5-9 September 2016
Prague Congress Centre
Europe/Prague timezone

O4B.1 Potential approach of IR-analysis for HHF quality assessment of ITER tungsten divertor targets

8 Sep 2016, 11:00
20m
Meeting Hall I 1st floor (Prague Congress Centre)

Meeting Hall I 1st floor

Prague Congress Centre

5. května 65, Prague, Czech Republic
Board: 1
Oral F. Plasma Facing Components O4B

Speaker

Henri Greuner (Max-Planck-Institut für Plasmaphysik)

Description

Plasma-facing units equipped with tungsten (W) monoblock geometry are employed at the vertical targets of the ITER divertor. This contribution discusses a statistical approach for high heat flux (HHF) tests as potential quality assessment of the ITER divertor additional to the quality assurance performed by the manufacturer during the manufacturing. The IR analysis of the local temperature evolution of W blocks during the first 100 cycles at 10MW/m² could be statistically assessed. This would allow an assessment of the industrially manufactured plasma facing units, equipped with roughly 300.000 monoblocks with reasonable HHF test effort. We discuss a possible approach on the basis of the HHF test strategy of W7-X divertor manufacturing [1]. Ten monoblock mock-ups with different surface machining and varying geometries were loaded with 100 cycles at 10MW/m² in the test facility GLADIS. The surface temperature evolution was monitored with both, two-colour pyrometry and IR imaging. While the pyrometer data showed reasonable temperatures in a good agreement with 3D-FE modelling, the raw temperature IR data continuously decreased with cycle number. Temperature differences up to 200K between pyrometer and IR camera data were measured. This effect originated from removal of surface impurities and was confirmed by EDX analysis. The monoblock geometry as well as the crucial emissivity of W require a careful evaluation of the proposed method. At least two parameters describe the position and extension of a bonding defect between cooling-tube and monoblock, the circumferential position θ and the extension Δθ. According to the 3D-FE modelling of a monoblock with a large defect Δθ=30°, a local surface temperature increase between 30 and 100K has to be measured. We discuss a possible correction method of the IR-data. Possible assessment criteria based on these temperature measurements will be presented. [1] H.Greuner et al., FED 88 (2013) 581-584

Co-authors

Bernd Boswirth (Max-Planck-Institut für Plasmaphysik, Boltzmannstr.2, 85748 Garching, Germany) Hans Maier (Max-Planck-Institut für Plasmaphysik, Boltzmannstr.2, 85748 Garching, Germany) Henri Greuner (Max-Planck-Institut für Plasmaphysik, Boltzmannstr.2, 85748 Garching, Germany) Stephanie Panayotis (ITER Organization, Route de Vinon sur Verdon, F-13067 Saint Paul lez Durance, France) Takeshi Hirai (ITER Organization, Route de Vinon sur Verdon, F-13067 Saint Paul lez Durance, France) Udo v. Toussaint (Max-Planck-Institut für Plasmaphysik, Boltzmannstr.2, 85748 Garching, Germany)

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