Fabrication and testing of W7-X pre-series target elements

Böswirth

Journal of Nuclear Materials

et al. 2009

Extensive high heat flux cycling testing of pre-series targets was performed in the neutral beam facility GLADIS to establish the industrial process for the manufacturing of 890 targets, which will be needed for the installation of the WENDELSTEIN 7-X divertor. The targets are manufactured of flat tiles of CFC NB31 as plasma facing material bonded by an Active Metal Casting copper interlayer onto a water-cooled CuCrZr structure. Based on the results of the 3D thermo-mechanical FEM analysis of the CFC/Cu interface, an additional set of 17 full-scale pre-series elements including three design variations was manufactured by PLANSEE SE. The insertion of an additional plastically compliant copper interlayer between the cooling structure and the Active Metal Casting interlayer showed the best results. No critical tile detachment was observed during >5000 cycles at 10 MW/m². These results demonstrated the sufficient life time of the component for the expected heat load in operation.

Section: Variants Of Manufactured Cfc/cu-bondingmentioning

confidence: 99%

Cyclic heat load testing of improved CFC/Cu bonding for the W 7-X divertor targets

Böswirth

Journal of Nuclear Materials

et al. 2009

“…The monoblock geometry always induces a thermal gradient between the outer edges and the centre of the CFC blocks. A misalignment in the orientation of the carbon fiber mesh during production of the CFC results in further asymmetries of the surface temperature [12], [13]. Therefore, the resulting surface temperature distribution is not uniform as expected from the Gaussian distributed heat load.…”

Section: High Heat Flux Test Campaignmentioning

confidence: 99%

Design and Test of Wendelstein 7-X Water-Cooled Divertor Scraper

IEEE Trans. Plasma Sci.

Ehrke

et al. 2018

Abstract-Heat load calculations have indicated the possible overloading of the ends of the water-cooled divertor facing the pumping gap beyond their technological limit. The intention of the scraper is the interception of some of the plasma fluxes both upstream and downstream before they reach the divertor surface. The scraper is divided into six modules of four plasma facing components (PFCs); each module has four PFCs hydraulically connected in series by two water boxes (inlet and outlet). A full-scale prototype of one module has been manufactured. Development activities have been carried out to connect the water boxes to the cooling pipes of the PFCs by tungsten inert gas internal orbital welding. This prototype was successfully tested in the GLADIS facility with 17 MW/m2 for 500 cycles. The results of these activities have confirmed the possible technological basis for a fabrication of the water-cooled scraper.

“…The acceptance criteria are the same as for the W7-X divertor target elements [8]: a leak rate lower than 5 × 10 −7 Pa l/s at room temperature and 3.2 MPa internal He pressure, and a leak rate lower than 5 × 10 −6 Pa l/s at 160 • C and 2.5 MPa internal He pressure.…”

Section: Full-scale Pfc Prototypementioning

confidence: 99%

Prototyping phase of the high heat flux scraper element of Wendelstein 7-X

Fusion Engineering and Design

Ehrke

et al. 2016

h i g h l i g h t s• Aim of scraper element: reduction of heat loads on high heat flux divertor ends.• Design: actively water-cooled for 20 MW/m 2 local heat loads.• Technology: CFC NB31 monoblocks bonded by HIP to CuCrZr cooling tube.• Successful high heat flux testing up to 20 MW/m 2 . a b s t r a c tThe water-cooled high heat flux scraper element aims to reduce excessive heat loads on the target element ends of the actively cooled divertor of Wendelstein 7-X. Its purpose is to intercept some of the plasma fluxes both upstream and downstream before they reach the divertor surface. The scraper element has 24 identical plasma facing components (PFCs) divided into 6 modules. One module has 4 PFCs hydraulically connected in series by 2 water boxes. A PFC, 247 mm long and 28 mm wide, has 13 monoblocks made of CFC NB31 bonded by hot isostatic pressing onto a CuCrZr cooling tube equipped with a copper twisted tape. 4 full-scale prototypes of PFCs have been successfully tested in the GLADIS facility up to 20 MW/m 2 . The difference observed between measured and calculated surface temperatures is probably due to the inhomogeneity of CFC properties. The design of the water box prototypes has been detailed to allow the junction between the cooling pipe of the PFCs and the water boxes by internal orbital welding. The prototypes are presently under fabrication.