Open AccessMolybdenum erosion measurements in Alcator C-Mod
Author(s) -
W.R. Wampler,
B. LaBombard,
B. Lipshultz,
Dimitri Pappas,
C.S. Pitcher,
G.M. McCracken
Publication year - 1998
Language(s) - English
Resource type - Reports
DOI - 10.2172/658416
Subject(s) - alcator c mod , divertor , molybdenum , erosion , sputtering , impurity , tokamak , materials science , plasma , langmuir probe , analytical chemistry (journal) , metallurgy , chemistry , nuclear physics , thin film , geology , plasma diagnostics , physics , geomorphology , organic chemistry , nanotechnology , chromatography
Erosion of molybdenum was measured on a set of 21 tiles after a run campaign of 1,090 shots in the Alcator C-Mod tokamak. The net erosion of molybdenum, was determined from changes in the depth of a thin chromium marker layer measured by Rutherford backscattering. Net Mo erosion was found to be approximately 150 nm near the outer divertor strike point, and much less everywhere else. Gross erosion rates by sputtering were estimated using ion energies and fluxes obtained from Langmuir probe measurements of edge-plasma conditions. Predicted net erosion using calculated gross erosion with prompt redeposition and measured net erosion agree within a factor of 3. Sputtering by boron and molybdenum impurities dominates erosion