A sector type of an ordinary electromagnet with iron pole pieces has been fabricated in such a way as to suppress mechanical inhomogeneities in the magnetic fields.
To a measuring precision of 1 part in 104, the important sources of field inhomogeneities along a radial direction in the pole pieces with a sharp-cutoff profile are concluded to be the saturation and the difference between the leakage fluxes in the curved pole-piece sides with the smaller and the larger radii of curvatures which is due to the magnetic asymmetry along the radial direction of the geometry of pole pieces in the lower field region, and the saturation in the higher field region. The field inhomogeneities in the radial direction do not reveal differences associated with the field-setting procedure of the magnetization-demagnetization and resulting from the iron material of pole pieces.
In the magnet performance the effect of the field homogenizers is not as great as might be expected. The magnet without the field homogenizers shows no indication of larger field inhomogeneities that can be ascribed to path-length differences.
A B-constant design for the pole pieces avoids field inhomogeneities due to the sources which are observed in the pole pieces with the sharp-cutoff profile.
