Effect of minor loop on magnetic characteristics of permanent magnet type of MRI

A modeling technique of the minor loop using typical hysteresis loops is shown. The effect of the minor loop and eddy current in the pole piece of a permanent magnet type of MRI on the residual flux density of the probe coil is examined. It is illustrated that the change /spl Delta/B of residual flux density occurs due to the minor loop of the pole piece. It is also pointed out that the choice of time interval /spl Delta/t is important in a nonlinear analysis considering the minor loop.