Post-mortem analysis of the erosion/deposition pattern on ITER-like actively cooled W-monoblock from the WEST divertor (Phase I)

(WEST Team) Tsavalas, P.; Mergia, K.; Axiotis, M.; Benmoumen, A.; Bogdanović Radović, Ivančica; Diez, M.; Fortuna-Zaleśna, E.; Hakola, A.; Lagoyannis, A.; Martin, C.; Papadakis, D.; Siketić, Zdravko; Spychalski, M. (2026) Post-mortem analysis of the erosion/deposition pattern on ITER-like actively cooled W-monoblock from the WEST divertor (Phase I). Nuclear Fusion, 66 (3). ISSN 0029-5515

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Abstract

During Phase I of WEST operation, one of the lower divertor sectors, known as the test sector, was partially equipped with actively cooled ITER-like plasma-facing units (PFUs) made of 35 monoblocks (MBs). A visual inspection of the test sector after the C4 campaign revealed changes on the surface condition of several MBs located in the outer strike area. In this work, one of the MBs of interest, MB 28 from PFU#13, was extensively investigated focusing on fuel retention, material migration (erosion, transport, redeposition), and surface morphology. The plasma exposed surface of MB 28 exhibited four distinct zones along the toroidal direction. In the first zone, extending up to 4 mm from the leading edge (LE), the surface showed signs of erosion, with periodically spaced cracks oriented perpendicular to the LE. The second zone exhibited the highest material deposition (B, N, Fe and Cu) and fuel (D and He) retention, with the maximum deposit thickness reaching approximately 1.5 mu m. In the third zone, the deposition gradually decreased and accumulated in linear areas. The fourth zone, near the trailing edge, was marked by the maximum hydrogen (H) and carbon (C) deposition. In this zone, linear deposition areas rich in O and B were detected, running parallel to the edge. A clear correlation was observed between the deposition of B, N, Fe and Cu and the retention of D and He.

Item Type:	Article
Uncontrolled Keywords:	tungsten; actively cooled divertor; ion beam analysis; scanning electron microscopy; WEST tokamak; erosion; material deposition
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Experimental Physics
Projects:	Project title Project leader Project code Project type Implementation of activities described in the Roadmap to Fusion during Horizon Europe through a joint programme of the members of the EUROfusion consortium-EUROfusion Tonči Tadić 101052200 EK
Depositing User:	Ana Zečević
Date Deposited:	13 May 2026 13:33
URI:	https://fulir.irb.hr:/id/eprint/11947
DOI:	10.1088/1741-4326/ae3ab3

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