Rotational decay torques of superconducting magnetic bearing

A superconducting magnetic bearing is proposed as one of the applications of a high-critical-temperature (T/sub c/) oxide superconducting material. New models of bearings with a free rotation axis were assembled. In these models, the superconductor, YBa/sub 2/Cu/sub 3/O/sub x/, prepared by the quench and melt growth (QMG) method, was applied to the bearing section and a permanent magnet was used for a rotor. This development originated from the knowledge that YBa/sub 2/Cu/sub 3/O/sub x/ prepared by the QMG method has a stronger pinning force for magnetic flux than that of conventional superconductors. A study of the forces and the damping for magnet rotation above the QMG superconductor was also made. It showed that levitation force and lateral force due to flux pinning were extremely large and damping for magnet rotation was small.