Chemical sputtering of carbon in Tore-Supra outboard pump limiter

The use of a large amount of carbon in tokamaks induces two major problems mainly due to the chemical sputtering: erosion and tritium retention. In the Tore-Supra outboard pump limiter, the in situ chemical sputtering yield of the carbon neutralizer plate has been studied. Investigation of methane and heavier hydrocarbon (C2Dx and C3Dy) emission has been performed in ohmic and lower hybrid heated discharges, by means of mass spectrometry and optical spectroscopy. Simulation performed with a Monte Carlo code (BBQ) allows validation of the sputtering yield calculation method and show good agreement with experimental data.