Structural design of the iter ec upper launcher

Abstract

To counteract plasma instabilities, Electron Cyclotron launchers with a total Millimeter-wave power of 20 MW are installed into four of the ITER Upper Ports. Each Mm-wave-system consists of eight transmission lines; a quasi-optical focusing mirror system and two steerable front mirrors to be capable of injecting the beams over the range plasma instabilities are susceptible to occur. The Mm-wave-systems are mounted into a stainless steel cask which has to meet the demands on precise alignment; high-performance cooling for substantial nuclear heat loads; mechanical strength to sustain plasma disruptions and proper nuclear shielding. A structural system of two main components was investigated on a conceptual level. It is composed of the Blanket Shield Module (BSM) and the launcher mainframe. A removable flange connection between the BSM and the main frame provides access to the launcher internals. The entire system is attached to the standard ITER Port interface. Appropriate remote handling capability is also considered. For the BSM and the front segment of the main frame a rigid double wall structure with meandering rectangular cooling channels was designed. The rear part of the main frame consists of a single wall element with individual openings to simplify maintenance access. A shielding concept which serves also as an optical bench for the Millimeter-wave system was developed. Analyses regarding mechanical strength, thermo-hydraulic behavior, baking capability and shielding efficiency were performed. To investigate industrial manufacturing routes, several prototypes of characteristic sections of the BSM and the main frame were manufactured. They are under study at the Launcher Handling Test facility (LHT) at FZK, which is able to simulate different ITER operating conditions. Extensive test series were performed to validate underlying analysis related to temperature distribution, pressure drop within the cooling paths and removal of applied heat loads.