State Primary Standard of Temperature Unit in the Range 0–3200°C GET 34-2020: Practical Implementation of the New Definition of Kelvin

We consider the necessity and means of modernizing the State primary standard GET 34-2007 of the unit of temperature in the range of 0–3000°С. The problem of transition to a new definition of kelvin is highlighted. It is shown that the new definition of kelvin does not directly affect the status of the current international temperature scales ITS-90 and PLTS-2000, however, it provides significant advantages for measuring thermodynamic temperatures below 20 K and above about 1300 K. In this regard, the main direction of modernization of GET 34- 2007 in the range of 273.15–1235 K is associated with the improvement of methods and means of implementing the ITS-90. As part of the work on the modernization of the standard in the range above 1235 K, a complex of equipment was created that allows reproducing the kelvin in accordance with its new definition by two methods: absolute primary radiometric thermometry and relative primary radiometric thermometry. The methods are recommended by the Thermometry Advisory Committee of the International Bureau of Weights and Measures. The basic principles of the implementation of these methods, as well as the composition and metrological characteristics of the GET 34-2020 approved in 2020, are outlined. The results of key comparisons of GET 34-2020 in the range of 273.16–692.477 K are presented, as well as the results of temperature measurements of a number of high-temperature reference points and their comparison with the published results of similar measurements by leading national metrological institutes.