Dual frequency gyrotron development for JT-60SA

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; Hoshino, Katsumichi; Kajiwara, Ken; Sakamoto, Keishi; Moriyama, Shinichi

A new dual frequency (110 GHz and 138 GHz) gyrotron development began for JT-60SA. An output power and efficiency higher than 1 MW and 30% with a peak heat load lower than 1.4 kW/cm were obtained for both frequencies in calculation. High mode conversion efficiencies of the quasioptical mode converter (96.8% for 110 GHz and 98.3% for 138 GHz), which is higher than the previously developed 110 GHz long pulse gyrotron (96.5%), was obtained. The new gyrotron was fabricated and conditioning operation has been started from the middle of June 2012. The gyrotron output power of approximately 200 kW was obtained, so far, as we expected in the design of the gyrotron at low beam current of 10 A and low beam voltage of 75 kV.