Motivation and context of DTT proposal

DTT parameters

Scientific Exploitation 



Motivation and context of DTT proposal

EUROfusion, the European Consortium for the Development of Fusion Energy, manages the European fusion research activities on behalf of EURATOM. A significant part of the work programme of EUROfusion is devoted to power exhaust issues.

In the General Assembly of October 2017, EUROfusion acknowledged that the DTT proposal may provide important elements for finding solutions to the plasma exhaust problem, a potential crucial issue for DEMO, delivering information in operational ranges or configurations that are not accessible for the present devices or JT-60SA. In the same meeting, the General Assembly approved the principle of involvement of EUROfusion in the DTT facility around 2022-23, within a ceiling of 60 M€. In the General Assembly of April 2018, EUROfusion decided that 60 M€ should be earmarked for DTT in FP9, delaying the decision on the most appropriate involvement of EUROfusion around 2022-2023, when EUROfusion will be able to propose a divertor to be tested or the DTT plant will be at a stage with a low risk to non-completion.

Italy plays a significant role in international nuclear fusion research. Its credibility has been more and more strengthened thanks to coordinated efforts among universities, research institutions and industries, focused on attention to the innovative aspects; this cooperation has resulted in a virtuous circle that can contribute greatly to the development of the nation.

Italian fusion research is carried out under the aegis of MISE (Ministero dello Sviluppo Economico- Ministry of Economic Development) and MIUR (Ministero dell’Istruzione, Università e Ricerca- Ministry of Education, University and Research).

The research institutions that mainly contribute to fusion research are ENEA in Frascati, Consorzio RFX in Padua, Istituto di Fisica del Plasma del CNR in Milan, Consorzio CREATE in Naples, which coordinates the activities of several Universities in Southern Italy (including Università di Napoli Federico II, Università della Campania “L. Vanvitelli”, Università di Cassino and Lazio Meridionale), INFN with its labs in Legnaro, together with the important contributions of a number of other Italian Universities (Politecnici di Torino and Milano, Università di Milano Bicocca, Roma "La Sapienza", Roma "Tor Vergata" e Roma Tre; Cagliari, Catania, Palermo, Pisa and Tuscia). The research groups operating in such institutions have cooperated for many years as part of the EURATOM-ENEA Association and EFDA. Since 2014, the collaboration takes place within the EUROfusion Consortium Agreement.

From the experimental point of view, it is to note the significant results achieved both in Frascati by the FTU Tokamak (born as an upgrade of the FT tokamak, which held the world record of the fusion performance parameter for years, and now is one of the few large facility for liquid lithium plasma facing components) and Padua with RFX-mod (the unique device able to explore, thanks to a sophisticated magnetic feedback system, the Reversed Field Pinch configurations at plasma currents up to 2MA).

Italian researchers also gave a significant contribution to the design and experimental operation of JET in Culham and are significantly contributing, since its starting, to the design and construction of ITER.

Italy is also engaged in the construction, in Padua, of an experimental apparatus, in 1:1 scale, for the injectors of neutrals in ITER. Italian researchers, meanwhile, play a key role in the European "Fusion Road Map", leading several projects (Tasks and Work Packages) in the Horizon 2020 Work programme.

Finally, it should be pointed the high level of integration between national laboratories and the Italian industry, thanks to which a large part of the industrial contracts (around 60%) for the construction of ITER have been auctioned to the Italian companies.

Given the extent and incisiveness of fusion research in Italy and, in addition, taking into account that the removal of heat is one of the most important challenge for the construction of a magnetic confinement fusion reactor, the Italian Government proposed to allocate specific funds for the construction of an experiment dedicated to these problems.

The DTT project has been proposed in 2015 by about one hundred scientists from several Italian institutions (ENEA and its Third Parties), with the support of two EU labs (KIT, Germany; IPPLM, Poland), and the collaboration of scientists from various international labs (including CEA-IRFM, France; CRPP-EFPL, Switzerland; FOM-DIFFER, the Netherlands; IPPLM, Poland). The results were collected in “DTT-Divertor Tokamak Test facility. Project Proposal”, ISBN 978-88-8286-318-0, published in 2015 (DTT “Blue Book”) and in the Special Section: DTT, Fusion Engineering and Design, Vol. 122, 2017; in addition,a new document, the DTT Interim Design Report, i.e. the updated version of the “Blue Book”, will be shortly available.

The relevance of the DTT project is as greater as closer it approaches to parameters and dimensions of DEMO. However, the size and the consequent construction of the project must be, in any case, compatible with the time constraints of the Road Map and the limits of financial resources. This document shows that DTT can achieve its goals with a budget of 500 M€. The project is funded by 60 M€ from EUROfusion, while another 80 M€ will come from the Italian government. The Lazio regional government will supply 25 M€, while China will provide 30 M€ and ENEA partners another 50 M€. The remaining 250 M€ will come from the European Investment Bank via a loan.




DTT parameters

Aim of DTT is to be a reduced size model of DEMO, able to study the problems of the "Scrape Off Layer" (SOL): to this spirit, every design choice has been conformed.

A machine with a plasma major radius of 2.10 m is able to ensure a region of the divertor sufficiently broad to allow the testing of different magnetic configurations and various materials, including metals liquids.

The relatively high toroidal field (BT=6T) will give the possibility to achieve plasma performances (mainly measured by the ratio between power and major radius of about 15 MW/m), not far from those in DEMO.

After the publication of the special issue of Fusion Engineering Design in November 2017 (Vol. 122), the DTT Team has continued its activity to deepen and refine the project, also in the light of some suggestions of EUROfusion, as well as to start the technical and organizational steps toward realization.

The main topics addressed in this review activity include:

  • Site selection: in April 2018 the final decision was to allocate a machine at the ENEA Research Center in Frascati (Rome);
  • Cost revision: in March 2018 a Cost Revision Committee has been appointed to assess the construction costs and give robustness to the economic analysis of the project;
  • Symmetrization: the DTT geometry is now up-down symmetric, so as to allow the introduction of an additional divertor and the realization of double-null configurations;
  • Parameter assessment (see Table): the revision process led to a slight reduction of the major and minor radius (2.10 m and 0.65 m, respectively) and plasma current (5.5 MA) leaving the magnetic field unaltered (6.0 T);
  • Additional review elements: a careful analysis was made taking into nuclear, mechanical, thermal, and MHD issues, leading to a revision of the main components and the various contributions to the additional heating; the maximum DD neutron yield estimated in H-mode high performance operations is 1.0×1017n/s with 1.0×1015n/s DT neutrons (i.e. 1%) from triton burn-up, which makes remote handling needed also in the first phase of operation;
  • Management organization: a legal entity will be founded in 2018 so as to deal with the complex challenges of DTT construction and operation; meanwhile, an Interim Executive Board and an Interim Project Committee have been established for the general management of the project and the coordination of the various activities, respectively;
  • DTT Interim Design Report: an updated version of the “Blue Book” is in preparation and will be shortly available.



Main DTT parameters




R (m)


a (m)




Volume (m3)




Ip (MA)


BT (T)




Pulse length @EOF (s)




Scientific Exploitation

The scientific exploitation of the DTT will be sheared between EUROfusion beneficiaries and international partners. EUROfusion beneficiaries will access the facility through specific calls, issued by the Program Manager Unit, addressing the European fusion program. The remaining experimental time will be devoted to proposals from international partners, duly advertised on the DTT website, and the National programs.

 DTT Exploitation Plan