Deep deuterium retention and Be/W mixing at tungsten coated surfaces in the JET divertor

H. Bergsker, I. Bykov, Y. Zhou, P. Petersson, G. Possnert, J. Likonen, J. Pettersson, S. Koivuranta, A.M. Widdowson

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    7 Citations (Scopus)


    Surface samples from a full poloidal set of divertor tiles exposed in JET through operations 2010-2012 with ITER-like wall have been investigated using SEM, SIMS, ICP-AES analysis and micro beam nuclear reaction analysis (µ-NRA). Deposition of Be and retention of D is microscopically inhomogeneous. With careful overlaying of µ-NRA elemental maps with SEM images, it is possible to separate surface roughness effects from depth profiles at microscopically flat surface regions, without pits. With (3He, p) µ-NRA at 3-5 MeV beam energy the accessible depth for D analysis in W is about 9 µm, sufficient to access the W/Mo and Mo/W interfaces in the coatings and beyond, while for Be in W it is about 6 µm. In these conditions, at all plasma wetted surfaces, D was found throughout the whole accessible depth at concentrations in the range 0.2-0.7 at% in W. Deuterium was found to be preferentially trapped at the W/Mo and Mo/W interfaces. Comparison is made with SIMS profiling, which also shows significant D trapping at the W/Mo interface. Mixing of Be and W occurs mainly in deposited layers.
    Original languageEnglish
    Article number014061
    Number of pages8
    JournalPhysica Scripta
    Issue numberT167
    Publication statusPublished - 2016
    MoE publication typeA1 Journal article-refereed


    • beryllium
    • deuterium
    • ion beam analysis
    • materials migration


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