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Knaster, J.*; Garin, P.*; Matsumoto, Hiroshi*; Okumura, Yoshikazu*; Sugimoto, Masayoshi*; Arbeiter, F.*; Cara, P.*; Chel, S.*; Facco, A.*; Favuzza, P.*; et al.
Nuclear Fusion, 57(10), p.102016_1 - 102016_25, 2017/06
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.
Okumura, Yoshikazu; Gobin, R.*; Knaster, J.*; Heidinger, R.*; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; et al.
Review of Scientific Instruments, 87(2), p.02A739_1 - 02A739_3, 2016/02
Times Cited Count：9 Percentile：37.96(Instruments & Instrumentation)IFMIF is an accelerator based neutron facility having two set of linear accelerators each producing 125mA/CW deuterium ion beams (250mA in total) at 40MeV. The LIPAc (Linear IFMIF Prototype Accelerator) being developed in the IFMIF-EVEDA project consists of an injector, a RFQ accelerator, and a part of superconducting Linac, whose target is to demonstrate 125mA/CW deuterium ion beam acceleration up to 9MeV. The injector has been developed in CEA Saclay and already demonstrated 140mA/100keV deuterium beam. The injector was disassembled and delivered to the International Fusion Energy Research Center (IFERC) in Rokkasho, Japan, and the commissioning has started after its reassembly 2014; the first beam production has been achieved in November 2014. Up to now, 100keV/120mA/CW hydrogen ion beam has been produced with a low beam emittance of 0.2 
.mm.mrad (rms, normalized).
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
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
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.
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
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.
Okumura, Yoshikazu; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; Gobin, R.*; Harrault, F.*; Heidinger, R.*; et al.
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.203 - 205, 2015/09
Under the framework of Broader Approach (BA) agreement between Japan and Euratom, IFMIF/EVEDA project was launched in 2007 to validate the key technologies to realize IFMIF. The most crucial technology to realize IFMIF is two set of linear accelerator each producing 125mA/CW deuterium ion beams up to 40MeV. The prototype accelerator, whose target is 125mA/CW deuterium ion beam acceleration up to 9MeV, is being developed in International Fusion Research Energy Center (IFERC) in Rokkasho, Japan. The injector developed in CEA Saclay was delivered in Rokkasho in 2014, and is under commissioning. Up to now, 100keV/120mA/CW hydrogen ion beams and 100keV/90mA/CW duty deuterium ion beams are successfully produced with a low beam emittance of 0.21 .mm.mrad (rms, normalized). Delivery of RFQ components will start in 2015, followed by the installation of RF power supplies in 2015.
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：27 Percentile：74.91(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：29.15(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.
Kobayashi, Takayuki; Moriyama, Shinichi; Isayama, Akihiko; Sawahata, Masayuki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.
EPJ Web of Conferences, 87, p.04008_1 - 04008_5, 2015/03
Times Cited Count：6 Percentile：85.05(Physics, Fluids & Plasmas)A dual-frequency gyrotron, which can generate 110 GHz and 138 GHz waves independently, is being developed in JAEA to enable electron cyclotron heating (ECH) and current drive (ECCD) in a wider range of plasma discharge conditions of JT-60SA. Operation for the gyrotron conditioning and parameter optimization toward 1 MW for 100 s, which is the target output power and pulse length for JT-60SA, is in progress without problems. Oscillations of 1 MW for 10 s and 0.51 MW for 198 s were obtained, so far, at both frequencies. In addition, an oscillation (0.3 MW for 20 ms) at 82 GHz was demonstrated as an additional frequency of the dual-frequency gyrotron which shows a possibility of the use of fundamental harmonic wave in JT-60SA.
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
Yokokura, Kenji; Moriyama, Shinichi; Kobayashi, Takayuki; Hiranai, Shinichi; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; Wada, Kenji; Sato, Yoshikatsu; Hoshino, Katsumichi; et al.
JAEA-Technology 2014-002, 64 Pages, 2014/03
JAEA-Technology-2014-002.pdf:6.83MB
A new instrument has been developed to measure spatial distribution of power density and total power of the millimeter wave, by measuring temperature rise of dielectric material inserted in the waveguide. For a measurement, a dielectric disk with thermally insulated support is inserted into the few millimeters gap in the waveguide. The disk is heated by the millimeter wave pulse for 0.10.2 s, and immediately after the pulse, it is pulled up and its temperature distribution is measured by an infrared camera to estimate the spatial power density distribution of the millimeter wave. In the other hand, total transmission power is estimated by the disk temperature reached equilibrium. In the measurement test, deformation of the power density distribution was successfully detected when the mirror angle was intentionally changed in the matching optics unit (MOU) at the waveguide input from the gyrotron. The test result shows that the instrument is effective for both adjustment of MOU without opening the vacuum boundary and to detect any abnormal transmission during operation of the ECH system. The test also shows high reliability of the instrument which stands with 1 MW high power transmission without any arcing or pressure rise in vacuum region. The instrument will be contributed to keep good condition of high power long pulse ECH system by detecting abnormal transmission in the waveguide in operation without open vacuum boundary.
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：27.54(Nuclear Science & Technology)Tobari, Hiroyuki; Inoue, Takashi; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Dairaku, Masayuki; Yamanaka, Haruhiko; Watanabe, Kazuhiro; Sakamoto, Keishi; Kuriyama, Masaaki*; et al.
Fusion Engineering and Design, 88(6-8), p.975 - 979, 2013/10
Times Cited Count：1 Percentile：16.90(Nuclear Science & Technology)The HV bushing, one of the ITER NB components, which is to be procured by JADA, is a multi-conductor feed through composed of five-stage double-layered insulator columns with large brazed ceramic ring and fiber reinforced plastic (FRP) ring. The HV bushing is a bulk head between insulation gas at 0.6 MPa and vacuum. The FRP ring is required to sustain the pressure load, seismic load and dead weight. Brazing area of the ceramic ring with Kovar is required to maintain vacuum leak tightness and pressure tightness against the air filled at 0.6 MPa. To design the HV bushing satisfying the safety factor of 
3.5, mechanical analyses were carried out. As for the FRP ring, it was confirmed that isotropic fiber cloth FRP rings should be used for sufficient strength against shear stress. Also, shape and fixation area of the Kovar sleeve were modified to lower the stress at the joint area. As a result, a design of the insulator for the HV bushing was established satisfying the requirement.
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：16.90(Nuclear Science & Technology)Kariya, Tsuyoshi*; Minami, Ryutaro*; Imai, Tsuyoshi*; Eguchi, Taku*; Sakamoto, Keishi; Mitsunaka, Yoshika*; Numakura, Tomoharu*; Endo, Yoichi*
Plasma and Fusion Research (Internet), 8, p.1205107_1 - 1205107_2, 2013/10
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：29.76(Nuclear Science & Technology)Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.
Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06
Times Cited Count：13 Percentile：46.18(Physics, Fluids & Plasmas)