Lateral force in permanent magnet-superconductor levitation systems with high critical current

The force generated when a zero-field-cooled superconductor is displaced laterally from an initially cylindrically symmetric situation is numerically calculated. An unstabilizing lateral force, according to previous measurements, is obtained. Approximate analytical expressions for both lateral and vertical force are also presented for small lateral displacements. In this case, it is concluded that the lateral stiffness is independent of the lateral disturbance, whereas the cross-stiffness is zero.