Realisation of the ITS-90 and thermodynamic temperature measurements above 960 °C using a monochromator-based radiance comparator

Metrologia ◽  
2021 ◽  
Author(s):  
Frederic Bourson ◽  
Stéphan Briaudeau ◽  
Mohamed Sadli ◽  
Bernard Rougie ◽  
Olga Kozlova
Keyword(s):  
Temperature Scale ◽  
Narrow Band ◽  
Thermodynamic Temperature ◽  
Interference Filter ◽  
Temperature Measurements ◽  
Scattering Function ◽  
Sources Of Uncertainty ◽  
International Temperature Scale ◽  
Complete Study ◽  
Silver Point

Abstract At LNE-Cnam, the International Temperature Scale of 1990 (ITS-90) and thermodynamic temperature measurements above the silver point, are carried out with a radiance comparator. This instrument is, more generally, devoted to any radiance comparison in temperature range from the ambient to 3000 °C. The instrument developed in the early 1990s at LNE-Cnam has the advantage of being completely adjustable. Compared to compact radiation thermometers based on lenses and a narrow-band interference filter, the radiance comparator is only made of gold coated mirrors and a Czerny-Turner monochromator to select the spectral bandwidth. The instrument offers the possibility to tune the geometric extent and the slit scattering function. In return, the radiance comparator is a complex instrument that requires a complete and a regular characterisation at the highest level of accuracy. In the first part, this paper describes the instrument and its operating principle. In a second part, a complete study of the wavelength calibration, the slit scattering function, size of source effect, out-of-band transmittance, linearity and other main sources of uncertainty are presented and discussed. Their associated uncertainties are estimated separately and are grouped together to give an example of propagation of uncertainties when performing the ITS-90.

The methods of realization of ITS-90 fixed points: the necessity for improvement

2021 ◽  
pp. 42-47
Author(s):  
Alina G. Ivanova ◽  
Sergei F. Gerasimov ◽  
Anatolii I. Pokhodun ◽  
Viktor M. Fuksov
Keyword(s):  
Fixed Points ◽  
Temperature Scale ◽  
International Comparisons ◽  
Interface Structure ◽  
National Standards ◽  
Measured Temperature ◽  
Sources Of Uncertainty ◽  
International Temperature Scale ◽  
Outer Interface ◽  
Liquid And Solid Phases

The consistency of the results of international comparisons and the equivalence of national standards, improvement of methods for the realization of the International Temperature Scale ITS-90 main fixed points of metals freezing are considered. Two sources of uncertainty of the temperature value during realization of metals freezing fixed points have been determined. Experiments on the initiation of the inner interface between the liquid and solid phases of the metal have been carried out, the effect of the initiation conditions on the interface structure and measured temperature value in aluminum and indium fixed points cells has been investigated. The question of the correctness of the impurities influence estimates according to the laws for the only outer interface moving from the crucible walls to its center is considered. Analysis of the freezing curves obtained under different initiation conditions allowed determining the criterion for the presence of a continuous inner interface and the conditions for the formation of a single outer interface during slow crystallization of the metal without the formation of an inner interface. The obtained criteria will allow metrological institutes to choose the correct conditions for the initiation of the inner interface when using different designs of cells and heaters.

scholarly journals Overview of measurements capabilities in radiation thermometry at CEM (Spain)

2019 ◽  
Author(s):  
M. J. Martin ◽  
J. M. Mantilla ◽  
D. del Campo
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Temperature Scale ◽  
Radiation Thermometry ◽  
Thermodynamic Temperature ◽  
National Standards ◽  
Primary Radiation ◽  
International Temperature Scale ◽  
Definition Of The Kelvin ◽  
Definition Of

CEM (Spanish National Institute of Metrology) is responsible for the maintenance and dissemination of the temperature national standards. Nowadays, the CEM Radiation Thermometry Laboratory disseminates and maintains the International Temperature Scale of 1990 (ITS-90) from the Ag fixed point (961.78 °C) to 2800 °C, using Ag or Cu fixed points as reference and standard radiation thermometers (RTs) working at a wavelength of 650 nm. CEM is also able to provide traceability to the new definition of the kelvin and to perform measurements of thermodynamic temperature from 400°C to 2800°C with different RTs (wavelengths of 650 nm, 900 nm and 1550 nm) using absolute and relative primary radiation thermometry. In addition the Radiation Thermometry laboratory performs calibration of RTs working in the usual infrared ranges (1 μm and 10 μm) from – 40°C to 1600°C.

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

2016 ◽  
Vol 374 (2064) ◽  
pp. 20150048 ◽  
Author(s):  
R. Underwood ◽  
M. de Podesta ◽  
G. Sutton ◽  
L. Stanger ◽  
R. Rusby ◽  
...  
Keyword(s):  
Speed Of Sound ◽  
Temperature Scale ◽  
Opposite Sign ◽  
Thermodynamic Temperature ◽  
Acoustic Resonator ◽  
International Temperature Scale ◽  
Acoustic Thermometry ◽  
International Temperature ◽  
The Difference

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.

Realization of new definition of kelvin on National primary state standard of temperature in the temperature range from 0.3 K to 273.16 K GET 35-2021

2021 ◽  
pp. 8-15
Author(s):  
Vladimir G. Kytin ◽  
Mamikon Yu. Ghavalyan ◽  
Aleksey A. Petukhov ◽  
Boris G. Potapov ◽  
Yakov E. Razhba ◽  
...  
Keyword(s):  
State Standard ◽  
Temperature Scale ◽  
Thermodynamic Temperature ◽  
Primary State ◽  
Primary State Standard ◽  
Temperature Range ◽  
International Temperature Scale ◽  
Definition Of ◽  
Unit Of Temperature ◽  
Gas Thermometry

Description and metrological characteristics are presented of upgraded in 2021 equipment of National primary state standard of temperature on the temperature range from 0.3 K to 273.16 K GET 35-2021. GET 35-2021 allow to to the reproduce and disseminate the unit of temperature according to its definition accepted on 26th CGPM in 2018. Three installations of acoustic gas thermometry developed in 2012–2019 have been introduced in the National primary state standard covering ranges 79–273.16 K, 4.2–80 K, 268.16–273.16 K. The equipment for reproduction of fixed points of of International Temperature scale ITS-90 has been upgraded for uncertainty reduction. Uncertainty of reproduction of thermodynamic temperature and temperature according to ITS-90 have been calculated on the basis of investigations of upgraded equipment.

scholarly journals Thermodynamic temperature by primary radiometry

2016 ◽  
Vol 374 (2064) ◽  
pp. 20150041 ◽  
Author(s):  
Klaus Anhalt ◽  
Graham Machin
Keyword(s):  
Temperature Scale ◽  
Radiation Thermometry ◽  
Thermodynamic Temperature ◽  
Freezing Temperature ◽  
Radiation Detectors ◽  
Experimental Procedure ◽  
Different Types ◽  
Silver Point ◽  
Planck’S Law ◽  
Low Uncertainty

Above the freezing temperature of silver (1234.93 K), the International Temperature Scale of 1990 (ITS-90) gives a temperature, T 90 , in terms of a defining fixed-point blackbody and Planck's law of thermal radiation in ratio form. Alternatively, by using Planck's law directly, thermodynamic temperature can be determined by applying radiation detectors calibrated in absolute terms for their spectral responsivity. With the advent of high-quality semiconductor photodiodes and the development of high-accuracy cryogenic radiometers during the last two decades radiometric detector standards with very small uncertainties in the range of 0.01–0.02% have been developed for direct, absolute radiation thermometry with uncertainties comparable to those for the realization of the ITS-90. This article gives an overview of a number of design variants of different types of radiometer used for primary radiometry and describes their calibration. Furthermore, details and requirements regarding the experimental procedure for obtaining low uncertainty thermodynamic temperatures with these radiometers are presented, noting that such radiometers can also be used at temperatures well below the silver point. Finally, typical results obtained by these methods are reviewed.

Photo-electric Hβ and uvby photometry

1966 ◽  
Vol 24 ◽  
pp. 170-180
Author(s):  
D. L. Crawford
Keyword(s):  
Narrow Band ◽  
Line Strength ◽  
Interference Filter ◽  
B Stars ◽  
Relative Line ◽  
The Mean ◽  
F Stars ◽  
Two Parameters ◽  
Filter Photometry ◽  
The Continuum

Early in the 1950's Strömgren (1, 2, 3, 4, 5) introduced medium to narrow-band interference filter photometry at the McDonald Observatory. He used six interference filters to obtain two parameters of astrophysical interest. These parameters he calledlandc, for line and continuum hydrogen absorption. The first measured empirically the absorption line strength of Hβby means of a filter of half width 35Å centered on Hβand compared to the mean of two filters situated in the continuum near Hβ. The second index measured empirically the Balmer discontinuity by means of a filter situated below the Balmer discontinuity and two above it. He showed that these two indices could accurately predict the spectral type and luminosity of both B stars and A and F stars. He later derived (6) an indexmfrom the same filters. This index was a measure of the relative line blanketing near 4100Å compared to two filters above 4500Å. These three indices confirmed earlier work by many people, including Lindblad and Becker. References to this earlier work and to the systems discussed today can be found in Strömgren's article inBasic Astronomical Data(7).

ACCURACY OF OPTICAL PYROMETRY IN THE RANGE 800 °C TO 4000 °C

1958 ◽  
Vol 36 (10) ◽  
pp. 1397-1408 ◽  
Author(s):  
D. R. Lovejoy
Keyword(s):  
Standard Deviation ◽  
Temperature Scale ◽  
Primary Standard ◽  
Secondary Standard ◽  
Optical Pyrometer ◽  
Optical Pyrometry ◽  
International Temperature Scale ◽  
International Temperature ◽  
Carbon Arc ◽  
Temperature Standard

A pair of secondary standard tungsten strip lamps have had a luminance temperature – current calibration, in the range 800 °C to 2200 °C, at a number of national laboratories. An analysis of the calibration results confirms estimates of the accuracy of optical pyrometry in the range 800 °C to 2200 °C and supports the extension of these estimates to 4000 °C. The standard deviation uncertainty of optical pyrometry is shown to be about 1 °C at 800 °C rising to 2 °C at 2200 °C and 10 °C at 4000 °C, being about double this for the calibration of commercial pyrometers unless certain described precautions are taken.The reliability of the secondary standard lamps, when used under well-defined conditions, is confirmed and it is shown that they have a standard deviation calibration uncertainty of about 1 °C for the vacuum-type lamps in the range 800 °C to 1500 °C and 2 °C for the gas-filled lamps in the range 1500 °C to 2200 °C. Most of this uncertainty is due to primary standard optical pyrometer calibration errors. Attention is drawn to the fact that a carbon arc fulfills the requirements of a secondary luminance temperature standard at about 3514 °C.Recent determinations of the gold point and the second radiation constant indicate that the 1948 International Temperature Scale is lower than the thermodynamic scale by an amount varying from 0.8 °C at 800 °C to 12 °C at 4000 °C. This is already greater than the calibration errors of optical pyrometry and, in view of the still greater accuracies presaged by photomultipliers, a revision of the International Temperature Scale is suggested.

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

2018 ◽  
Vol 11 (8) ◽  
pp. 4757-4762 ◽  
Author(s):  
Friedhelm Olschewski ◽  
Christian Monte ◽  
Albert Adibekyan ◽  
Max Reiniger ◽  
Berndt Gutschwager ◽  
...  
Keyword(s):  
Temperature Scale ◽  
Environmental Research ◽  
Large Area ◽  
Atmospheric Measurements ◽  
Calibration Source ◽  
Aperture Diameter ◽  
International Temperature Scale ◽  
International Temperature ◽  
Long Duration ◽  
Better Than

Abstract. 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.

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