Numerical Optimization for Magnetic Force Field Enhancement on Superconducting Coils

Abstract

High magnetic force field plays an important role in the wide applications of magnetic processing such as magnetic separation of ferromagnetic materials and magnetic levitation of diamagnetic materials. Therefore, the research on magnetic force field enhancement has been becoming a popular subject recent years. Many experimental methods have been designed and applied to enhance magnetic force field, however those methods took higher costs and longer time to set up real installations. A numerical optimization method was developed, which used only superconducting coils to calculate a magnetic force field and maximize it. In the method, the magnetic flux density $B$, the magnetic field gradient $\grad B$ and the magnetic force field $\grad (B^{2}/2)$, as objective functions respectively, were maximized with constraints of the total volumes of coils and the $B$-$J$ characteristics of superconductors. By comparing the numerical optimization results with theoretical values for single coil, we found that they are in good agreement. Also, in comparison with the results obtained by random models for double coils, those by optimal models were better. Moreover, the maximal magnetic force field was higher remarkably than that generated by the previous optimal model in NIMS.