Magnetic interaction force between high-Tc superconductor-ring and magnet

The magnetic interaction force between superconducting ring and cylindrical permanent magnets of different lengths, aligned coaxially, has been investigated experimentally at zero-field-cooled and field-cooled conditions. The force as a function of the position of the magnet relative to the superconductor ring is qualitatively that expected if the superconductor is regarded as a diamagnet with nonohmic dissipation. The hysteretic behavior of the axial force component was studied. It is shown that the size of the hysteresis loop grows with the strength of the magnet in general, but the shape of the loop also undergoes complicated changes. It was found that field-cooled conditions can yield a higher support force in this permanent magnet and superconducting ring system, with lower hysteresis loss. This makes this system an attractive candidate for a low loss magnetic journal bearing.