| 摘要 |
PROBLEM TO BE SOLVED: To obtain a superconductive electromagnet small in size and high in reliability, and an MRI device employing it. SOLUTION: The MRI device is arranged between a cylindrical helium tank 2 with an annular superconductive coil 1 for generating magnetic field and reserving liquid helium 3 for cooling the superconductive coil 1, and a vacuum tank 5 arranged so as to surround the helium tank 2; and is constituted so as to reduce the invasion of radiation heat into the helium tank 2 by heat shields 6, 7 cooled by a refrigerating machine 8, while pouring additionally the liquid helium 3 from a service port 11 into the helium tank 2. Further, the central position of the superconductive coil 1 is arranged at a position deviated downward from the central position of an outside circle forming the section of the helium tank 2, whereby the small-sized superconductive electromagnet is obtained in spite that the volume of the helium tank 2 above the lower limit level 10 of the liquid helium 3 is same compared with that of a conventional helium tank. COPYRIGHT: (C)2005,JPO&NCIPI |
