1. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 1 LNE Center for Scientific and Industrial Metrology (CMSI) Thermal & Optical Division 29, avenue RogerHennequin 78197Trappes, France ( georges.bonnier@lne.fr ), R. Morice, J.C.Barbaras, N.Fleurence, V. LeSant, P.Ridoux, J.R.Filtz G. Bonnier Temperature Fixed Points and Thermal Effects

2. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 2 Within the frame of the EUROMET project 732, LNE have shared its activity in two parts : 1.LNE-INM (Saint-Denis) realizes new cells and take in consideration the effects of impurities 2.LNE-CMSI (Trappes is concerned with the thermal environment set up to realize the fixed point. The present paper deals uniquely with the point 2

3. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 3 Component of uncertainty linked with heat exchanges with the surrounding can be large

4. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 4 In association with a permanent heating process, a customary metal temperature fixed point is designed for :  Maintaining an enclosure at a stable temperature  Realizing uniform temperature enclosure  Affecting a known temperature value

5. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 5 Schematic representation of melting and freezing process

6. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 6 Aluminium Freezing UME Cell

7. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 7 Aluminium Freezing UME Cell

8. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 8

9. 9 Al Freeezing Point Plateau Results obtained by my Mai-Huong Vallin at LNE-INM Tx-Txbottom ; f= 0,08 Tx-Txbottom ; f= 0,14 Tx-Txbottom ; f= 0,25 Tx-Txbottom ; f= 0,40 Tx-Txbottom ; f= 0,55 Tx-Txbottom ; f= 0,63 Tx-Txbottom ; f= 0,70 Hydrostatic pressure effect

10. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 10 Indium cell Indium guard Thermometer Heat flux sensor Thermocouple Air pulsed furnace Heaters Where is located the liquid/solid interface ?

11. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 11 Temperature fixed point Design of a sealed cell

12. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 12 Percentage of remaining liquid 100% 80% 60% 50% 40% 30% 15% 0%

13. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 13

14. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 14 Percentage of liquid formed increases Melting process

15. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 15 Materialization of a temperature fixed point  Freezing /melting and permanent heating Both freezing and melting are a function of time Effect of impurities Thermal effects  Phase transition observed through calorimetric process The result is, in principle, independent of time

16. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 16 Schematic representation of a melt observed in a cryogenic sealed triple-point cell

17. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 17 Cryogenic sealed cell placed in adiabatic calorimeter

18. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 18 Hydrogen (13,8033 K) Deuterium (18,724 K) Neon (24,5561 K) Oxygen (54,3584 K) Nitrogen (63,151 K) Nitrogen (83, 8058 K) Carbon Dioxide (216, 592 K) mercury (234,3156 K) Water (273,16 K) Multicells

19. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 19 Realisation of the Silver point using a calorimetric method Simplified scheme : 1, Silver cell 2, thermal insulating material 3, positioning system 4, ceramic tube 5, radiation shields 6, heat pipe 7,cell-holding system 8, heater

20. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 20 Heater Principle of the adiabatic method used at LNE to realize ITS-90 metal fixed points

21. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 21

22. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 22 Temperature profile in the cell during heating time Solid Phase Liquid Phase Thermometer Temperature Distance

23. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 23 Aluminium freezing point, constant heat flux method

24. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 24 Aluminium freezing point. Calorimetric method

25. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 25 Indium cell Indium guard Thermometer Heat flux sensor Thermocouple Air pulsed furnace Heaters Design of the guard cell

26. Workshop « Towards more accurate fixed points » – St Denis – 23-24 November 2006 26 In summary: The principle of using the calorimetric method at any metal fixed point is established. The actual design has to be improved in order to get a final design. The final design must be easy to use. Using calorimetric method induces a better definition of a fixed point temperature.