Primary state standard of the temperature in the range from 0 to 3200 °С, GET 34-2020: practical implementation of the new definition of kelvin

The article considers the necessity of ways of modernization the Primary standard of the temperature GET 34-2007. Special attention is paid to the transition to a new definition of kelvin. Taking into account that the new definition of kelvin does not directly affect the status of the current international temperature scales ITS-90 and PLTS-2000, but there are significant advantages for measuring thermodynamic temperatures below 20 K and above ~1300 K, the main focus of the modernization of the GET 34-2007 in the range from 273.15 K to 1235 K was focused on improving the methods and means of implementing the International Temperature Scale ITS-90. As part of the modernization of the Primary standard in the range above 1235 K, a set of equipment has been created that allows the reproduction of kelvin in accordance with its new definition by two methods recommended by the Consultative Committee: the method of absolute primary radiometric thermometry and the method of relative primary radiometric thermometry. The basic principles of the implementation of these methods, composition and metrological characteristics of the Primary standard are described. The results of key comparisons of the developed standard in the range from 273.16 K to 692.477 K and the results of temperature measurements of a number of high-temperature fixed points and a comparison of the results with the published results of leading national metrological institutes are presented.

A large-area blackbody for in-flight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research

The deployment of the imaging Fourier Transform Spectrometer GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on board a long-duration balloon for stratospheric research requires a blackbody for in-flight calibration in order to provide traceability to the International Temperature Scale (ITS-90) to ensure comparability with the results of other experiments and over time. GLORIA, which has been deployed onboard various research aircraft such as the Russian M55 Geophysica or the German HALO in the past, shall also be used for detailed atmospheric measurements in the stratosphere up to 40 km altitude. The instrument uses a two-dimensional detector array and an imaging optics with a large aperture diameter of 36 mm and an opening angle of 4.07∘ × 4.07∘ for infrared limb observations. To overfill the field of view (FOV) of the instrument, a large-area blackbody radiation sources (125 mm × 125 mm) is required for in-flight calibration. In order to meet the requirements regarding the scientific goals of the GLORIA missions, the radiance temperature of the blackbody calibration source has to be determined to better than 100 mK and the spatial temperature uniformity shall be better than 150 mK. As electrical resources on board a stratospheric balloon are very limited, the latent heat of the phase change of a eutectic material is utilized for temperature stabilization of the calibration source, such that the blackbody has a constant temperature of about −32 ∘C corresponding to a typical temperature observed in the stratosphere. The Institute for Atmospheric and Environmental Research at the University of Wuppertal designed and manufactured a prototype of the large-area blackbody for in-flight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research. This newly developed calibration source was tested under lab conditions as well as in a climatic and environmental test chamber in order to verify its performance especially under flight conditions. At the PTB (Physikalisch-Technische Bundesanstalt), the German national metrology institute, the spatial radiance distribution of the blackbody was determined and traceability to the International Temperature Scale (ITS-90) has been assured. In this paper the design and performance of the balloon-borne blackbody (BBB) is presented.

A large-area blackbody for inflight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research

The deployment of the imaging Fourier Transform Spectrometer GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on board a long-duration balloon for stratospheric research requires a blackbody for inflight calibration in order to provide traceability to the International Temperature Scale (ITS-90) to ensure comparability with the results of other experiments and over time. GLORIA, which has been deployed onboard various research aircraft such as the Russian M55 Geophysica or the German HALO in the past, shall also be used for detailed atmospheric measurements in the stratosphere up to 40 km altitude. The instrument uses a two-dimensional detector array and an imaging optics with a large aperture diameter of 36 mm and an opening angle of 4.07° × 4.07° for infrared limb observations. To overfill the field-of-view (FOV) of the instrument, a large-area blackbody radiation sources (125 mm × 125 mm) is required for inflight calibration. In order to meet the requirements regarding the scientific goals of the GLORIA missions, the radiance temperature of the blackbody calibration source has to be determined to better than 100 mK and the spatial uniformity shall be better than 100 mK. Since electrical resources onboard a stratospheric balloon are very limited, the latent heat of the phase change of a eutectic material is utilized for temperature stabilization of the calibration source, such that the blackbody has a constant temperature of about −32 °C corresponding to a typical temperature observed in the stratosphere. The Institute for Atmospheric and Environmental Research at the University ofWuppertal designed and manufactured a prototype of the large-area blackbody for inflight calibration of an infrared interferometer deployed onboard a long-duration balloon for stratospheric research. This newly developed calibration source was tested under lab conditions as well as in a climatic and environmental test chamber in order to verify its performance especially under flight conditions. At PTB (Physikalisch-Technische Bundesanstalt), the German national metrology institute the spectral and spatial radiance distribution of the blackbody was determined and traceability to the International Temperature Scale (ITS-90) has been assured. In this paper the design and performance of the Balloon-borne BlackBody (BBB) is presented.

Estimates of the difference between thermodynamic temperature and the International Temperature Scale of 1990 in the range 118 K to 303 K

Using exceptionally accurate measurements of the speed of sound in argon, we have made estimates of the difference between thermodynamic temperature, T , and the temperature estimated using the International Temperature Scale of 1990, T 90 , in the range 118 K to 303 K. Thermodynamic temperature was estimated using the technique of relative primary acoustic thermometry in the NPL-Cranfield combined microwave and acoustic resonator. Our values of ( T − T 90 ) agree well with most recent estimates, but because we have taken data at closely spaced temperature intervals, the data reveal previously unseen detail. Most strikingly, we see undulations in ( T − T 90 ) below 273.16 K, and the discontinuity in the slope of ( T − T 90 ) at 273.16 K appears to have the opposite sign to that previously reported.