Preliminary studies and ideas of frequency step-tunable ECRH & CD for DEMO
C. Wu, K. Avramidis, A. Bruschi, T. Franke, G. Granucci, J. Jelonnek, A. Moro, E. Poli, M. Thumm
31st Joint Russian-German Workshop on ECRH and Gyrotrons, 2019, Jun
Electron cyclotron resonance heating and current drive is able to deposit MW power in a localized plasma volume. In ITER, steerable mirrors inside the vacuum vessel (so called front steering) are used to adjust the position of the localized EC wave absorption. To avoid using movable mirrors in a harsh environment close to the plasma, with the so-called remote steering, the movable mirrors are placed at the entrance of the final waveguide. The latter steering method, however, is not easy to be integrated for the engineering and would have a limited range of declination angle. The frequency steering, which involves discrete frequency steps in two to three GHz for a total frequency bandwidth in the order of ± 10 GHz, could also steer the position of the localized current drive. A preliminary study was performed to check the possibility and steering range with the assumed frequency bands for the purpose of NTM stabilization in DEMO. The results will be discussed in this presentation.