Stability of Standard Platinum Cobalt Resistance Thermometers under Hundred Low-temperature Cycling

Abstract: The standard platinum cobalt resistance thermometer is an important temperature measuring device in the 0.65K-24.556 1K (neon three-phase point) temperature range, especially the highly stable standard platinum cobalt resistance thermometer has the potential to serve as a data carrier for temperature calibration and international temperature comparison. In order to screen out highly stable standard platinum cobalt resistance thermometers, this article establishes a low-temperature assessment device for thermometers using a refrigerator as the cold source based on previous research. The stability of 5K temperature control reaches 13 μ K. 24.556 1K temperature control stability reaches 27 μ K. Better than the publicly reported temperature control stability results of similar assessment devices currently available; Based on this, a hundred low temperature cycles of standard platinum cobalt resistance thermometers were conducted in the 5K-24.556 1K temperature range, and five highly stable standard platinum cobalt resistance thermometers were obtained. Among them, four 50 Ω standard platinum cobalt resistance thermometers had better stability than others 0.2mK@24.556 1K, 1 100 Ω standard platinum cobalt resistance thermometer has better stability than 0.5mK@24.556 1K is the best international result for low temperature stability of current standard platinum cobalt resistance thermometers. In the future, the high stability standard platinum cobalt resistance thermometer selected in this article will be used for low-temperature temperature calibration and international low-temperature temperature equivalence related applications and research.