Theoretic and numerical analysis of diamagnetic levitation and its experimental verification

Abstract

Diamagnetic levitation system is studied in detail in this paper. From top to bottom, the diamagnetic levitation system is composed of a lifting magnet, a top pyrolytic graphite sheet, a floating magnet and a bottom pyrolytic graphite sheet. The gravity of the floating magnet is balanced by the attractive force between the lifting magnet and the floating magnet. And the floating magnet is stably levitated between the top and bottom graphite sheets due to their diamagnetism. The force exerted on the floating magnet is analyzed through theoretical and numerical methods, and at the same time the equilibrium position is obtained. Totally 11 groups of magnets are studied by COMSOL, in which the accumulative error is eliminated to improve the accuracy of finite element analysis(FEA). Corresponding experiments are carried out to verify the numerical results, and the error of equilibrium position is less than 10%, which shows that the FEA is precise enough to simulate the diamagnetic system. Motion characteristic is studied for group 6, in which the lifting magnet is a φ3/16”× 1/8” cylinder. For the floating magnet, the horizontal force versus the eccentric displacement and the vertical force versus the vertical displacement are calculated by COMSOL respectively. In the magnetic potential well of the lifting magnet, the floating magnet returns to the vertical central axis automatically, and the frequencies of the vertical and horizontal movements are between 4 and 5 Hz. The frequencies of the two directional movements can be tuned by the magnetic parameters of the lifting and floating magnets and the structure dimensions of the system. The method used to analyze the diamagnetic system is proved effective to design the diamagnetic levitation structure. Because of the contactless levitation of the floating magnet based on diamagnetism, the system is sensitive to very small input. This diamagnetic levitation structure is potential in micro-actuators and sensors.