Magnetic field penetration into thin discs

Abstract

An integro-differential equation is established for the azimuthal eddy current in a thin circular disc. The decay of the eddy current formed when a uniform magnetic field is applied across the disc is obtained as an expansion in exponentially decaying eigenmodes. The method is generalised to a pair of coaxial discs, enabling the measured field penetration into the end-plates of a rotamak to be reproduced.