The ITER divertor has to exhaust the Helium ash and most of the 300 MW alpha particle power expected in ITER. These requirements, together with the needs to limit the leakage of neutral particles from the divertor to the plasma chamber, to accommodate the large thermal and electromagnetic loads during plasma disruptions, and to facilitate the remote replacement and refurbishment of the divertor, have led to the present design, which includes substantially new features not found in similar components operating in present day tokamaks.

The divertor assembly consists of 60 modules, each comprising plasma facing parts of different shapes (known as High Heat Flux Components (HHFCs)), and a support structure, the Cassette Body (CB). The HHFC's are designed to withstand cyclic thermal loads with steady state fluxes up to 20 MW/m² , and to cope with armour erosion due to the particle fluxes, material vaporisation or melting due to the energy deposition during disruption (up to 100 MJ/m² ). The CB has to provide overall mechanical stability of the system, to support and distribute the coolant to the HHFCs, and to contribute to the shielding of the vacuum vessel and the coils. The HHFCs are connected to the CB through flexible keys, which provide for the precise alignment of the plasma facing surfaces and allow easy replacement of damaged parts in the hot-cell while reducing the amount of irradiated waste.

The design concept, its physics basis and the analytical and experimental work carried out during the ITER Engineering Design Activities (EDA) have been illustrated in previous papers. Here we present the main features of the divertor final design from an engineering point of view and describe the final choices regarding layout, geometry and material selection. The assessment of the detailed design shows that the divertor is able to withstand the thermal and electromagnetic loading conditions foreseen for ITER, and that the estimated lifetime of the HHFCs, in relation to the thermal low cycle fatigue of the heat sink, or to the expected armour erosion, meets the ITER requirements.