Workshop « Towards More Accurate Fixed Points » – St Denis – november LNE Center for Scientific and Industrial Metrology (CMSI) Thermal & Optical Division 29, avenue Roger Hennequin Trappes, France Development of a new device for realizing the indium fixed-point in quasi-adiabatic conditions R. Morice G. Bonnier, J.C. Barbaras, N. Fleurence, V. Le Sant, G Le Dortz, A Lesauvage, G Failleau, P. Ridoux, J.R. Filtz

Workshop « Towards More Accurate Fixed Points » – St Denis – november Introduction Euromet 732 project WP6 Indium fixed point PTB (WP leader), LNE-CMSI, METAS LNE-CMSI general objective : Develop enclosures for realizing ITS-90 fixed point (t>0.01°C) in quasi-adiabatic conditions

Workshop « Towards More Accurate Fixed Points » – St Denis – november Assess uncertainties due to thermal parasitic effects in ITS-90 fixed points Thermal Properties of Materials programme of LNE-CMSI TP of pure metals To facilitate and to improve PRTs calibration ? 65 PRTs / year calibrated or checked at Ga, In - More simple (limited radiative heat flux …) - Wide variety of materials available up to 200 °C INDIUM FIXED POINT Introduction

Workshop « Towards More Accurate Fixed Points » – St Denis – november Fixed point cell placed in a guard containing a metal of the same nature Cell+guard system placed in a thermal enclosure Temperature of enclosure adjusted to maintain the guard in S/L transition during melt of the fixed point cell Principle – published experiments Fixed point cell melted using heat pulses Heat

Workshop « Towards More Accurate Fixed Points » – St Denis – november Fixed point cell placed in a guard containing a metal of the same nature Cell+guard system placed in a thermal enclosure Temperature of enclosure adjusted below the melting temperature of the metal Fixed point cell melted using heat pulses, in quasi-adiabatic conditions Principle - new device Additional heater to maintain permanently the guard in its phase transition Heat

Workshop « Towards More Accurate Fixed Points » – St Denis – november The project  to investigate / assess the previous principle  to understand thermal aspects of phase transition (permanent heat flux or heat pulses)  to optimise the final design Development of an experimental prototype construction (  nov 06) metrological assessment (  march 07) Development of a thermal model (  end 07) First step : experimental prototype Second step : final design (  end 07)

Workshop « Towards More Accurate Fixed Points » – St Denis – november Experimental prototype Scheme  Constructed for operation with a well known, « traditional » indium cell (LNE-INM type)  investigate phase transition using permanent heat flux method or calorimetric method (heat pulse technique)  2 indium guards, 5 guard heaters, 3 heaters for the indium cell, 1 TC/heater, 3 heat flux sensors

Workshop « Towards More Accurate Fixed Points » – St Denis – november Preliminary tests - Thermal control of the In guard (1) Method envisaged :  Furnace temperature maintained below melting temperature of indium  Melt initiated in the In guard using heat pulses (heating mode)  Detection of local presence of interface using heat pulses (detection mode)

Workshop « Towards More Accurate Fixed Points » – St Denis – november Preliminary tests - thermal control of the In guard (2) Temperature of auxilliary heater - « Heating mode »

Workshop « Towards More Accurate Fixed Points » – St Denis – november Temperature of auxilliary heater - « Detection mode » Preliminary tests - thermal control of the In guard (3) t norm = (t t -t min )/(t max -t min )

Workshop « Towards More Accurate Fixed Points » – St Denis – november Preliminary tests – In lateral guard and In cell (1)

Workshop « Towards More Accurate Fixed Points » – St Denis – november Successive melts of the In guard and In cell using permanent heat flux method Temperature displayed in the thermometer well Preliminary tests – In lateral guard and In cell (2)

Workshop « Towards More Accurate Fixed Points » – St Denis – november  Limited heat flux from auxilliary heaters  Possible detection of local L/S interface along indium cell  Possible detection of non- adiabaticity ( out of heating period) along indium cell Heat pulses technique : Heat exchange between In guard and In cell when both are melting  = (t g - t c )/R eq Heat pulse 1W / 500 J Preliminary tests – In lateral guard and In cell (3)

Workshop « Towards More Accurate Fixed Points » – St Denis – november Melt of the indium cell by heat pulses (guard in phase transition) Preliminary tests – In lateral guard and In cell (4)

Workshop « Towards More Accurate Fixed Points » – St Denis – november Experimental prototype set up Cross cut Details : In lateral guard, In cell, In upper guard

Workshop « Towards More Accurate Fixed Points » – St Denis – november Follow up …  Work currently in progress prototype now constructed assessment : confront methods, numerical model, melt / freeze uncertainties ?  Next steps final design of the setup aluminium (phD student)