Novel high-field permanent-magnet flux sources

Several compact permanent-magnet configurations are discussed which produce fields greater than the remanence of the magnetic material comprising them. For example, a field of 20 kG can be produced in a one-inch diameter spherical cavity by a NdFeB sphere of 12 kG remanence and 3.5 inch diameter. Field perturbation due to access holes in the structure are analyzed by finite element methods, and their effects on device utility are discussed.