The Additional Heating Systems of DTT addressing issues for DEMO HCD Systems

The Divertor Tokamak Test (DTT) facility (6T, 5.5 MA), the construction of which is in the start-up phase, aims to study a solution for the power exhaust in conditions relevant for DEMO. DTT will reach the needed condition of 15 MW/m power flow to the divertor by coupling up to 45 MW of additional power to the plasma. The Additional Heating Systems to achieve this goal are Electron Cyclotron Heating (ECH), Ion Cyclotron Heating (ICH) and Neutral Beam Injector (NBI). The total power of these three systems has a relevant fraction of direct electron heating with up to 32 MW foreseen for ECH. This system, based on existing and assessed technology, has been designed in a modular way, with an architecture and an evacuated multibeam quasi optical transmission line anticipating the issues foreseen in DEMO: compactness, high reliability and MW level of power handling. With the presently available gyrotron unit power of 1 MW 170 GHz, ideally up to 32 gyrotrons installed and simultaneously operated at DTT, approaching DEMO-like relevance and complexity. The ICH system (8 MW of installed power) is designed taking in account the lessons learned from AUG and DEMO about the design of a balanced antenna, with particular attention to the application of the novelties from solid state technology for power generation. The DTT-NBI will be used also to consolidate the design of the DEMO NBI system to be based on similar technology and design solutions. The DTT-NBI will be based on a Radio Frequency plasma source to produce a negative ion current of 40A to be accelerated to 510 keV for an injected power of 10 MW. The main characteristics of DTT heating systems will be presented and discussed, focusing on the aspects helping in the development of the design of DEMO HCD systems.