Purpose - The purpose of this paper is to provide an approach to the optimal design of open type magnetic circuit of permanent magnet having uniform field.
Design/methodology/approach - The Biot-Savart's law and evolution strategy are used for the design of permanent magnet configuration. The optimization is carried out by changing the objective function, dimension of target region, and target flux density.
Findings - The obtained uniformity is affected by the selection of objective function, dimension of target region, and target flux density. About 50 ppm uniformity of 0.08 T in the imaging area is obtained by changing the dimensions, dimension of target region, and target flux of 3D magnets and the amplitudes of magnetization and the directions of magnetization vectors.
Originality/value - This paper describes a new approach for obtaining the optimal shape of open type magnetic circuit which may be used when magnetic resonance imaging is carried out.