Divertor Tokamak Testing Facility (DTT): A Test Facility for the Fusion Power Plant

In the European Fusion Roadmap for the realisation of fusion energy within 2050, one of the main mission is the identification of a reliable solution for the heat exhaust in the reactor. Indeed, the power released by the nuclear fusion reactions of deuterium and tritium in the plasma will be in part spread over the so-called blanket that surrounds the plasma, in part, a fifth of the total, will be directed to the so-called divertor. This second flux of energy is constituted primarily by the ashes of the reactions (alpha particles), that would rapidly choke the plasma reactions if not extracted continuously. A "standard" divertor, operating in a plasma fully detached condition, i.e. no contact between plasma and first wall of the vessel, will be tested in ITER. Nonetheless, the baseline strategy implemented in ITER could not be extrapolated to DEMO and future power plants since the amount of fusion power density released in a reactor would exceed the limits available in ITER and a modification of the ITER divertor would be too long and expensive. Then the problem of thermal loads on the divertor may remain particularly critical in the road to the realization of a reactor. For this reason, a dedicated facility, where a number of scaled experiments could be tested, fully integrated with the expected physical parameters and engineering solutions to be used in DEMO, is of paramount importance. DTT, Divertor Tokamk Test facility, has been designed and it is under construction in ENEA Frascati Research Center with the aim to test different divertor magnetic configurations in an integrated way. It will be a high field superconducting tokamak device (6 T) carrying plasma current up to 5.5 MA in pulses with length up to about 100s and with 45 MW of additional heating power, needed to reproduce the energy flux expected in a reactor by the sole fusion reactions in the plasma. To easy the management and the operation of the machine, DTT will indeed operate only with deuterium plasmas. This paper describes the status of the design and construction activities of DTT, highlighting especially the constraints imposed by the divertor system in the integration design activities.