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Kobayashi, Takayuki; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Ikeda, Ryosuke; Oda, Yasuhisa; Wada, Kenji; Hinata, Jun; Yokokura, Kenji; Hoshino, Katsumichi; et al.
Proceedings of 40th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2015) (USB Flash Drive), 3 Pages, 2015/08
A gyrotron for electron cyclotron heating and current drive (ECH/CD) has been developed for JT-60SA (Super-Advanced). In high-power, long-pulse operations, oscillations of 1 MW/100 s have been demonstrated at both 110 GHz and 138 GHz, for the first time. These results fully satisfied the requirements for JT-60SA. Moreover, it was experimentally shown that the higher power operation at each frequency is expected to be acceptable for this gyrotron from the viewpoint of heat load at the cavity resonator, collector, and stray radiation absorbers. An oscillation at 82 GHz, which is an additional frequency, has been demonstrated up to 2 s at the output power of 0.4 MW, so far. High power experiments toward higher power of 1.5 MW (110/138 GHz) and 1 MW (82 GHz) are ongoing.
Tsubouchi, Masaaki; Nagashima, Keisuke; Yoshida, Fumiko; Ochi, Yoshihiro; Maruyama, Momoko
no journal, ,
A novel design for a contact grating device with an incorporated Fabry-Perot resonator is proposed for high-power terahertz light (THz) generation. We deposited a multilayer consisting of Ta
O
and AlO
on a magnesium-doped stoichiometric LiNbO substrate and fabricated grating grooves on the outermost layer. The multilayer was designed such that conditions for a Fabry-Perot resonator were satisfied for light diffracted by the grating. Consequently, the diffraction efficiency was enhanced by the resonator. The diffraction efficiency of the fabricated device was 71%. THz light generation was also demonstrated with the contact grating device.
Kono, Nanase; Itakura, Ryuji; Tsubouchi, Masaaki
no journal, ,
We realize a relativistic Doppler reflection of THz light from a counter-propagating plasma mirror in silicon (Si), and demonstrate a frequency up-shift of the reflected THz light using a practically simple method, which allows us to apply the up-shift to the THz optics. The average frequency of the reflected THz light is 1.4 times higher than that of an input THz light. The frequency up-shift is achieved by a low pump energy density (2 
J mm
) for generating the plasma mirror, which is suitable for the application.