Damping of mechanical vibration by superconducting Y B a 2 C u 3 O 7− x in a magnetic field

As the load capacity of magnetic bearings using high-Tc superconductors increases, the inherent damping decreases. Damping of externally generated vibration is an important unsolved problem. A proposal is made for an active damping system, based upon the strong temperature dependence of the magnetic flux dissipation in a high-Tc superconductor in the region of the phase transformation a few degrees below the transition temperature. The damping system would be distinct from the levitated system. The strong temperature dependence of the dissipation is demonstrated with a single crystal of yttrium barium copper oxide, but a melt-processed ceramic sample would behave in the same way.