Dynamics and relaxation of magnetic stress between magnet and superconductor in a levitation system

The force of levitation experienced by a magnet on top of a superconductor depends on position and how fast the magnet was put into that position. As a result, when the levitation force is measured as a function of the height of the magnet above the superconductor, a plot of the force versus height also depends on the rate at which the magnet position was changed during the experiment. The authors have measured this dependence of the levitation force (as a function of position) on the average rate of moving the magnet towards the superconductor under zero field cooled conditions. This dependence is appreciable only when the magnet is close to the superconductor. After the magnet is brought to a stop at the nearest position, they continued to observe the relaxation of the magnetic stress between the magnet and the superconductor. The gross characteristics of the relaxation process after the magnet stops are similar for different speeds of approach before the magnet stops. This study aims at determining how the long term reliability of a superconductor magnet bearing depend on the process of setting it up.