Fundamental investigation of 3D optimal design of open type magnetic circuit producing uniform field

Purpose - To provide an approach to design the optimal open type magnetic circuit of permanent magnet producing uniform field. Design/methodology/approach - The Biot-Savart's law and evolution strategy are used for the initial design of permanent magnet configuration. In order to improve the uniformity, the ON/OFF method, which is the topology optimization method, is used for deter-mining the shape of magnetic material which is set around the permanent magnet. Findings - The optimal topology of permanent magnet and shape of magnetic material around it, which can produce nearly uniform field of about 0.15T, is obtained. The obtained uniformity is 3,583 ppm. More work for improving the uniformity is necessary. Originality/value - A new approach for obtaining the optimal shape of open type magnetic circuit which may be used for magnetic resonance imaging is carried out.