| 摘要 |
PROBLEM TO BE SOLVED: To eliminate discharge failures between a bolt and a current feeder line by employing a nonmetallic bolt for securing an electrode bottom plate and a current feeder line to a cooling stage. SOLUTION: A nonmetallic bolt 27, having high electric insulation performance and mechanical strength, is employed for securing a current feeder line guiding a superconducting wire 26, to be connected with a superconducting coil 25 and the electrode bottom plate 15 of a superconducting current lead to the cooling stage 6b of a refrigerator 4 through an insulation board 16. Since the nonmetallic material of the bolt 27 is used at a part being cooled from a normal temperature to a cryogenic temperature, drastic thermal shrinkage takes place. Consequently, it must withstand against thermal contraction, while exhibiting electric insulating function. Synthetic resin material such as polyether etherketone, Teflon (R), nylon or ERP (fiber reinforced plastic), can be employed as a material satisfying these conditions. According to the arrangement, the current feeder line and the electrode bottom plate can be cooled, without causing dielectric breakdown between the electrode bottom plate or the current feeder line and the cooling stage. |
