Recent activities on the study of mm-wave transmission for the ITER equatorial launcher and transmission line

ITER水平ランチャー・伝送系におけるミリ波伝送の研究現状

高橋 幸司; 梶原 健; 小田 靖久; 小林 則幸*; 大島 克己; 坂本 慶司

Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Kobayashi, Noriyuki*; Oshima, Katsumi; Sakamoto, Keishi

水平ランチャーの中性子遮蔽性を高めるための設計変更を検討した結果、ミラー位置の変更で遮蔽性を高めることができるとともに、高周波伝送性能が低下しない設計を見いだした。また、ランチャー用ダイアモンド窓プロトタイプを製作し、大電力伝送実験を行った。0.74MW/100秒,0.52MW/172秒といった伝送に成功するとともに、これまでの半分以下の誘電損失特性を示すことを明らかにした。伝送系については、大電力伝送時に伝送系、特にマイターベンド付近の温度が上昇し、その結果、系全体が11.5mm変形し、それにより基本波のHE11モード純度が10%ほど低下することが判明した。その低下を最小限にするためには、伝送系の効果的な冷却方法や固定方法を検討する必要がある。

The mm-wave design of the EL to improve the shielding capability has been investigated and the modification of the mirror position is essential to obtain the effective shielding without degrading the mm-wave transmission capability. The torus diamond window prototype was manufactured and tested. The transmission of 0.74MW/100sec and of 0.52MW/172sec were demonstrated. Loss tangent of 5.54 10, which was the lowest value that had ever obtained, was measured. The characteristic temperature increase of the waveguides near and between the miter bends has been measured due to high order modes propagation or/and their modes trapping in the transmission line. The measurement shows that the HE11 mode purity was degraded by 10% and on the other hand, the mode content of LP11 mode was increased by 10% when the displacement of waveguides was 11.5mm. This result suggests that the effective cooling of the waveguide or the stiffness support structure for the transmission line component like the miter bend should be considered to minimize the degradation of HE11 mode purity.