Novel application of high T_c bulk superconductors

Large persistent currents can flow in the superconductors when they exhibit a large pinning force. The interaction between such persistent currents and magnetic field gives both repulsive and attractive forces. Various applications are now under consideration using such interaction, e.g., magnetic bearing, flywheel, transport system. The pinned superconductor can also either shield or trap magnetic fields by persistne currents. Magnetic shield and superconducting permanent magnets can be made using such properties.