Structural studies of deposited layers on JET MkII-SRP inner divertor tiles

• Deposited layers formed on JET inner divertor tiles during 1998-2004 and 2001-2004 campaigns have been investigated using secondary ion mass spectrometry (SIMS), Rutherford Backscattering (RBS) and optical microscopy. The thickness of the deposit decreases from the top of vertical tile 1 to the bottom and then increases on vertical tile 3 reaching similar to 60 mu m. There are even thicker deposits on the small sloping section of the floor tile 4 that can be accessed by the plasma at the inner divertor legs. Deposited films on divertor inner wall tiles are enriched in Be indicating chemical erosion of C and a multi-step transport of C to the shadowed area on floor tile 4. The films have generally a layered and globular structure in the areas with plasma contact.

Nyckelord

divertor

carbon based materials

beryllium

surface analysis

tritium depth profiles

re-deposition

graphite

erosion/deposition

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