THE DETERMINATION OF THE SEEBECK COEFFICIENTS OF SOME COMMON THERMOCOUPLE WIRES USING EPITHERMAL NEUTRON RESONANCE BROADENING. S. M. Clark, R. L. Jones, R. te-Lindert, D. Walker¹, M. C. Johnson¹, P. Fowler², CCLRC, Daresbury Laboratory, Warrington, WA4 4AD, UK, ¹Lamont-Doherty Geological Obs., Columbia University, Palisades, New York, 10964, USA, ²H. H. Wills Phys. Lab., University of Bristol, Bristol, BS8 1TL, UK

Thermocouples provide the only means of determining temperature in large volume high pressure cells. The effect of temperature on thermocouple emfs was not previously known above 3.5GPa. We have determined the effect of pressure on thermocouple emfs up to 1 2GPa and 1 700deg.C using epithermal neutron resonance broadening as an in-situ pyrometric technique. A Walker high pressure cell with a 10,000kN hydraulic ram was used for the generation of high temperatures and pressures. Data were collected on the TEST station of the ISIS spallation neutron source. Details of the experimental technique and data analysis procedures will be given together with details of the emf corrections.