Calculation of heat flux and evolution of equivalent thermal contact resistance of carbon deposits on Tore Supra neutralizer

This paper presents anew heat flux computation applied to the neutralizer of Tore Supra using a deconvolution procedure and the thermal quadrupoles method. A steady deposition of carbon takes place at a rate of about 30 nm/s on the actively cooled carbon fibre composite (CFC) surface of the neutralizer. Thermal measurements of the surface temperature are available through optical fibre-based infrared thermography. These measurements are used to estimate the heat flux and to follow the temporal evolution of a single parameter, representing the thermal properties of the growing thin carbon layer. This parameter corresponds to an equivalent thermal resistance R-eq (in m(2) KW-1). During the first 2000s of plasma operation on a new CFC neutralizer surface, R-eq rises about proportionally with exposure time. From then on no significant further evolution of R-eq is observed. We interpret this as indication for a thermal and mechanical detachment of the deposit from the substrate for deposits exceeding a thickness of 60 mu m. (C) 2008 Elsevier B.V. All rights reserved.