Development of superconducting magnetic bearings

Abstract

The interaction between high temperature superconductors (HTS) and permanent magnets allows to realize an inherently stable contactless bearing without active feedback system. It has no wear, very low friction and allows operation at high rotational speed. Its thermal inertia prevents a sudden breakdown. High magnetic gradient bearings with a special magnet configuration work both radially and axially. We have designed and constructed a test set-up with two HTS journal type bearings. Investigation of characteristic bearing features was performed in quasi-static experiments with different YBCO stators. Stiffness of the bearings and the dependence of losses per force–displacement cycle on the amplitude were characterized. Losses per force–displacement cycle were investigated in dynamic measurements with frequencies between 0.01 and 40 Hz and resulted in nearly frequency independent behaviour.