Dynamic characteristics of a high-<i>T</i> <i>c</i> superconducting bearing with a set of alternating-polarity magnets

Abstract

Dynamics of a superconducting bearing with a high-Tc superconductor and a set of alternating-polarity magnets are discussed. The superconductor used is prepared by the quench and melt growth process. The set of magnets levitates over the superconductor which is field cooled in liquid nitrogen. To construct a dynamic model of the superconducting bearing, responses for impulse forces given to the levitating magnets in vertical direction are investigated. Damped free-vibration curves of the levitating magnets are observed. Dynamic stiffness and viscous damping coefficient can be defined by using the periodical vibration curves. It is also found that the stiffness and the damping coefficient depend on the width of a bar magnet. The resultant energy loss of the superconducting bearing is evaluated by using the force-displacement relationship and Bean’s critical state model [Phys. Rev. Lett. 8, 250 (1962)].