核聚变装置通常在超低温环境下运行,对温度的精确测量有着严苛的要求.超低温环境下的温度精确测量与标定直接影响着核聚变、高能物理、航空航天等涉及超低温环境的研究领域的发展.根据聚变堆主机系统综合研究设施CRAFT的测试条件,设计了液氦温度计标定平台,可开展1.8～300 K温区内的温度标定与实验研究.该平台通过吉福德-麦克马洪循环制冷机(GM制冷机)以及毛细管节流制冷,实现样品腔降温至1.8 K;通过调节加热器功率控制样品腔温度,可实现1.8～20 K温区内±5mK波动、20～300 K温区内±15 mK波动的温度环境条件.使用低温测量控制设备对标定区域进行不同温度点位的控温和数据采集,最终得到标定精度结果为:1.8～4.2 K 时为±9.54 mK;4.2～20 K 时为±22.44 mK;20～300 K 时为±346.78 mK.
Design and Test Analysis of Thermometer Calibration Platform for 1.8 K to 300 K
The precise measurement of temperature is crucial for nuclear fusion devices operating in ultra-low tempera-ture magnetic field environments.The accurate temperature measurement and calibration in ultra-low temperature environ-ment has a direct impact on the development of nuclear fusion,high energy physics,aerospace and other research fields in-volving ultra-low temperature environment.Relying on the comprehensive research facility CRAFT for fusion reactor host systems,a liquid helium temperature calibration platform has been designed to carry out temperature calibration and experi-mental research in the temperature range of 1.8 K to 300 K.The platform uses the Gifford-McMahon Cycle Chiller(GM Chiller)and capillary throttling refrigeration to cool the sample chamber to 1.8 K.By controlling the temperature of the sam-ple chamber by adjusting the heater power,the temperature environment of±5 mK fluctuation in the temperature zone of 1.8 K to 20 K and±15 mK fluctuation in the temperature zone of 20 K to 300 K can be achieved.Low-temperature measure-ment and control equipment are used for temperature control and data acquisition at different temperature points in the cali-bration area,resulting in a calibration accuracy of±4.39 mK at 1.8 K to 4.2 K,±6.08 mK at 4.2 K to 20 K,and±75.62 mK at 20 K to 300 K.
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