| 摘要 |
PURPOSE:To eliminate the attenuation of an induced current by a method wherein a thermal shielding cylinder is composed of a superconducting material which is brought into a superconducting state at the liquid nitrogen temperature or higher. CONSTITUTION:A superconducting material, which turns into a superconducting state at or higher than the temperature of liquid nitrogen and connected to a thermal shielding end plate 8 maintained at the temperature of liquid nitrogen, such as a thermal shielding cylinder 21 made of ceramic superconducting material, for example, and a heater 22, which is wound on a thermal shielding cylinder for the purpose of transposing the ceramic superconducting thermal shielding 21 into normal conductivity, are formed. Said thermal shielding cylinder 21, on which an induced current is allowed to flow, is turned into a superconducting state by cooling down the temperature of liquid nitrogen, and as a result, its resistance becomes zero, and the attenuation of the induced current, caused by the resistance of the thermal shielding cylinder 21, is eliminated. Accordingly, the output magnetic field of the title magnet device can be maintained constant. |
