| 摘要 |
PURPOSE:To reduce the cross-sectional area of an inclined magnetic field coil, to contrive accomplishment of lightweightedness, miniaturization and improvment in accuracy of magnetic field by a method wherein the inclined magnetic field coil provided at a normal temperature part is provided in a liquid nitrogen bath. CONSTITUTION:An inclined magnetic field coil 9 is provided in the liquid nitrogen bath 2 located inside a 30K shield 4 and a normaltemperature cylinder 8, namely, at an intermediate position between a superconductive coil and a high frequency coil, and the coil 9 is cooled to the temperature of liquid nitrogen, which is about 78K. Consequently, the electric resistance of the coil conductor is reduced to about 1/8 of the normal temperature of 300K. To be more precise, in the case wherein the same electric resistance is present, the area of conductor required is reduced to 1/8, and the weight is also reduced to 1/8. Also, as the coil 9 is cooled with liquid nitrogen, it is unnecessary to place a spacer and the like between coil layers, and the coil 9 can be made smaller in size. As a result, the entire device can be made small in size and light in weight, and the accuracy of magnetic field can also be improved. |
