| 摘要 |
PURPOSE:To reduce intruded heat due to radiation and conduction and loss due to eddy current generated within a refrigerant container by a gradient coil by composing a part which exists between the gradient coil and a superconductive coil of two or more shielding materials consisting of materials with an improved electrical conductivity mutually coupled thermally. CONSTITUTION:A part of a thermal shield 2 which is greatly affected by a gradient coil 4, namely the part between a superconductive coil 5 and the gradient coil 4, is composed of two or more materials with improved electrical conductivity through a cylindrical electrical isolation layer. Thus, a fluctuating magnetic filed generated by the gradient coil 4 at a shielding part constituted in multiples, passing through the thermal shield 2 and reaching a refrigerant container 3, is reduced, thereby reducing loss of eddy current in the refrigerant container 3. |
