Impurity re-distribution in the corner regions of the JET divertor

A. Widdowson (Corresponding Author), J. Likonen, JET Contributors

    Research output: Contribution to journalArticle in a proceedings journalScientificpeer-review

    3 Citations (Scopus)

    Abstract

    The International Thermonuclear Experimental Reactor (ITER) will use a mixture of deuterium (D) and tritium (T) as the fuel to generate power. Since T is both radioactive and expensive the Joint European Torus (JET) has been at the forefront of research to discover how much T is used and where it may be retained within the main reaction chamber. Until the year 2010 the JET plasma facing components were constructed of carbon fibre composites. During the JET carbon (C) phases impurities accumulated at the corners of the divertor located towards the bottom of the chamber in regions shadowed from the plasma where they are very difficult to reach and remove. This build-up of C and the associated H-isotope (including T) retention were of particular concern for future fusion reactors therefore, in 2010 JET changed the wall protection to (mainly) Be and the divertor to tungsten (W)-the JET ITER-like wall (ILW)-the choice of materials for ITER. This paper reveals that with the JET ILW impurities are still accumulating in the shadowed regions, with Be being the majority element, though the overall quantities are very much reduced from those in the C phases. Material will be transported into the shadowed regions principally when the plasma strike points are on the corner tiles, but particles typically have about a 75% probability of reflection from line-of sight surfaces, and multiple reflection/scattering results in deposition over all surfaces.

    Original languageEnglish
    Article number014060
    JournalPhysica Scripta
    Volume2017
    Issue numberT170
    DOIs
    Publication statusPublished - 1 Dec 2017
    MoE publication typeA4 Article in a conference publication
    Event16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, PFMC 2017 - Neuss/Dusseldorf, Germany
    Duration: 16 May 201719 May 2017

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    Keywords

    • Beryllium
    • Deposition
    • Impurities
    • JET

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