The permeability of composite magnets formed by regular arrays of steel spheres in air

Abstract

The relationship between the relative permeability of an isolated sphere and that of an array of such spheres is investigated. An integrated treatment of the historical theoretical work for both general and specifically regular arrangements is presented. Experimental values of the permeabilities are determined using solenoidal-ballistic methods. Experimental values for the array permeabilities emphasise the necessity of an optimum measuring cell. Considerable agreement between theory and experiment is found, two significant factors of sphere permeability and composite magnet macroscopicity being discussed.