Prototype development of the ITER EC system with 170 GHz gyrotron

170GHzジャイロトロンを用いたITER ECシステムのプロトタイプ開発

小田 靖久; 梶原 健; 池田 亮介; 大島 克己; 林 一生*; 高橋 幸司; 坂本 慶司; Purohit, D.*; Gandini, F.*; 大森 俊道*; Darbos, C.*; Henderson, M.*

Oda, Yasuhisa; Kajiwara, Ken; Ikeda, Ryosuke; Oshima, Katsumi; Hayashi, Kazuo*; Takahashi, Koji; Sakamoto, Keishi; Purohit, D.*; Gandini, F.*; Omori, Toshimichi*; Darbos, C.*; Henderson, M.*

To study the operational performance of ITER EC heating and current drive system (H&CD), a mock-up of the ITER mm wave system has been assembled using the high power long gyrotron test stand in JAEA. The prototype system is composed of the primary parts of the EC H&CD system, including: 170 GHz gyrotron, power supply, transmission line (TL) and mock-up of equatorial launcher (EL) and control system. The JAEA test stand is a flexible system with its center piece a frequency-step-tunable gyrotron at 170 GHz/137 GHz/104 GHz. The output beam is radiated to the identical direction from the output window for each frequency, consequently the power was transmitted to the end of the TL at these three frequencies. The system has achieved CW 5 kHz power switching, which demonstrates the compatibility for MHD control of ITER plasma. The modulation was achieved using a novel configuration of the electron beam acceleration power supply. In the experiment, stable 5 kHz of power modulation was demonstrated with minimized spurious frequency excitation at the ramp-up phase of each pulse which satisfied the ITER criteria.