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

Workshop « Towards more accurate fixed points » – St Denis – November 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

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

Workshop « Towards more accurate fixed points » – St Denis – November 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

Workshop « Towards more accurate fixed points » – St Denis – November Schematic representation of melting and freezing process

Workshop « Towards more accurate fixed points » – St Denis – November Aluminium Freezing UME Cell

Workshop « Towards more accurate fixed points » – St Denis – November Aluminium Freezing UME Cell

Workshop « Towards more accurate fixed points » – St Denis – November

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

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

Workshop « Towards more accurate fixed points » – St Denis – November Temperature fixed point Design of a sealed cell

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

Workshop « Towards more accurate fixed points » – St Denis – November

Workshop « Towards more accurate fixed points » – St Denis – November Percentage of liquid formed increases Melting process

Workshop « Towards more accurate fixed points » – St Denis – November 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

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

Workshop « Towards more accurate fixed points » – St Denis – November Cryogenic sealed cell placed in adiabatic calorimeter

Workshop « Towards more accurate fixed points » – St Denis – November 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

Workshop « Towards more accurate fixed points » – St Denis – November 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

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

Workshop « Towards more accurate fixed points » – St Denis – November

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

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

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

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

Workshop « Towards more accurate fixed points » – St Denis – November 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.