The MkII gas box divertor - a new design concept

Publisher Summary This chapter discusses the extensive screening tests that have been performed during material selection for MkI and MkII divertors. For structural applications, a quasi 3-D material with nearly isotropic thermal conductivity was chosen. Two grades — SEPCARB N11-2 and N11 — were selected. The design used for the inner and outer carriers is discussed in the chapter. An arrangement of ribs, webs, and plates is used to produce a lightweight, rigid assembly. The target plate tiles are located on to the carriers with alignment dowels and tension bolts loaded with disc springs. Four corner support pads are machined at each tile location to define accurately the tile height with reference to the adjacent tiles for shadowing. The manufacturing sequence has to take into account the large number of accurately fitting interfaces that must locate simultaneously to engage all the alignment dowels. Design of the divertor carriers has had to maintain remote handling (RH) capability from the beginning. The side and base carriers have RH lifting points on the top plates while the septum is moved by a special jig locating off the top plate and steps in the ribs.