| 摘要 |
PURPOSE: To provide an extremely low temperature current leading wire in which direct cooling by helium vapor is unnecessary by a method wherein a leading wire composed of tapered ceramic superconductor reduces heat conduction from a first step heat exchanger station to a second step heat exchanger station. CONSTITUTION: In a low temperature end portion of sleeves of a very low temperature cooler within a vacuum housing 260, two straight ceramic leading wires 261 extend from 50 deg.K and 10 deg.K stations 263, 265 of sleeves of the very low temperature cooler, respectively. The leading wires are tapered, and a sectional area of the leading wire an a high temperature side is still more larger. The ceramic leading wire is thermally coupled to the 50 deg.K and 10 deg.K heat stations 263, 265, respectively. A high temperature portion of the leading wire between surroundings (300 deg.K) and the 50 deg.K heat station comprises a conductor of copper having optimized value for L/A so that heat transmitted to the 50 deg.K station at the time of an operation current is made minimum. |
