Chemical sputtering from the pump limiter neutralizer in Tore Supra

Carbon is widely used as plasma facing component in present fusion devices and is proposed for the divertor plates of ITER. The improvement in the control of the plasma edge parameters, limiting the power flux and the electron temperature in the divertor leads to an acceptable erosion rate of carbon due to physical sputtering and radiation enhanced sublimation. In these conditions, chemical sputtering will probably be the main mechanism of erosion for the carbon plate. Tn situ measurements of hydrocarbon production on the neutralizer plate of an outboard pump limiter have been obtained in Tore Supra. CD4 has been monitored by means of optical spectroscopy and mass spectrometry for different electron temperatures and densities. Simulations performed with a Monte Carlo code (BBQ), show a good agreement with experimental data at high flux, low electron temperature. (C) 1999 Elsevier Science B.V. All rights reserved.