Effects of Dimensions in Added Ring-Shaped Magnet on Superconducting Levitation

The flux pinning effect of bulk superconductors facilitates noncontact stable levitation of permanent magnets without any active control. In this study, a levitation system using a bulk superconductor was supplemented with a hybrid stator having a ring-shaped magnet in order to improve the stability of the superconducting levitation. Further, the effect of the size of the inner diameter of the ring-shaped magnet on the levitation stability was elucidated by measuring the levitation characteristics of a levitating magnet located above the hybrid stator to ring-shaped magnets with a variety of inner diameters. The vertical magnetic stiffness was improved only for 25-mm inner diameter, and the stiffness decreased if the diameter was larger or smaller than 25-mm. The horizontal magnetic stiffness decreased at the initial position, but the range expanded for which the restoring force acted. The results show that by the appropriate selection of the inner diameter of the ring-shaped magnet, the performance of the hybrid stator can be maximized.