Levitation of a Soft Magnetic Sphere in a Field of Superconducting Coils Simulating an Axially Magnetic Torus

Abstract

The ponderomotive forces affecting a soft magnetic sphere in a field of superconducting coaxial coils geometrically simulating a torus are investigated. To determine the forces, we used a mathematical model for the fields produced by an axially magnetized torus. The model includes calculating the polarization of the sphere with the averaging of the surface magnetic charges in two hemispheres and determining the forces affecting the effective magnetic charges of the hemispheres located in their centers of gravity. Thus, the model was reduced to a one-dimensional one. The calculations take into account the magnetic saturation of the sphere. The correctness of the dipole approximation of the calculation of the forces is shown. A correlation between the coordinates of the center of the sphere and the characteristic coordinates of the torus field was established. The areas of the stable equilibrium of the sphere are calculated. The applicability of the model is determined. The results of the calculations are compared with the experimental data.