The Eurofusion-DEMO design will complete the Pre Conceptual Design phase (PCD) with a PCD Gate, named G1, scheduled to take place in Q4 2020 that will focus on assessing the feasibility of the plant and its main components prior to entering into the Conceptual Design phase. In the paper first an overview is given of the Eurofusion-DEMO Divertor Assembly including design and interface description, systems and functional requirements, load specification, system classification, manufacturing procedures and cost estimate. Then critical issues are discussed and potential design solutions are proposed, e.g.: -Neutron material damage limits of the different (structural) materials present in the divertor assembly (as CuCrZr, Eurofer) and in the vacuum vessel (AISI 316L(N)-IG); -Temperature hot spots in parts of the divertor assembly exposed to high nuclear heating and high heat radiation (from the plasma core or the separatrix) causing difficulties for active or passive cooling (e.g. cassette body structure, liner support structures, mechanical supports, divertor toroidal rails); -Arrangement and design of plasma-facing components and liner with pumping slot in the divertor cassette to enable pumping of exhaust gases from the lower port.

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The exhaust of power and particles is currently considered as one of the ultimate challenges in view of the design of a power producing magnetic confinement thermonuclear fusion device, like DEMO. One predominantly challenging aspect in this regard is the design and manufacture of divertor target plasma-facing components (PFCs) that have to sustain substantial particle, heat and neutron fluxes during fusion operation. With respect to the design of highly loaded actively cooled PFCs, copper (Cu) alloys are currently regarded as state-of-the-art structural heat sink materials. However, it has been underlined that the use of Cu alloys in PFCs implies issues mainly due to the behaviour of these materials under neutron irradiation characterised by a pronounced loss of ductility at lower and a loss of strength at elevated temperatures. These operating temperature limitations impose a strong constraint on the design of divertor PFCs and have regarding DEMO in the literature been termed a high impact design engineering risk. Against this background, the development of tungsten-copper (W-Cu) composites as potentially advanced heat sink materials for highly loaded PFCs was pursued by the authors during recent years. The progress of these developments is discussed in the present paper in terms of results of high-heat-flux tests conducted on PFC mock-ups that comprised W-Cu composite material heat sinks. Overall, the results of these tests indicate that W-Cu composites can indeed be regarded a viable class of advanced materials for the heat sink of highly loaded PFCs.

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The divertor is one of the most challenging components for DEMO reactor both from the design and fabrication technology point of view, since it must be capable to withstand the high heat fluxes (HHF) expected during normal operation (up to 10 MW/m²) and slow transient events (up to 20 MW/m²), like loss of plasma detachment. Within the frame of the EUROfusion Consortium the "Target development" subproject inside the Work Package 'Divertor' (WPDIV) has been dedicated to achieve this performance studying different concepts.ENEA focused on the "ITER-like" target that consists of applying the ITER design and fabrication technology to DEMO targets. The ITER-like concept mock-up was at first designed and optimized by FE analysis then manufactured and checked by non-destructive testing (NDT), finally thermal fatigue testing (TFT) and destructive testing (DT) were performed too .This paper reports the comparison of the thermal behavior of the ITER-like mock-ups between the analysis performed using ANSYS-CFX (Computational Fluid Dynamic analysis, CFD) and the outcome of the High Heat Flux tests (HHF) made at GLADIS facility. Finally the mechanical behavior of the mock-ups has been compared in terms of ratchetting applying dedicated criteria of the ITER SDC-IC and the fatigue lifetime has been estimated by means of Low Cycle Fatigue Curves (LCFC).