| 摘要 |
PURPOSE:To take an exact measurement at wide-range temperatures by providing an annular part at plural reference positions of a superconductor, detecting abrupt variation in the resistance of the superconductor when a liquid helium level passes through an annular part, and calibrating the resistance value of the superconductor according to the reference position. CONSTITUTION:A sensor 10 has the superconductor 11, which is provided with annular parts (r) made of conductors 11 bent at right angles to the lengthwise direction at plural reference positions which are set lengthwise as constant intervals. The sensor 10 is installed in a Dewar flask and liquid helium 12 is injected from above. A current lead wire 13 and a voltage lead wire 14 are connected to the upper terminal and lower terminal of each conductor 11; the wire 13 is connected to a constant current source 16 and the wire 14 is connected to a CPU19 through a differential amplifier 17 and an A/D converter 18. The CPU 19 measures abd stores a voltage VIN when the helium rises in level and reaches the annular parts r0, r1,... and calibrates the resistance value of the conductor 11 according to the reference position, thereby taking an accurate measurement at wide-range temperatures. |
