Key Comparison: Realisations of the ITS-90 scale over the range from the Ag fixed-point to 2600 °C

Project Description

In the recent European projects “Implementing the new kelvin - InK” and “Realising the new kelvin – Real-K”, a thermodynamic temperature has definitely been assigned to the freezing plateau of the Cu fixed point (1084.65 °C) and to the inflection points of the melting plateaus of the following high temperature fixed-points: Fe-C (1153.77 °C), Co-C (1324.24 °C), Pd-C (1491.90 °C), Pt-C (1738.28 °C), Ru-C (1953.84 °C), Re-C (2474.69 °C) and WC-C (2747.70 °C).

This research provides the opportunity to use high temperature fixed points (HTFPs) to perform a temperature scale directly linked to the thermodynamic temperature. The use of multi fixed-points is an alternative method to the ITS-90 allowing the calibration of radiation thermometers over a wide temperature range without the need to characterise its spectral responsivity or linearity.

This project aims to support cooperation between European NMIs. It is conducted as part of the Joint Research Project MultiFixRad 22RPT03/r02 “Improving the realisation of the kelvin by multiple fixed point radiation thermometry” and consist of a comparison of temperature scale realisations from the Ag fixed-point to 2600 °C. The reference instrument is a near-infrared radiation thermometer whose stability will be monitored throughout the comparison with a transportable copper fixed-point.

The traceability to the CCT-K10 will be established by the intermediate of LNE-LCM/Cnam.

This project is the final step of the Joint Research Project “Improving the realisation of the kelvin by multiple fixed point radiation thermometry” MultiFixRad n° 22RPT03/r02.