| 摘要 |
PURPOSE:To obtain uniform, stable and high-accuracy magnetic field by providing annular projections for each of opposite planes of a pole piece. CONSTITUTION:Each of opposite planes of a pole pieces 2 is provided with annular projections 5. For example, a magnetic circuit used for an NMR-CT device is constituted as follows. The pole pieces 2 are fixed to one end of each of a pair of Fe-B-R group permanent magnets 1 and these face each other. Other ends are connected by a joint iron 3. In an air gap 4 between the pole pieces 2, a strong magnetic field of 1-10kG is generated and a part of a human body or the whole body is inserted in that air gap for making a diagnosis. Then, a pair of pole pieces 2 have outer diameters of D1, annular projections 5 having inner diameters of D2 and height of H are arranged on circumferential edges of the opposite planes and these projections face in the air gap 4. If the inner diameter planes of these annular projections are inclined planes, a good and uniform magnetic field can be obtained stably. |
