| 摘要 |
PURPOSE:To provide a superconducting magnet for nuclear magnetic resonance analysis purposes with a magnetic shield having a structure which substantially prevents the generation of a secondary axially symmetric magnetic field which is the major component of an irregular magnetic field. CONSTITUTION:A superconducting magnet is provided with a cylindrical cal superconducting coil 1, a cylindrical magnetic material 2, and a magnetic shield which is composed of a pair of plane closures of a magnetic material 3a and 3b which close both ends of the cylindrical magnetic material 2. The center axis of the cylindrical magnetic material 2 is in alignment with the center axis of the superconducting coil l, and the cylindrical material 2 and a pair of the closures of a magnetic material 3a and 3b are arranged so that a pair of the closures of a magnetic material 3a and 3b can be evenly spaced apart from each other relative to the center of the superconducting coil 1. The sizes of the cylindrical magnetic material 2 and a pair of the closure of a magnetic material 3a and 3b are determined in such a way that the ratio of R to H is in the range of 0.8 to 1.0, where R is the internal diameter of the cylindrical magnetic material 2, and 2H is a distance between the internal surfaces of a pair of the closures of a magnetic material 3a and 3b. |
