Fusion Science and Technology / Volume 56 / Number 2 / August 2009 / Pages 1013-1017
Divertors and High Heat Flux Components / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)
A He-cooled divertor concept for DEMO has been pursued at Forschungszentrum Karlsruhe within the framework of the EU power plant conceptual study. The design goal is to achieve a DEMO-relevant heat flux of at least 10 MW/m2. The HEMJ (He-cooled modular divertor with multiple-jet cooling) was chosen as the reference concept. It employs small tiles made of tungsten, which are brazed to a thimble made of tungsten alloy W-1%La2O3. The W finger units are connected to the main structure of ODS Eurofer steel by means of a transition piece. The divertor modules are cooled by helium jets (10 MPa, 600°C) impinging onto the heated surface of the thimble. In cooperation with the Efremov Institute a combined helium loop & electron beam facility (60 kW, 27 keV) was built in St. Petersburg, Russia, for experimental verification of the design. Technological studies were performed on manufacturing of the W finger mock-ups. The results of high heat flux (HHF) tests till now confirm the divertor performance required. The knowledge gained from these experiments and some aspects on the design improvement are discussed in this contribution.