Conceptual study of ECH/ECCD system for fusion DEMO plant

The conceptual study of the electron cyclotron heating and current drive (ECH/ECCD) system for a DEMO reactor was carried out. The ECH/ECCD system was considered on the basis of a design of the DEMO reactor by JAERI. The reactor is a low aspect ratio tokamak, and its size and magnetic field are similar to those of ITER. Therefore, many ECH/ECCD technologies developed at 170 GHz for ITER can be applied. Truly continuous operation is needed for DEMO, and the neutron fluence from the plasma is two orders of magnitude higher than that of ITER. An RF launcher that has reliability under the condition of high neutron fluence is, critically, important. For power deposition control in the plasma, a gyrotron frequency tuning system is considered as the primary candidate to realize a simple and robust launching system, but two RF beam steering systems are discussed as alternatives.