Evolution of carbon tiles during repetitive long pulse operation in Tore Supra

Two experimental campaigns (2001 and 2002) have been carried out with the tokamak Tore Supra since the complete upgrade of all plasma facing components. The toroidal pumped limiter (TPL) allows reliable steady state operation at significant injected power (up to 8.5 MW peak, 4.3 minutes at 3 MW). One of the first and main result is related to the abundance and diversity of carbonaceous deposits on plasma facing surfaces. They have been observed on the TPL on surfaces close to the plasma frontier. On neutralizers located at pumping ducts under the limiter, a layer builds up rapidly and the thickness reach 840 μm after 2.3 hours of plasma. These deposits and layers distort the infrared measures and the deduction of the incident heat flux from the temperature is difficult. A simple 1D thermal calculation tool linked to the database has been developed and is used to allow flexible analysis. On the TPL, the aim is to evaluate the ageing of the bond between the tile and the metallic cooling structure from the surface temperature measurement. So far, no evidence of ageing has been observed after the two first years of operation. (authors)