| 摘要 |
PURPOSE:To obtain uniform, stable and high-accuracy magnetic field by forming each of opposite planes of pole pieces into concave curve planes. CONSTITUTION:Each of oppostie planes of pole pieces are formed into concave curve planes. For example, a magnetic circuit used for an NMR-CT device is constituted as follows. Ploe pieces 2 are fixed to one end of each of a pair of Fe-B-R group permanent magnet 1 and these face each other. Other ends are connected by a yoke 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 D and the whole opposite planes compose concave planes 5. In other words, the pole piece has a shape like a concave lens one side of which is flat and a pair of concave curve planes 5 face each other in the air gap 4. The concave curve plane 5 is formed with a curvature radius R, for example. |
