High temperature fixed points for future temperature scale

Project Description

There has been a long-standing requirement for high temperature fixed-points above the copper point for improving both thermometry and radiometry. With the advent of metal-carbon eutectics as high temperature fixed-points (HTFP) it is now clear that this requirement can be met. This programme of research aims to overcome the technical barriers that remain in turning these new fixed-points into fully-fledged metrology tools for general use by the world metrology community.

The project is broken down into seven workpackages these with a brief outline of the technical content.

• Confirm long term stability and robustness of the high temperature fixed-points (WP1, LNE-INM/Cnam)
• Develop fixed-point construction methodology to ensure intra-cell repeatability at the sub-100 mK level, construct set of definitive cells (WP2, NMIJ)
• Clearly understand the furnace/fixed-point/pyrometer interactions, and quantify associated uncertainties (WP2, NMIJ)
• Assessment and improvement of absolute thermometry capability of all participants (WP4, PTB)
• Multilateral assignment of thermodynamic temperatures to be a set of high quality reference high temperature fixed-point cells (WP5, NPL)
• Recommendations to CCT how to revise ITS-90 to make step change improvement in high temperature thermometry (WP6, NPL)
   

One of the project partners is ex-EU but is committed to the projects objectives
Besides the named WP leaders other laboratories are involved in the research these are: NMIA, VNIIOFI, KRISS, NIST and NIM (Australia, Russia, South Korea, USA and China)

Final Report 2012-03-05

There has been a long-standing requirement for high temperature fixed-points above the copper point for improving both thermometry and radiometry. This project is to move this technology from research to implementation into main-stream metrology.  This work was being undertaken as part of the CCT-WG5 HTFP research plan. From Summer 2012 this work will be subsumed into the EMRP Implementing the new Kelvin (InK) project and hence this is the final report of E-926.

Progress in 2011 has been:

• WP1: Long term stability measurements. It was found that Co-C was stable. However Pt-C and Re-C gave inconclusive results due to robustness and CC sheet erosion problems. These findings led to crucible redesigns to fix these problems [INM-CNAM].
• A number of HTFPs of Co-C, Pt-C and Re-C (and Cu) have been made and their performance measured. Four of each will be selected, at a special meeting at ITS9, Mar 12, to enter the T assignment phase (WP5).[NMIJ]
• Primary radiometry measurements of Co-C, Pt-C and Re-C have been reported by the WP participants from the  participating laboratories of WP4. These results will be presented at ITS9 in Mar 12 and guidance for improved primary radiometry given. [PTB]
• WP5 has been assimulated as WP1 of the InK project. T assignment will be performed in 2012-2015. A draft of the protocol for WP5 has been written. [NPL]
   

A significant number of papers, including a keynote address, related to the work of EURAMET Project 926/CCT-WG5 research plan were presented at ITS9, California, USA, 2012.