| 摘要 |
PURPOSE:To enable the carrying into an existing hospital building and installation therein with ease with a compact shape, a less weight and a low magnetic field leakage while achieving a highly uniform magnetic field by a method wherein a disc-shaped end lid is made up of a magnetic disc with a center hole and a non-magnetic ring joined inside the center hole and the magnetic disc is joined to a cylindrical shell while the non-magnetic ring joined to a normal temperature bore cylinder to form a vacuum container as a whole. CONSTITUTION:A container comprising a cylindrical shell 3, a disc-shaped end lid 4 and a normal-temperature bore cylinder 91 acts as vacuum container of a magnet 2 as in the past. On the other hand, as regard to a magnetic shield, a portion comprising the cylindrical shell 3 and a magnetic disc 14 functions as yoke magnetic shield. Under a situation with a length of a superconductive coil 12 and a shape of a cylindrical shell 3 determined, a width of the non- magnetic ring is adjusted, that is, an open diameter of the magnetic disc 14 is adjusted to be optimized. This enables the lowering of a magnetic field leakage in a magnetic circuit comprising the superconductive coil 12, the cylindrical shell 3 and the magnetic disc 14 while the formation of a highly uniform magnetic field. |
