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, Jari Likonen, J. Pettersson, Seppo Koivuranta, A.M. Widdowson, JET Contributors

    Research output: Contribution to journalArticleScientificpeer-review

    9 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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