Polarization phenomena in nickel-iron alloys, and their effective elimination

The mathematical results of Butler and Mangl are utilized to determine the distribution of the flux density in ferromagnetic laminae at various instants. The manner in which the phenomenon of polarization in opposite directions occurs at the outer and inner parts of nickel-iron laminae is clearly demonstrated for power-and audio-frequency operation. The mathematics is extended to enable the distribution of harmonic magnetization in the laminae to be determined. It is shown that harmonic magnetization occurs in the laminae even when the total flux does not contain harmonics. The calculated results afford an explanation of the difficulties encountered in attempts to demagnetize nickel-iron alloys completely, and assist the development of a reliable method of demagnetization. It is shown that methods that have been applied successfully to silicon-iron alloys, and tacitly accepted for nickel-iron alloys, possess inherent defects in the latter case.