Levitation force characteristics of magnetic levitation type seismic isolation device composed of radial arrangement of HTS bulks and permanent magnets

This paper proposed a magnetic levitation type seismic isolation device composed of radial arrangements of High Temperature Superconducting (HTS) bulks and Permanent Magnets (PM). We first analyzed and compared the levitation force of an axial arrangement and radial arrangement of the HTS bulk and PM rail for the seismic isolation device, respectively. Due to Halbach arrangement of the PM rail, the radial type HTS seismic isolation device can provide a comparable levitation force to the conventional axial type device. We also investigated the dependence of the levitation force on the shape of the HTS bulk and PM rail to clarify the design guidelines of the radial type device. The analysis results showed that a thinner HTS bulk generated a larger levitation force per unit volume of the HTS bulk. The analysis also clarified the proper bulk width by considering the magnetic flux density distribution of the Halbach PM rail. We also found that increasing the volume of the PM rail does not greatly improve the levitation force of the radial type device. These results suggest that the levitation force of the radial type HTS seismic isolation device can be most effectively increased by arranging several thin HTS bulks in the longitudinal direction of the PM rails.