Flux distribution in multiaperture ferrite cores

This paper describes a technique of determining the internal flux distribution in a multiaperture core by mapping the fringing magnetic fields in the vicinity of surface discontinuities, which are introduced into the core face by partially slitting the core. The field mapping device employed is a high-resolution Hall probe, used in conjunction with a chopper amplifier and a phase-sensitive detector. By mapping the component of magnetic field normal to the core face in the region of the slot, a characteristic field pattern dependent upon the direction of flux in the core is observed. In regions of reversal of the internal flux, there is a corresponding reversal in the characteristic field pattern. The boundary separating regions of opposite magnetization in a partially switched core has been defined to within 20 microns. Data are presented showing typical fringing field patterns observed for totally switched and partially switched cores.