An equivalent circuit approach to the solution of static electromagnetic forces in a mixed-mu levitator

Mixed-mu levitation is the principle whereby iron is levitated in a magnetic field and stabilised by the proximity of diamagnetic superconducting screens. This paper is concerned with the 3D modelling of such systems so that approximate but fast force solutions can be obtained for various geometries within a basic levitator design. The iron and superconducting screens are modelled by equivalent circuit elements for which general force expressions can be derived analytically. For a basic levitator design, a fast interactive program is written to compute these forces for various geometries. Results are compared both with experiment and with those obtained from large 2D and 3D finite element magnetostatic packages. Good agreement is obtained.