Design and nuclear analysis of the equatorial launcher for EC heating and current drive of ITER plasma

Takahashi, Koji; Abe, Ganji; Isozaki, Masami; Oda, Yasuhisa; Sakamoto, Keishi; Kobayashi, Noriyuki*; Iida, Hiromasa*; Abe, Teruo*; Komatsuzaki, Manabu*

An ITER equatorial EC launcher has been designed to inject a 170GHz, 20MW millimeter (mm) wave beam to plasma with poloidal steering functionality in order to obtain more driven current at the peripheral region of plasma. The equatorial launcher has three sets of mm-wave beam row and each is composed of eight waveguide lines and a quasi-optical transmission region that is formed by a steering and fixed mirror, locating in front of the waveguide outlet. The millimeter wave design to accomplish the high transmission efficiency more than 99% and to compliant with the requirement (criteria) on heat load on the mirrors and beam size at the resonance location of plasma has been successfully developed. This optimized configuration of the millimeter wave components ensures that both mm-wave beams from the middle and bottom row pass through the same BSM opening and then, the feasible and reliable design of BSMs can be carried out. The nuclear analysis of this design modification shows that the residual dose rate at the launcher back end is reduced by 20%, compared to the previous design, which has three openings. This paper reports that the design optimization of the mm-wave design of the equatorial launcher with poloidal beam scan functionality, enhancing the off axis current drive is developed and ensures the effective mm-wave propagation, feasible design of the EL BSMs and nuclear shield structure. The design of the associated structural components such as the port plug and internal shield is also reported.