A modular He-cooled divertor concept for DEMO is being investigated at Forschungszentrum Karlsruhe (FZK) within the framework of the EU power plant conceptual study. The design goal is to reach a ...heat flux of at least 10 MW/m 2 . The reference divertor design is based on the use of a tungsten tile which is brazed to a thimble made of W-1 wt%La 2 O 3 cooled by helium impingement jets. The current divertor work programme focuses on manufacture and high-heat-flux tests of prototypical tungsten mock-ups to demonstrate the manufacturability and the performance of the design. Till now three high-heat-flux test series on 1-finger mock-ups were successfully performed in a combined helium loop and TSEFEY facility at Efremov. Technological study on fabrication of a 9-finger module of stain less steel was carried out. First gas flow tests showed uniform mass flow rate distribution which agrees well with calculation results. These initial test results confirm the performance of this concept and serve as a strong basis for further development of the material and concept and more integrated testing.
A modular He-cooled divertor concept for DEMO has been developed at Forschungszentrum Karlsruhe in cooperation with the Efremov Institute. The work covers the areas of design, analyses, fabrication ...technology, and experimental design verification. The overall design goal is to reach a heat flux of 10 MW/m 2 at least. The selected reference design HEMJ (He-cooled modular divertor with multiple-jet cooling) employs small tiles made of tungsten, which are brazed to a finger-like thimble structure, which is made of tungsten alloy. The finger module is cooled by multiple jets of helium (10 MPa, 634degC) directly impinging onto the inner heated surface of the thimble. For the experimental verification of the design, a combined facility at Efremov, comprising a helium loop and an electron beam facility, was used. Technological studies focussed on the fabrication of tungsten divertor mock-ups, combined with an Eurofer steel structure. The first series of 1-finger mock-ups manufactured in this way were successfully HHF-tested in 2006. The test results confirmed the feasibility and the required performance of the design. The 2007 test series use mock-ups which have been improved in terms of thermal stress reduction and increasing manufacturing quality of tungsten parts (tile and thimble) and show a tendency of lifetime enhancement, i.e. surviving larger thermal cycles.
