Open AccessMeasurement of thermodynamic temperature between 5 K and 24.5 K with single-pressure refractive-index gas thermometry
Author(s) -
Bo Gao,
Haiyang Zhang,
Dongxu Han,
Changzhao Pan,
Hui Chen,
Yaonan Song,
Wenjing Liu,
Jianxing Hu,
Kong Xiangjie,
F. Sparasci,
Mark Plimmer,
Ercang Luo,
Laurent Pitre
Publication year - 2020
Publication title -
metrologia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.637
H-Index - 79
eISSN - 1681-7575
pISSN - 0026-1394
DOI - 10.1088/1681-7575/ab84ca
Subject(s) - thermodynamic temperature , scale of temperature , temperature measurement , materials science , atmospheric temperature range , thermodynamics , resistance thermometer , refractive index , work (physics) , cryostat , hydrostatic equilibrium , physics , condensed matter physics , superconductivity , quantum mechanics , optoelectronics
We describe measurements of thermodynamic temperature in the range 5 K to 24.5561 K (the triple point of neon) using single-pressure refractive-index gas thermometry (SPRIGT) with 4 He. In the wake of the May 2019 re-definition of the kelvin and its associated mise en pratique , the main purpose of the work is to provide values of T – T 90 , the discrepancy between thermodynamic temperature and that of the International Temperature Scale of 1990 (ITS-90). The link to ITS-90 is made via calibrated rhodium-iron resistance thermometers. Innovations required to reach the level of accuracy required for meaningful measurements (uncertainty in T – T 90 less than the expected deviation) include the suppression of temperature oscillations in a cryogen-free cryostat, a pressure stabilization scheme based on a non-rotating piston balance, modelling of the hydrostatic head correction and refinements of the measurement of microwave resonances in a quasi-spherical copper resonator. The accuracy of measurements varies from 0.05 mK to 0.17 mK and is competitive with that of all previous ones in this temperature range using other techniques. The improvement stems partly from the new techniques used for the new definition of the kelvin as well as ab initio calculations of the thermophysical properties ofgaseous 4 He. In addition to confirming the validity of SPRIGT as an accurate, easier-to-implement alternative to other low-temperature primary thermometry techniques (e.g. acoustic gas thermometry) yet with scope for improvement, the results should provide important input data for any future revision of ITS-90.