Chemical erosion of carbon at ITER relevant plasma fluxes: Results from the linear plasma generator Pilot-PSI

The chemical erosion of carbon was investigated in the linear plasma device Pilot-PSI for ITER divertor relevant hydrogen plasma flux densities 10(23) < Gamma < 10(25) m(-2) s(-1). The erosion was analyzed in situ by optical emission spectroscopy and post mortem by surface profilometry. The experiments indicate a threshold for the absolute carbon erosion rate as a function of plasma temperature T-e around 0.7 eV, a peak of the surface temperature around 550 degrees C, and no dependence on plasma flux density. The latter implies a flux dependence of the chemical erosion yield as Gamma(-1). The value of the chemical erosion yield at the surface temperature of maximum erosion and Gamma = 1 x 10(24) m(-2) s(-1) was 0.9% for T-e < 0.5 eV as determined by surface profilometry. (C) 2011 Elsevier B.V. All rights reserved.