Qualification Activities for the DTT Divertor

The divertor tokamak test (DTT) facility is currently in the design stage and in the initial phase of construction at the research center ENEA Frascati. The DTT facility aims at searching integrated solutions for the power exhaust issue maintaining plasma performances compatible with future fusion devices. For this reason, the first DTT divertor was designed to accommodate different magnetic configurations: in particular other than single null (SN), the compatibility with X-divertor (XD) and negative triangularity (NT) with different leg lengths was ensured. To accommodate the strike point positions of the different magnetic equilibria, all plasma facing surfaces (i.e., inner and outer vertical targets, as well as the dome) have to be entirely made of tungsten (W) monoblocks. At the same time, to leave more space to the divertor legs, it was decided to design a dome with a flat shape. These two factors along with the armor with W monoblock and the flat shape have required finding ad hoc technological solutions for the plasma facing units (PFUs) of the dome with the need of a research and qualification phase. Above all, a W flat tiles (FTs) design was required at the inner dome end, where the copper cooling pipes turn by 90°. The FT segment covers only a small length of the PFU (40 mm), and the goal is to join both monoblock and FT segments to the pipe in a single manufacturing process. The technique used is the hot radial pressing (HRP), which has been developed in ENEA and qualified for the manufacturing of the ITER inner vertical target.