Heating & current drive efficiencies, TBR and RAMI considerations for DEMO

The heating & current drive (H&CD) systems in a DEMOnstration fusion power plant are one of the majorenergy consumers. Due to its high demand in electrical energy the H&CD efficiency optimization is animportant goal in the DEMO development.The H&CD power for DEMO, based on physics scenarios for the different plasma phases, is needed forplasma initiation phases (incl. breakdown), current ramp-up, heating to H-mode, burn control, controlledcurrent ramp-down, MHD control and other functions. Plasma control will need significant installedH&CD power, though not continuously used.Previously, in the DEMO1 2015 baseline definitions, optimistic forecasted H&CD efficiencies had beenassumed in the corresponding system code (i.e. PROCESS) module. Realizing that there is a high uncer-tainty in the assumptions the efficiencies have been modified and the impact on the DEMO power plantand basic tokamak configuration are discussed in this article.A comparison of the various H&CD systems NBI (Neutral Beam Injection), Electron Cyclotron (EC), IonCyclotron (IC) in terms of impact on Tritium Breeding Ratio (TBR) due to various openings for the H&CDfront end components in the breeding blanket (BB) is presented.For increasing the reliability as major features the power per system unit and the redundancy areidentified leading to a new proposal for clusters for EC and modular ion-sources for NB.© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).