Structural evaluation of a compact, semi-closed W-shaped divertor system for JT-60U

A compact, semi-closed W-shaped divertor system has been designed, fabricat ed and installed in the JT-60U to replace the open divertor system. The new system consists of inclined diverters, a dome and baffles. To meet the str uctural requirements, a segmented structure with an electrically insulated flexible gas seal was applied. Using FEM codes, the system's structural int egrity was confirmed for the plasma disruptions by electromagnetic and stru ctural analyses, which take into account the effect of halo currents. Subst antial reduction of induced electromagnetic forces is attained in the diver tor system due to the electrical insulation used for the gas seal structure . In addition, because of its segmented structure, the induced electromagne tic forces on each component unit are found to be limited. The maximum stre ss intensities and their ranges are obtained within allowable values. Therm al stress arising from the temperature difference between the divertor syst em and the vacuum vessel during the baking operation is also satisfactory. Furthermore, thermal and thermal stress analyses showed that the plasma fac ing components have sufficient structural integrity. (C) 1999 Elsevier Scie nce S.A. All rights reserved.