Design and testing of the ECH upper port plug for ITER

Four ECH Upper Port Plugs are foreseen at ITER for counteracting plasma instabilities based on the injection of up to 20 MW mm-wave power at 170 GHz into the plasma. The required targeting of flux surfaces will be achieved by angular steering in the poloidal direction. The paper describes the main components of the mm-wave and structural system for the current reference design of the extended physics launcher (EPL). The mm-wave system is formed by waveguide and quasi-optical sections with a front steering system driven by a friction-less and backlash-free pneumatic system. The first tritium barrier is formed by a CVD diamond window with an indirect cooling concept that avoids direct water contact to the diamond disk and brazing material. The structure consists of the blanket shield module with the plasma facing first wall panel, the port plug frame, and the internal shield that provides adequate neutron shielding towards the launcher back-end. The key design requirements for the main structure are discussed with respect to efficient baking, to rigidity towards launcher deflection and to extraction of thermal loads. The current status of fabrication studies is presented demonstrating the feasibility of manufacturing routes for complex double wall structures. Testing of major port plug components is described in the context of dedicated test facilities and maintenance requirements.