3D finite element electromagnetic and stress analyses of the JET LB-SRP divertor element (tungsten lamella design)

Within the ITER-like wall project at Joint European Torus (JET), the original plasma facing tiles in the divertor region made of carbon fibre composite (CFC) will be replaced by tungsten coated CFC and bulk tungsten tiles. The main constraint of the bulk tungsten concept is to accommodate the power and energy handling requirements, the electromagnetic (EM) forces and the mechanical requirements of the existing remote handling system.Through a number of intermediate design options the "lamella" option has been developed, consisting of plasma facing tiles, an inconel wedge holding the tiles and an inconel interface plate attaching the wedge to the JET CFC base plate. In order to minimize eddy currents the wedge must be equipped with slits and the W-lamellae are isolated from each other. Defined electrical contacts from the lamellae via the wedge to the base plate define the path of the halo currents. The pairs of lamellae are isolated from each other by insulating spacers and tie rods keep the stack of tungsten lamellae and ceramic-coated spacers together. Eight tungsten lamella stacks are attached to the wedge via eight "rails." This paper reports on calculation of the electromagnetic (EM) loads in the block components and of the stress-strain state of the block, subjected to the worst combination of EM loads, by 3D finite element (FE) electromagnetic and stress analyses.As a result of these studies the level of initial pre-tension of the joint elements has been checked against possible detachment. The bending of the load bearing components has proved to be moderately low compared with the structural material allowable limits. (C) 2007 Elsevier B.V. All rights reserved