Open C-shaped permanent magnets for NMR imaging

Previously developed design methodology provides a systematic analysis of magnetic structures composed of uniformly magnetized prisms that generate uniform fields. The approach is based on the property of cancellation of field singularities at the interfaces between the media. Applications of this design methodology thus far have been restricted to magnetic structures with concave cavity boundaries. However, convex cavity boundaries may be necessary for C-shaped magnetic structures involved in medical NMR imaging that feature a side opening in addition to openings at both ends. This paper introduces transition structures placed in the region of the magnet opening and analyzes their field properties. The results indicate a remarkable benefit of the transition elements in terms of field uniformity and the size of the imaging region.