Author/Authors :
Rudakov، نويسنده , , D.L. and Boedo، نويسنده , , J.A. and Yu، نويسنده , , J.H. and Brooks، نويسنده , , N.H. and Fenstermacher، نويسنده , , M.E. and Groth، نويسنده , , M. and Hollmann، نويسنده , , E.M. and Lasnier، نويسنده , , C.J. and McLean، نويسنده , , A.G. and Moyer، نويسنده , , R.A. and Stangeby، نويسنده , , P.C. and Tynan، نويسنده , , G.R. and Wampler، نويسنده , , W.R. and Watkins، نويسنده , , J.G. and West، نويسنده , , W.P. and Wong، نويسنده , , C.P.C. and Bastasz، نويسنده , , R.J. and Buchenauer، نويسنده , , D. A. Whaley، نويسنده , , J.، نويسنده ,
Abstract :
Erosion of the main chamber plasma-facing components is of concern for ITER. Plasma interaction with the outboard chamber wall is studied in DIII-D using Langmuir probes and optical diagnostics. Fast camera data shows that edge localized modes (ELMs) feature helical filamentary structures propagating towards the outboard wall. Upon reaching the wall, filaments result in regions of local intense plasma–material interaction (PMI) where peak incident particle and heat fluxes are up to two orders of magnitude higher than those between ELMs. In low density/collisionality H-mode discharges, PMI at the outboard wall is almost entirely due to ELMs. A moderate change of the gap between the separatrix and the outer wall strongly affects PMI intensity at the wall. Material samples exposed near the outboard wall showed net carbon deposition in high-density discharges (near the Greenwald limit) and tendency towards net erosion in lower density discharges (∼0.45 of the Greenwald limit).
