Numerical estimates of the ITER first mirrors degradation due to atomic fluxes

A systematic numerical study of the deposition of Be and C atoms on the ITER main chamber first mirrors and their erosion due to fast D(T) atoms has been carried out. The calculations are based on Monte-Carlo neutral transport modelling (with the EIRENE code) on a simulated steady-state plasma background. A generic reduced model of cylindrical and conical diagnostic ducts is considered. The results indicate that the sputtering of the mirrors can be made acceptably small if they are installed in sufficiently long ducts. At the same time the deposition of impurities can be a serious issue even for mirrors protected in long channels. However, the calculations of deposition are not very reliable at the current stage and a need to seriously improve them is indicated.