New Cryostat for Long Stem Thermometer Calibration in Argon Triple Point
The triple point of Argon (83,8058 K) is the lowest point on ITS-90 temperature scale to be used for long stem standard resistance thermometers calibration. Its realization, in most European metrology institutes, is based on devices designed by BNM-INM (now LNE-INM). This classical system works with an Ar cell totally immersed in a nitrogen bath. The N2 temperature around the cell is regulated by adjusting its pressure through a mechanical control valve.A preliminary study identified the main points to be improved in this Ar fixed point system: the influence of the atmospheric pressure changes on the temperature control of the N2 bath and the change in the N2 free-liquid level which causes a temperature gradient modification inside the bath and changes in the immersion depth of the thermometer. In order to solve those problems and to both ensure longer calibration plateaus and lower uncertainties, a new cryostat was manufactured. The new design ensures that the liquid free-level of N2 is above the thermometer head during the whole experiment. In order to overcome the atmospheric pressure dependence of the former system, the regulation now involves an electronic regulator controlled by a thermometer immersed in the N2 bath. This will maintain a constant temperature in the liquid bath when N2 free liquid-level will change. The paper aims to present the principles of this new Ar cryostat design and its first tests.
Metrology Contact thermometry Fized points Argon triple point ITS-90
Miruna Dobre Yves Hermier
SMD, 1000 Brussels, Belgium LNE-INM/CNAM, 93210 La Plaine St Denis, France
国际会议
2008年国际温度与热物性测量会议(TEMP BEIJING 2008)
北京
英文
216-219
2008-10-20（万方平台首次上网日期，不代表论文的发表时间）