Shape Effect of Magnetic Source on Stabilizing Range of Vertical Diamagnetic Levitation

This paper presents the results of a study on the shape effect of magnetic sources formed by standard coil and ring magnet elements on vertical diamagnetic levitation. The maximum stabilizing range, D_max, of a permanent-magnet floater levitated with the assistance of two diamagnetic graphite plates and powered with magnetic sources of different shapes was measured experimentally. The results were found to be well-correlated with theoretical data. The effectiveness of a shaped field source was determined by comparing its D_max to that of a single standard coil equivalent with the same total thickness, turns, and applied current. For the permanent magnetic sources, the comparison was to a single ring magnet of the same total thickness, volume, and residual flux. The results indicate that a cone-shaped source of either electromagnet or permanent magnet has positive effects. Theoretical analyses suggest that acquiring a levitation position farther from the magnetic source and a smaller magnitude in B^´´ are significant in obtaining a larger stabilizing range.