Due to the arrangement of the shield coil
3, the Z-direction electromagnet force exerted on the shield coil
3 becomes approximately zero. The R-direction electromagnet force is also exerted on the shield coil
3; however, because exerted outward in the R direction, this electromagnet force is not exerted on the bobbins and the supporting members per se. Accordingly, the shield bobbin supporting member is not required to support the shield bobbin for such a large electromagnetic force as is exerted on the shield bobbin of the conventional superconductive magnet; the shield bobbin supporting member may just support the shield bobbin for its own weight. In Embodiment 1, the shield bobbin
31 is supported by the shield bobbin supporting member
33 that is extended perpendicularly from the main bobbin
21. The shield bobbin supporting member
33 is a disc having a thickness of, for example, 10 mm, and is made of a non-magnetic material such as stainless steel. At the middle of the shield bobbin supporting member
33, there is provided an opening through which the main bobbin
21 passes; the shield bobbin supporting member
33 is ring- and disc-shaped as a whole. The shield bobbin supporting member
33, the main bobbin
21, and the shield bobbin
31 are coupled with one another through welding. The shield bobbin supporting member
33 is welded at a Z-direction position, in the main bobbin
21, in which no main coil
2 exists. As described above, the helium tank flange
41, the shield bobbin
31, and the shield bobbin supporting member
33 are coupled through welding; however, there are demonstrated the same operation and effect in the case where they are coupled through another coupling means such as bolt screwing.