Comparison of erosion and deposition in JET divertor during the first three ITER-like wall campaigns

• Published in: Physica scripta Vol. T171; no. 1; pp. 14059 - 14066
• Main Authors: Krat, S, Mayer, M, Baron-Wiechec, A, Brezinsek, S, Coad, P, Gasparyan, Yu, Heinola, K, Jepu, I, Likonen, J, Petersson, P, Ruset, C, de Saint-Aubin, G, Widdowson, A, JET contributors
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.01.2020
• Subjects: beryllium; deposition; erosion; hydrogen accumulation; ion beam analysis; JET-ILW; tungsten
• ISSN: 0031-8949; 1402-4896; 1402-4896
• DOI: 10.1088/1402-4896/ab5c11

The manuscript presents an overview of the erosion and deposition data in the inner and outer JET divertor observed during the first three ITER-like wall campaigns (JET-ILW1, JET-ILW2, JET-ILW3). Erosion and deposition were studied using core samples cut out from divertor tiles. For the studied samples a similar general deposition pattern was observed in all three campaigns: More than 60% of the total deposition occurred in the upper region of the inner divertor on tiles 0 and 1, where Be was transported and deposited from the scrape-off layer. High erosion was observed only on tile 5. In JET-ILW2 and 3, erosion together with high power fluxes was observed in the outer divertor at the bottom of tile 7. Additionally, deposition peaks were observed on the sloping parts of tiles 4 and 6, which were more pronounced in JET-ILW2 and 3 due to placing the strike point more often on these tiles. The deposits consisted primarily of Be, with some additional D and C. Deposition rates were observed to decrease from campaign to campaign, with the C deposition rate decreasing the most, more than 2 times from JET-ILW1 to JET-ILW3. D retention up to levels of ∼1 at% was observed up to large depths in the W protective coatings in all campaigns.