磁性流体を吸着した永久磁石の超伝導浮上における振動減衰

抄録

   Superconducting oscillation having a relatively small amplitude continued for a long time, unlike the linear damping oscillation of a typical viscosity. This research is conducted to investigate the changes in periodic damping for a levitated magnet by encompassing a levitated magnet with a magnetic fluid for the purpose of suppressing oscillations, in order to optimally use the advantages of levitating superconductors. Damping oscillation of a permanent magnet encompassed with magnetic fluid above a high temperature superconductor was measured using a laser displacement meter. The oscillation of the magnet encompassed with the magnetic fluid subsided in a significantly shorter time than the oscillation obtained in the case when only the magnet was used. Furthermore, the oscillation was faster converge than when the same amount was in a solid state (frozen magnetic fluid). These results confirmed that damping occurred because of the fluidity and the viscosity of the magnetic fluid. A comparison of the waveform of the magnet encompassed with the magnetic fluid and the calculated waveform of the linear oscillation revealed that they were almost identical. It was clear that the properties changed to something different as compared to the damping properties in the case when losses occurred from the pinning effect, because of the magnetic fluid.