Erosion/redeposition analysis of the ITER first wall with convective and non-convective plasma transport

Sputtering erosion/redeposition is analyzed for ITER plasma facing components, with scrape-off layer (SOL) plasma convective radial transport and non-convective (diffusion-only) transport. The analysis uses the UEDGE and DEGAS codes to compute plasma SOL profiles and ion and neutral fluxes to the wall, TRIM-SP code to compute sputter yields, and REDEP/WBC code package for 3-D kinetic modeling of sputtered particle transport. Convective transport is modeled for the background plasma by a radially-varying outward-flow component of the fluid velocity, and for the impurity ions by three models designed to bracket existing models/data. We report here results for the first wall with the reference beryllium coating and an alternative tungsten coating. The analysis shows: 1) sputtering erosion for convective flow is 20-40 times higher than for diffusion-only but acceptably low (~0.3 nm/s) for beryllium, and very low (~.002 nm/s) for tungsten; 2) plasma contamination by wall sputtering, with convective flow, is of order 1% for beryllium and negligible for tungsten; 3) wall-to-divertor beryllium transport may be significant (~10-60% of the sputtered Be current); 4) tritium codeposition in redeposited beryllium may be high (~1-6 gT/400s pulse).