Optimization of He-cooled divertor cooling fingers using a CAD-FEM method

Within the EU power plant conceptual study (PPCS), a modular He-cooled divertor concept is being investigated at the Forschungszentrum Karlsruhe to reach a heat flux of at least 10 MW/m2. The HEMJ (helium-cooled modular divertor with multiple-jet cooling) has been chosen as the reference design. It consists of a tile made of tungsten, a thimble made of tungsten-alloy, and a steel cartridge. The cooling is realized by impingement jets of high-pressure helium (10 MPa, 600 °C) through an array of small jet holes located at the top of the cartridge. Besides the jet cooling ability, thermal stresses in the tungsten parts induced by the high heat loads are regarded as important factors that limit the divertor performance and lifetime. Therefore, optimizing the finger geometry for stress reduction is indispensable. In this contribution a combined CAD-FEM method for the optimization of the geometry of the finger components will be outlined.