Compensation of non-uniform magnetic properties of components of a yokeless permanent magnet

The authors present a method for compensating for nonuniformity of magnetization in a yokeless permanent magnet designed for clinical applications of nuclear magnetic resonance (NMR). The field generated by the magnet is confined within the magnetic material without the use of an external yoke. The method involves two steps: compensation in the individual magnet components and shimming of the assembled magnet. The authors concentrate on the first step, and, in particular, the compensation of the lowest harmonics of the field