Characteristics of a superconducting magnetic bearing

Both repulsive and attractive forces caused by the pinning state in which the magnetic field is trapped in a superconductor are capable of noncontact steady support of an object in all directions. In this paper, we describe the levitation force characteristics, the force relaxation caused by flux creep, and the bearing loss under high rotational speed, of a disk-type superconducting bearing at a temperature of 77 K, as well as the rotational characteristics of pinning-type superconducting radial bearings. The bearing consists of Y 1 Ba 2 Cu 3 O x (YBCO) oxide superconductors fabricated using quench melt growth(QMG) process and rare-earth permanent magnets. The rotor in which a permanent magnet is supported by the pinning force in the superconductor can be safely operated at high rotational speeds.