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Oshima, Katsumi; Oda, Yasuhisa; Takahashi, Koji; Terakado, Masayuki; Ikeda, Ryosuke; Hayashi, Kazuo*; Moriyama, Shinichi; Kajiwara, Ken; Sakamoto, Keishi
JAEA-Technology 2015-061, 65 Pages, 2016/03
JAEA-Technology-2015-061.pdf:24.28MB
In JAEA, an ITER relevant control system for ITER gyrotron was developed according to Plant Control Design Handbook. This control system was developed based on ITER CODAC Core System and implemented state machine control of gyrotron operation system, sequential timing control of gyrotron oscillation startup, and data acquisition. The operation of ITER 170 GHz gyrotron was demonstrated with ITER relevant power supply configuration. This system is utilized for gyrotron operation test for ITER procurement. This report describes the architecture of gyrotron operation system, its basic and detailed design, and recent operation results.
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.
Kobayashi, Takayuki; Moriyama, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Hoshino, Katsumichi; et al.
Nuclear Fusion, 55(6), p.063008_1 - 063008_8, 2015/06
Times Cited Count：25 Percentile：77.57(Physics, Fluids & Plasmas)A gyrotron enabling high-power, long-pulse oscillations at both 110 GHz and 138 GHz has been developed for electron cyclotron heating (ECH) and current drive (CD) in JT-60SA. Oscillations of 1 MW for 100 s have been demonstrated at both frequencies, for the first time as a gyrotron operating at two frequencies. The optimization of the anode voltage, or the electron pitch factor, using a triode gun was a key to obtain high power and high efficiency at two frequencies. It was also confirmed that the internal losses in the gyrotron were sufficiently low for expected long pulse operation at the higher power level of 
1.5 MW. Another important result is that an oscillation at 82 GHz, which enables to use fundamental harmonic waves in JT-60SA while the other two frequencies are used as second harmonics waves, was demonstrated up to 0.4 MW for 2 s. These results of the gyrotron development significantly contribute to enhancing operation regime of the ECH/CD system in JT-60SA.
Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*
Fusion Science and Technology, 67(4), p.718 - 731, 2015/05
Times Cited Count：4 Percentile：33.25(Nuclear Science & Technology)Development of an electron cyclotron (EC) equatorial launcher has been undergoing a series of prototype tests and design enhancements intending to improve reliability and functionality of the launcher. The design enhancements include adaptation of the launcher steering angles such that one of three beam rows of the launcher is necessary flipped to perform counter current drive (to conform to a new ITER physics requirement). Also the top and bottom steering rows have been tilted with angle of 5
so that the top and bottom beam row can access from on axis to near mid-radius. Furthermore, the position of the focusing mirror that forms a quasi-optical in-vessel millimeter wave transmission line is modified to increase the nuclear shielding capability. High power experiment of the mm-wave launching system mock-up fabricated in basis of the design confirmed the successful steering capability of 2040. It was measured that some of stray RF propagated in the beam duct and generated some heat on the duct at a certain condition of mm-wave transmission. Prototype tests also include the fabrication of the blanket shield module and the partial port plug mock-up and have shown no serious technological issue on the fabrication and the cooling functionality.
Oda, Yasuhisa; Oshima, Katsumi; Nakamoto, Takashi*; Hashimoto, Yasunori*; Yamamoto, Tsuyoshi; Hayashi, Kazuo*; Ikeda, Yukiharu; Ikeda, Ryosuke; Kajiwara, Ken; Takahashi, Koji; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 90(7), p.365 - 373, 2014/07
no abstracts in English
Kajiwara, Ken; Takahashi, Koji; Oda, Yasuhisa; Kobayashi, Noriyuki*; Sakamoto, Keishi
Fusion Engineering and Design, 89(1), p.6 - 10, 2014/01
Times Cited Count：4 Percentile：30.92(Nuclear Science & Technology)Takahashi, Koji; Iida, Hiromasa*; Kobayashi, Noriyuki*; Kajiwara, Ken; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*
Fusion Science and Technology, 63(1T), p.156 - 159, 2013/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Nuclear analysis of the ITER equatorial EC launcher has been carried out to determine heat and/or particle loads on its components and also to evaluate the possibility of "hands-on maintainability" (personnel accessibility) to the launcher back-end. Monte Carlo code "MCNP5" is applied to simulate the radiation leak from fusion plasma to the special region around the launcher. The results indicate a significant radiation leak at the gaps between the port walls and port plug frame and at the waveguide bundles in the launcher. Another significant neutron leakage is through the port wall consisting of only stainless steel but without light isotopes such as water. The shut down dose rates was estimated at the port interspace behind the launcher at the level of the required value of 100 
Sv/h. This analysis offers the potential to modify the launchers shielding layout to minimize the above leakage and further reduce the shut down dose rates in the regions of personnel access.
high power gyrotronKajiwara, Ken; Oda, Yasuhisa; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi
Fusion Science and Technology, 63(1T), p.35 - 39, 2013/05
Times Cited Count：2 Percentile：18.63(Nuclear Science & Technology)Kajiwara, Ken; Sakamoto, Keishi; Oda, Yasuhisa; Hayashi, Kazuo*; Takahashi, Koji; Kasugai, Atsushi
Nuclear Fusion, 53(4), p.043013_1 - 043013_5, 2013/04
Times Cited Count：18 Percentile：62.36(Physics, Fluids & Plasmas)Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Kobayashi, Noriyuki*; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03
The ITER equatorial EC launcher is making a large technology to injecting 
20 M and CW operation. The design of the shield blanket structure that tolerates thermal and electromagnetic load is attained. The port plug structure considering the fabrication process applying HIP and TIG-welding are designed. The mm-wave design that enables to guide the wave power of 20 MW into plasma with toroidal steering capability of 20 40 and efficiency of 98.4 99% assuming HE11 fundamental wave mode + TEM000 gaussian mode are proceeded. Reduction of the heat load to 2.1 MW/m
on the steering mirror are attained. These results allow the transmission of 2.0 MW per a waveguide and the required radiation profile from the launcher. The full scale mock-up of the mm-wave launching system consisting of the waveguides and the mirrors and the subcomponents such as the steering mechanism of the mirror, the cooling water lines and etc., are fabricated to investigate the design availability. High power (0.5 MW) experiment of the mock-up confirmed the expected wave beam propagation and steering capability of 20 40. The mock-up of the shield blanket module and the partial mock-up of the port plug structure are fabricated based on the present design to investigate the manufacturability and the performance of the cooling water flow. The results will reflect back to the fabrication design of the structural components of the equatorial launcher.
Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*
Fusion Engineering and Design, 88(2), p.85 - 93, 2013/02
Times Cited Count：7 Percentile：49.28(Nuclear Science & Technology)The design of the torus diamond window for the ITER electron cyclotron heating and current drive (EC H&CD) system has advanced considering a reliable and manufacturable structure. The diamond window prototype was fabricated in basis of the design and the high power experiment was carried out to verify the millimeter wave transmission capability. Transmission of 740 kW-100 sec was demonstrated and no significant temperature increase of the window structure and no damage on the diamond disk was obtained. The saturation of the cooling water for the window was observed and loss tangent of 7.8 
10
, which was the lowest value that we had ever obtained at JAEA, was evaluated. This result indicates that the diamond window design is feasible and promising the high power more than 1 MW transmission.
Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Mitsunaka, Yoshika*; Sakamoto, Keishi
Review of Scientific Instruments, 84(1), p.013501_1 - 013501_6, 2013/01
Times Cited Count：6 Percentile：30.78(Instruments & Instrumentation)Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Sakamoto, Keishi
Fusion Science and Technology, 61(3), p.203 - 208, 2012/04
Times Cited Count：9 Percentile：56.92(Nuclear Science & Technology)Kajiwara, Ken; Oda, Yasuhisa; Kasugai, Atsushi; Takahashi, Koji; Sakamoto, Keishi
Applied Physics Express, 4(12), p.126001_1 - 126001_3, 2011/12
Times Cited Count：39 Percentile：80.89(Physics, Applied)Kobayashi, Takayuki; Isayama, Akihiko; Hasegawa, Koichi; Suzuki, Sadaaki; Hiranai, Shinichi; Sato, Fumiaki; Wada, Kenji; Yokokura, Kenji; Shimono, Mitsugu; Sawahata, Masayuki; et al.
Fusion Engineering and Design, 86(6-8), p.763 - 767, 2011/10
Times Cited Count：6 Percentile：44.28(Nuclear Science & Technology)Progress of antenna development of the Electron Cyclotron Range of Frequency system for JT-60 SA is presented. Capability of pulse length of 100 s, which requires active cooling for mirrors, and flexibility of beam injection angles in both poloidal and toroidal directions are required for the antenna with high reliability. Mechanical and structural design works of the launcher (antenna and its support with steering structure) based on a linear motion antenna concept are in progress. The key component is a long-stroke bellows which enables to alter poloidal injection angle and a bellows which enables to alter toroidal injection angle. Using a newly fabricated mock-up of the steering structure, it was confirmed that the antenna was mechanically realized for poloidal and toroidal injection angle ranges of -10 to +45 and -15 to +15, respectively. Those angles are consistent with angles required in JT-60SA. The results of thermal and structural analyses are also presented.
Takahashi, Koji; Kajiwara, Ken; Okazaki, Yukio*; Oda, Yasuhisa; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*
Fusion Engineering and Design, 86(6-8), p.982 - 986, 2011/10
Times Cited Count：7 Percentile：48.91(Nuclear Science & Technology)In order to optimize the physics performance of ITER, the millimeter (mm) wave design of the equatorial electron cyclotron launcher is modified so that one-third of the total mm-wave injection power can be flipped to drive plasma current in the counter direction. The design change to perform the poloidal beam tilting of 5 at top and bottom beam row is conducted so that more efficient central power deposition is achievable. The opening shape in the blanket shield module (BSM) structure is also optimized to minimize the degradation of the mm-wave transmission efficiency. The degradation is only 0.3%. The modularization design of the steering mirror components and the internal shield, the application of a rail structure to perform the alignment of the steering mirror installation and the space allocation behind the BSM structure are implemented to increase the reliability, the manufacturability and the maintenability of the launcher design.
Kajiwara, Ken; Oda, Yasuhisa; Kasugai, Atsushi; Takahashi, Koji; Sakamoto, Keishi; Darbos, C.*; Henderson, M. A.*
Fusion Engineering and Design, 86(6-8), p.955 - 958, 2011/10
Times Cited Count：9 Percentile：57.01(Nuclear Science & Technology)Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Sato, Fumiaki; et al.
Nuclear Fusion, 51(10), p.103037_1 - 103037_10, 2011/10
Times Cited Count：19 Percentile：62.41(Physics, Fluids & Plasmas)A new gyrotron operation technique to increase oscillation efficiency was developed on the JT 60 ECRF system. The electron pitch factor was optimized by controlling anode voltage within 0.1 s after the start of the operation. By applying this technique, the gyrotron output power of 1.5 MW for 4 s was recorded, for the first time. The reduced collector heat load at 1.5 MW operations was reduced by 20% and it will be acceptable for longer pulse operation. A new gyrotron with an improved mode converter was developed in order to demonstrate reduction of the stray radiation which had limited the pulse length. The stray radiation was reduced to 1/3 of that of the original gyrotron. A conditioning operation of the improved gyrotron is proceeding up to 31 s at 1 MW. These progresses significantly contribute to enhancing the high power and long pulse capability of the ECRF system toward JT 60SA.
Kobayashi, Takayuki; Moriyama, Shinichi; Isayama, Akihiko; Hoshino, Katsumichi; Sakamoto, Keishi; Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Kasugai, Atsushi
Denki Gakkai Kenkyukai Shiryo, Genshiryoku Kenkyukai (NE-11-6), p.11 - 15, 2011/09
The developments of radio frequency systems for plasma heating and current drive have been continued for magnetically-confined fusion devices, such as JT-60SA, ITER. The specifications of the systems are shown. Recent progress in the electron cyclotron range of frequency system developments, especially for the JT-60SA, is summarized.
Oda, Yasuhisa; Yamaguchi, Toshikazu*; Shiraishi, Yuya*; Komurasaki, Kimiya*; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi
Journal of Infrared, Millimeter, and Terahertz Waves, 32(6), p.877 - 882, 2011/06
Times Cited Count：8 Percentile：44.43(Engineering, Electrical & Electronic)