanent magnets. The rotor with permanent magnets supported by the pinning force in the superconductor can be safely operated under high rotational speed.