Melt textured YBCO samples for trapped field magnets and levitating bearings

摘要

Bulk melt textured YBCO materials in the shape of disks are being developed for use as trapped field magnets and in superconducting bearings. The trapped field in the gap between two disks of 26 mm in diameter reached maximum values of 1 T at 77 K and of 8.5 T at 51.5 K. A superconducting magnetic bearing has been built up of two YBCO rings and two concentric NdFeB ring magnets between them. A static levitation force of 25 N and values of the axial and radial stiffnesses of 15 N/mm and 10 N/mm, respectively, have been achieved for this bearing in the working position. A high speed motor with two superconducting magnetic bearings of this kind has been tested at 77 K.