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Presentation to be given at ‘Sensor and Measurement Science International’, hybrid conference: face-to-face and virtual, 3 – 6 May 2021, Nuremburg, Germany
Reliable temperature measurement impacts almost every sphere of human endeavour such as body temperature measurement in healthcare, a very wide range of manufacturing from iron, steel, glass to paper, plastics, semiconductors and additive manufacturing, trustworthy weather forecasting in meteorology, base line measurements for tracking climate change, and in a vast range of scientific research endeavours from space and aerospace to quantum information processing.
The foundation of reliable temperature, and in fact all, measurement is the International system of Units (SI) which has seven base units. In addition to the kelvin, these are the metre, second, kilogram, mole, ampere and candela. Together these form a globally accepted measurement framework around which cooperation and collaboration on a global scale can take place. The SI units have been under constant improvement since the 18th Century when a committee of the French Academy of Sciences introduced the first unified measurement system based on the artefacts for metre and kilogram. Recent scientific and technological advances have enabled scientists to redefine the SI units and base them entirely on fundamental properties of nature . Research is needed to make the redefined SI kelvin based on the fundamental constant of nature, the Boltzmann constant, accessible to all users.
In his presentation, Professor Machin, who has coordinated several EMPIR Joint Research Projects concerning the redefinition of the kelvin, will be drawing heavily on the research covered by the three EURAMET projects detailed below, which have each contributed to this aim for accessibility:
- EMRP project Implementing the new kelvin (SIB01, InK) addressed some of the challenges associated with practically generating and measuring thermodynamic temperature, particularly at the extremes of the international temperature scales.
- EMPIR project Implementing the new kelvin 2 (15SIB02, InK 2) has built upon the achievements of the preceding EMRP project SIB01 above by extending the capabilities developed into areas previously unexplored, such as ultralow temperatures in the range of 0.0009 K to 1 K. The new methods and data developed have completed the remaining gaps in knowledge required to ensure that the redefinition of the kelvin was achieved and could be disseminated effectively.
- Current EMPIR project Realising the redefined kelvin (18SIB02, Real-K) is working to bring the kelvin redefinition into practical reality while extending the life of current scales for use where they are needed. It will test primary thermometry approaches at temperatures greater than 1300 K and less than 25 K to kick-start the process of making these methods competitive with the defined scales. It will also extend the life of the currently defined temperature to allow time for primary thermometry methods to develop, and for thermal parameters of gases with potential for replacing mercury as a temperature reference point to be determined. Easing the transition to primary thermometry in this way should, in the long term enable in-situ traceability at lower cost, in applications such as remote monitoring in for e.g. manufacturing, meteorology and the nuclear power sector.
Professor Graham Machin said
‘The redefinition of the kelvin has provided a generational opportunity to move away from defined temperature scales and to take traceability directly from the redefined kelvin. In the long term this should lead to the development of practical primary thermometry approaches leading to traceability delivered at the point of measurement, facilitating autonomous production and reliable long-term temperature monitoring in situations as disparate as climate change and nuclear waste storage’.
EMPIR projects are co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.
EMRP joint research projects are part of EURAMET’s European Metrology Research Programme. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.
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