3-D magnetic field analysis of permanent-magnet type of MRI taking account of minor loop

Authors have reported the behavior of residual magnetization in the permanent-magnet type of magnetic resonance imaging (MRI), but the analysis was limited to axi-symmetric finite-element method (FEM). In order to obtain a more accurate behavior, three-dimensional (3-D) magnetic field analysis taking account of the minor loop is indispensable. In this paper, the behavior of the minor loop and eddy current in a 3-D model, which was not clear until now, is examined. It is shown that the minor loop is considerably changed due to the eddy current