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Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Times Cited Count：18 Percentile：98.55(Quantum Science & Technology)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.
Schrech, S.*; Aiello, G.*; Meier, A.*; Strauss, D.*; Ikeda, Ryosuke; Oda, Yasuhisa; Sakamoto, Keishi; Takahashi, Koji; Scherer, T.*
Fusion Engineering and Design, 96-97, p.593 - 596, 2015/10
Times Cited Count：11 Percentile：61.29(Nuclear Science & Technology)Takahashi, Koji; Abe, Ganji; Kajiwara, Ken; Oda, Yasuhisa; Isozaki, Masami; Ikeda, Ryosuke; Sakamoto, Keishi; 2 of others*
Fusion Engineering and Design, 96-97, p.602 - 606, 2015/10
Times Cited Count：7 Percentile：45.52(Nuclear Science & Technology)The recent physics analysis reveals that there is the potential to more than double the drive current at the range of 
= 0.4
0.6 if a beam steering direction can be modified from toroidal to poloidal. However, the change of steering direction has a significant impact on the design of the Equatorial EC Launcher (EL), especially, mm-wave propagation and blanket shield modules (BSMs) and a knock-on effect impacting the internal shield structure. The EL has three sets of mm-wave beam row and each is composed of eight waveguide lines and a quasi-optical transmission region that is formed a steering and fixed mirror, locating in front of the waveguide outlet. It has been successfully performed that the outstanding configuration of the mirrors is developed, the mirror actuator is changed from the push-pull to pneumatic concept and the modification of the internal shield structure is minimized as much as possible. This creative modification ensures that both mm-wave beams from the middle and bottom row pass through the same BSM opening and then, the feasible and reliable design of BSMs can be carried out. The nuclear analysis of this design modification shows that the residual dose rate at the launcher back end is reduced by 20%. This paper summarizes that the possible solution of the mm-wave design modification enhancing the off axis current drive functionality is developed and ensures the effective mm-wave propagation, feasible design of the EL BSMs and nuclear shield structure.
Omori, Toshimichi*; Albajar, F.*; Bonicelli, T.*; Darbos, C.*; Denisov, G.*; Gassmanna, T.*; Hanson, G.*; Kajiwara, Ken; Oda, Yasuhisa; Purohit, D.*; et al.
Fusion Engineering and Design, 96-97, p.547 - 552, 2015/10
Times Cited Count：13 Percentile：67.64(Nuclear Science & Technology)An electron cyclotron (EC) system is one of four auxiliary plasma heating systems to be installed in ITER tokamak. The ITER EC system consists of 24 gyrotrons (RFPS: RF power source) with associated 12 high voltage power supplies (HVPSs), a set of evacuated transmission lines (TLs) and two types of launchers. The whole system is designed compatible with propagation of 170 GHz of up to 20 MW microwave power into the plasma. The primary functions of the system include plasma start-up, central heating and current drive (H&CD) and magneto-hydrodynamic (MHD) instabilities control. The design takes present day technology and extends toward high power CW operation, which represents a large step forward as compared to the present state of the art. The ITER EC system will be a stepping stone to future EC systems for DEMO and beyond. The EC system is faced with significant challenges, which not only includes an advanced microwave system for plasma heating and current drive applications but also has to comply with stringent requirements associated with nuclear safety as ITER became the first fusion device licensed as basic nuclear installations as of 9 November 2012. Since conceptual design of the EC system established in 2007, the EC system has progressed to a preliminary design stage in 2012, and is now moving forward toward a final design. The majority of the subsystems are getting to knuckle down the detailed design to realize the future advancement envisioned toward the final design completion.
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：28 Percentile：74.44(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：28.85(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.
Takahashi, Koji; Abe, Ganji; Isozaki, Masami; Oda, Yasuhisa; Sakamoto, Keishi; Kobayashi, Noriyuki*; Iida, Hiromasa*; Abe, Teruo*; Komatsuzaki, Manabu*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05
An ITER equatorial EC launcher has been designed to inject a 170GHz, 20MW millimeter (mm) wave beam to plasma with poloidal steering functionality in order to obtain more driven current at the peripheral region of plasma. The equatorial launcher has three sets of mm-wave beam row and each is composed of eight waveguide lines and a quasi-optical transmission region that is formed by a steering and fixed mirror, locating in front of the waveguide outlet. The millimeter wave design to accomplish the high transmission efficiency more than 99% and to compliant with the requirement (criteria) on heat load on the mirrors and beam size at the resonance location of plasma has been successfully developed. This optimized configuration of the millimeter wave components ensures that both mm-wave beams from the middle and bottom row pass through the same BSM opening and then, the feasible and reliable design of BSMs can be carried out. The nuclear analysis of this design modification shows that the residual dose rate at the launcher back end is reduced by 20%, compared to the previous design, which has three openings. This paper reports that the design optimization of the mm-wave design of the equatorial launcher with poloidal beam scan functionality, enhancing the off axis current drive is developed and ensures the effective mm-wave propagation, feasible design of the EL BSMs and nuclear shield structure. The design of the associated structural components such as the port plug and internal shield is also reported.
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
Oda, Yasuhisa; Fukumoto, Masakatsu; Uto, Hiroyasu
Purazuma, Kaku Yugo Gakkai-Shi, 90(6), P. 356, 2014/06
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：27.24(Nuclear Science & Technology)Saigusa, Mikio*; Atsumi, Kohei*; Yamaguchi, Tomoki*; Oda, Yasuhisa; Sakamoto, Keishi
Fusion Engineering and Design, 88(6-8), p.964 - 969, 2013/10
Times Cited Count：2 Percentile：16.78(Nuclear Science & Technology)Jeong, J. H.*; Bae, Y. S.*; Joung, M.*; Kim, H. J.*; Park, S. I.*; Han, W. S.*; Kim, J. S.*; Yang, H. L.*; Kwak, J. G.*; Sakamoto, Keishi; et al.
Fusion Engineering and Design, 88(5), p.380 - 387, 2013/06
Times Cited Count：4 Percentile：29.49(Nuclear Science & Technology)Atsumi, Kohei*; Yamaguchi, Tomoki*; Nagashima, Koji*; Saigusa, Mikio*; Fukunari, Masafumi*; Oda, Yasuhisa; Sakamoto, Keishi
Plasma and Fusion Research (Internet), 8(Sp.1), p.2405077_1 - 2405077_4, 2013/06
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：16.78(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：19 Percentile：59.66(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：9 Percentile：53.36(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：7 Percentile：32.12(Instruments & Instrumentation)