Shape optimization of iron shield for superconducting solenoid magnets

The superconducting solenoid magnet for high energy physics or the MRI systems use the iron shield to enhance the central field or to shield the strong leakage magnetic field. But the design technique of the iron shape has not been established, since the iron has nonlinear permeabillty. In the present paper, a optimizing procedure of the iron shield shape is proposed. Our procedure is based on the hybrid finite element-boundary element method(HFB method). The HFB method is suited to analysis of problem which present nonlinear behavior and extend to infinity. The HFB method may facilitate to optimize the shape of the nolinear iron shield.