Material transport from marker tiles in the JET divertor

Abstract

For each of the three JET ILW campaigns a few special marker tiles were placed in the divertor. Amongst the W-coated CFC tiles are tiles coated with a ∼ 3 µm layer of Mo with a ∼ 4 µm topcoat of W and tiles with just a ∼ 4 µm layer of Mo to measure erosion and re-deposition.During ILW1 just one Mo marker tile was included in the inner divertor band of Tiles 3. After ILW1 the Mo marker was removed for analysis and inter alia two W-coated Tiles 4 to check for re-deposited Mo. About 7% of the Mo removed from the Tile 3 Mo marker was found on band 4 tiles.A fresh Mo marker Tile 3 was inserted in for ILW2 + 3 plus a Mo marker Tile 4 for ILW2 (after which it was removed for analysis). Tile 4 removed after ILW3 was measured for Mo re-deposition. The Mo deposition pattern on Tile 4 with a regular W topcoat was quite different to that after ILW1, with much more Mo located towards the corner of the divertor.