Abstract

A test assembly of carbon coated molybdenum tiles was exposed to a sequence of well-diagnosed ohmic helium discharges in the Experimental Advanced Superconducting Tokamak (EAST) using the material and plasma evaluation system. The test assembly was configured to approximate, on a reduced scale, the profile of a first-wall panel in ITER. Net erosion and deposition of carbon was determined from measurements of the thickness of a carbon surface layer by ion-beam analysis before and after the plasma exposure. The highest erosion of 800 nm, or about one third of the initial thickness, occurred near the EAST midplane on the side facing the ion-drift direction. Erosion decreased in toroidal and poloidal directions with increasing distance from the plasma. Net deposition was not observed anywhere above the limit of detection. This experiment provides data needed to benchmark codes being used to predict erosion/deposition in ITER.

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