Magnetic Field Analysis of Permanent Magnet Type MRI

--Effect of Minor Loop in Yoke--

Abstract

The permanent magnet type MRI for whole body provides a viable alternative to resistive and superconducting MRI. As the permanent magnet assembly contains pole pieces and yokes which are made of steel, the minor loop of B and H of steel due to the pulse excitation and the eddy current induced in the steel affect the magnetic characteristics of permanent magnet assembly. In this paper, the effects of minor loop and eddy current in yoke on the behavior of flux density are investigated. The detailed behavior of B and H in minor loops is illustrated. It is shown that the minor loop and eddy current in yoke affect the residual flux density considerably.