Lateral Damping in a Magnet-High TcSC System

The properties shown by a magnet levitating above a high Tc superconductor pellet can lead to use them in magnetic bearings or other applications such as coupling devices or dampers. The levitation properties and the static stability are well demonstrated but it is not clear if their damping properties are sufficient for applications to avoid any active damping device. The work presented here studies the damping of the oscillations of a magnet above a superconducting pellet, in a pendulum device where displacements and forces are simultaneously measured. Magnet and superconducting pellet dimensions are of the same order. The pulsation of the harmonic motion is governed by the static lateral forces but the damping seems to be dependent on the initial amplitudes. In our configuration, even for the first oscillations, the damping is less efficient than with copper at 77 K, and the small oscillations are quite undamped