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Oishi, Kazuki*; Igarashi, Daisuke*; Tatara, Ryoichi*; Kawamura, Yukihiko*; Hiroi, Kosuke; Suzuki, Junichi*; Umegaki, Izumi*; Nishimura, Shoichiro*; Koda, Akihiro*; Komaba, Shinichi*; et al.
Journal of Physics; Conference Series, 2462, p.012048_1 - 012048_5, 2023/03
Times Cited Count：0 Percentile：0.21(Physics, Applied)
He spin filter at a pulsed neutron sourceOkudaira, Takuya; Ueda, Yuki; Hiroi, Kosuke; Motokawa, Ryuhei; Inamura, Yasuhiro; Takata, Shinichi; Oku, Takayuki; Suzuki, Junichi*; Takahashi, Shingo*; Endo, Hitoshi*; et al.
Journal of Applied Crystallography, 54(2), p.548 - 556, 2021/04
Times Cited Count：3 Percentile：43.61(Chemistry, Multidisciplinary)Neutron polarization analysis (NPA) for small-angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a He spin filter as a spin analyzer for the scattered neutrons. The He spin filter covers a sufficient solid angle for performing SANS experiments, and the relaxation time of the He polarization is sufficient for continuous use over a few days, thus reaching the typical duration required for a complete set of SANS experiments. Although accurate evaluation of the incoherent neutron scattering, which is predominantly attributable to hydrogen atoms in samples, is practically difficult using calculations based on the sample elemental composition, the developed NPA approach with consideration of the influence of multiple neutron scattering enabled reliable decomposition of the SANS intensity distribution into the coherent and incoherent scattering components. To date, NPA has not been well established as a standard technique for SANS experiments at pulsed neutron sources. This work is anticipated to greatly contribute to the accurate determination of the coherent neutron scattering component for scatterers in various types of organic sample systems in SANS experiments at J-PARC.
Miura, Daisuke*; Kumada, Takayuki; Sekine, Yurina; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Ohara, Takashi; Takata, Shinichi; Hiroi, Kosuke; Morikawa, Toshiaki*; et al.
Journal of Applied Crystallography, 54(2), p.454 - 460, 2021/04
Times Cited Count：1 Percentile：16.63(Chemistry, Multidisciplinary)We developed a spin-contrast-variation neutron powder diffractometry technique that extracts the structure factor of hydrogen atoms, namely, the contribution of hydrogen atoms to a crystal structure factor. Crystals of L-glutamic acid were dispersed in a dpolystyrene matrix containing 4-methacryloyloxy-2,2,6,6,-tetramethyl-1-piperidinyloxy (TEMPO methacrylate) to polarize their proton spins dynamically. The intensities of the diffraction peaks of the sample changed according to the proton polarization, and the structure factor of the hydrogen atoms was extracted from the proton-polarization dependent intensities. This technique is expected to enable analyses of the structures of hydrogen-containing materials that are difficult to determine with conventional powder diffractometry.
Nemoto, Fumiya*; Kofu, Maiko; Nagao, Michihiro*; Oishi, Kazuki*; Takata, Shinichi; Suzuki, Junichi*; Yamada, Takeshi*; Shibata, Kaoru; Ueki, Takeshi*; Kitazawa, Yuzo*; et al.
Journal of Chemical Physics, 149(5), p.054502_1 - 054502_11, 2018/08
Times Cited Count：19 Percentile：70.85(Chemistry, Physical)
test plantYan, X.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu*; Horii, Shoichi*; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.
Nuclear Engineering and Design, 329, p.223 - 233, 2018/04
Times Cited Count：20 Percentile：89.78(Nuclear Science & Technology)The pre-licensing design of an HTGR cogeneration test plant to be coupled to JAEA's existing test reactor HTTR is presented. The plant is designed to demonstrate the system of JAEA commercial plant design GTHTR300C. With construction planned to be completed around 2025, the test plant is expected to be the first-of-a-kind nuclear system operating on two of the advanced energy conversion systems attractive for the HTGR closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.
Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.
Oba, Yojiro*; Morooka, Satoshi; Oishi, Kazuki*; Suzuki, Junichi*; Takata, Shinichi; Sato, Nobuhiro*; Inoue, Rintaro*; Tsuchiyama, Toshihiro*; Gilbert, E. P.*; Sugiyama, Masaaki*
Journal of Applied Crystallography, 50(2), p.334 - 339, 2017/04
Times Cited Count：3 Percentile：29.04(Chemistry, Multidisciplinary)Noda, Yohei*; Koizumi, Satoshi*; Masui, Tomomi*; Mashita, Ryo*; Kishimoto, Hiromichi*; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shinichi; Oishi, Kazuki*; Suzuki, Junichi*
Journal of Applied Crystallography, 49(6), p.2036 - 2045, 2016/12
Times Cited Count：19 Percentile：78.21(Chemistry, Multidisciplinary) test plant; System designYan, X.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu; Horii, Shoichi; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.
Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.827 - 836, 2016/11
Pre-licensing basic design for a cogenerating HTGR test plant system is presented. The plant to be coupled to existing 30 MWt 950
C test reactor HTTR is intended as a system technology demonstrator for GTHTR300C plant design. More specifically the test plant of HTTR-GT/H aims to (1)demonstrate the licensability of the GTHTR300C for electricity production by gas turbine and hydrogen cogeneration by thermochemical process and (2) confirm the operation control and safety of such cogeneration system. With construction and operation completion by 2025, the test plant is expected to be the first of a kind HTGR-powered cogeneration plant operating on the two advanced energy conversion systems of closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Suzuki, Sadaaki; Hiranai, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; et al.
Fusion Engineering and Design, 88(6-8), p.935 - 939, 2013/10
Times Cited Count：4 Percentile：32.11(Nuclear Science & Technology)An antenna having a first mirror driven in the linear motion (LM) and a fixed second mirror was proposed for electron cyclotron range of frequency (ECRF) heating and current drive system, to minimize the risk of cooling-water-leakage. Basic mechanical feasibilities of the bellows covering the movable structures of the antenna were previously investigated using a mock-up. This time, a support structure of the shaft has been designed using a metallic sliding bearing with solid lubricant. The sliding bearing can support combination of linear and rotational motions while a ball bearing supports either linear or rotational motion. We have newly installed the sliding bearing into the mock-up. A vacuum pumping test has been carried out paying attention to the influence of the solid lubricant by mass analysis. To design the LM antenna for JT-60SA in detail, heating and current drive characteristics for typical experimental scenarios of JT-60SA has been investigated by calculation.
Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.
Fusion Science and Technology, 63(1T), p.160 - 163, 2013/05
Times Cited Count：7 Percentile：48.84(Nuclear Science & Technology)A dual frequency electron cyclotron range of frequency system has been developed for JT-60SA, by which a second frequency (135 
140 GHz) is generated in addition to the first frequency of 110 GHz. A development of a dual frequency gyrotron is a key to realize the dual frequency system. The second frequency was chosen to be 138 GHz from the above frequency range from the viewpoint of gyrotron design. In order to realize high-power (
1 MW) and long-pulse operation for both frequencies, we designed main components of the gyrotron (the diamond window, cavity resonator and quasi-optical mode converter). We found the optimum parameter set from the parameters of these components, which has discrete characteristics. It was confirmed that the output power higher than 1 MW is obtained for both frequencies as a result of numerical design. Based on the above design, a dual frequency gyrotron was newly fabricated. In the conditioning operation, an output power was obtained as we expected.
Arai, Masatoshi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki; Suzuki, Junichi*; Takata, Shinichi; Yamada, Takeshi*; et al.
Journal of the Physical Society of Japan, 82(Suppl.A), p.SA024_1 - SA024_14, 2013/01
Times Cited Count：7 Percentile：47.25(Physics, Multidisciplinary)The paper describes developments of neutron scattering instruments in J-PARC neutron facility, which is a short pulse spallation source operated at a repetition rate 25 Hz and has a proton power 1 MW. New concept has been adopted to utilize high intensity coupled moderator even for a high resolution inelastic scattering instruments by taking a pulse shaping chopper system. Advanced technique has been also realized by taking an ability of event-recording system altogether with an improvement of a chopper system, realizing multi-Ei method. The paper also touches upon a general design concept for diffractometers in accordance with the source characteristics.
Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Sato, Yoshikatsu; Hinata, Jun; Yokokura, Kenji; et al.
Proceedings of 37th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2012) (USB Flash Drive), 2 Pages, 2012/09
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.
Ishikawa, Nobuyuki; Chikazawa, Yoshitaka; Fujita, Kaoru; Yamada, Yumi*; Okazaki, Hitoshi*; Suzuki, Shinichi*
Proceedings of 2012 International Congress on Advances in Nuclear Power Plants (ICAPP '12) (CD-ROM), p.483 - 489, 2012/06
The development of safety protection system for JSFR is progressed in terms of logic circuits, selection of trip signals and its setting values for reactor trip. In addition, it is necessitated to evaluate the satisfaction for requirements of the safety protection system by safety analyses considering comprehensive parameter ranges. For this purpose, we will report the current status of the development focusing on the evaluation results for satisfaction of safety protection system based on safety standard.
Isayama, Akihiko; Kobayashi, Takayuki; Yokokura, Kenji; Shimono, Mitsugu; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Wada, Kenji; Hinata, Jun; et al.
Plasma and Fusion Research (Internet), 7(Sp.1), p.2405029_1 - 2405029_5, 2012/05
no abstracts in English
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：44.02(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.
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：62.10(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.
Shinohara, Takenao; Sakai, Kenji; Oi, Motoki; Kai, Tetsuya; Harada, Masahide; Oikawa, Kenichi; Maekawa, Fujio; Suzuki, Junichi; Oku, Takayuki; Takata, Shinichi; et al.
Nuclear Instruments and Methods in Physics Research A, 651(1), p.121 - 125, 2011/09
Times Cited Count：27 Percentile：87.80(Instruments & Instrumentation)no abstracts in English
Hiranai, Shinichi; Suzuki, Sadaaki; Sato, Fumiaki; Kobayashi, Takayuki; Hasegawa, Koichi; Yokokura, Kenji; Moriyama, Shinichi
JAEA-Technology 2010-031, 24 Pages, 2010/09
JAEA-Technology-2010-031.pdf:1.71MB
The JT-60U electron cyclotron heating (ECH) system injects a millimeter wave at 110 GHz into the JT-60U plasma, and heats the plasma or drives a current locally to enhance the confinement performance of the JT-60U plasma. The ECH system of high power gyrotrons, transmission lines and antenna that launch millimeter wave beams toward the plasma. On the long pulse injection, one of the most important purposes is to prevent arcing in the transmission lines and to transmit millimeter wave beams efficiently. This report describes the problems occurred in a long pulse injection test (0.5 MW, 30 s), e.g., increase in released gas, temperature rise of the transmission line and an arcing at the vacuum window during the conditioning process. It also describes measures for the problems, e.g., improvements in vacuum pumping system, cooling system, and arc detector and introduction of the new dummy road system.
Kobayashi, Takayuki; Isayama, Akihiko; Fasel, D.*; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; et al.
Journal of Plasma and Fusion Research SERIES, Vol.9, p.363 - 368, 2010/08
Improvements are required for expanding the pulse length of the JT-60 ECRF system (5s) for JT-60SA (100s). Newly developed power supplies will be fabricated and installed by EU. The conditioning operation of an improved gyrotron equipping a newly designed mode convertor has been started. The mode convertor will reduce heat flux on the internal components and therefore expected to enable long pulse operation at 1 MW. Pre-programmed and/or feedback control of the heater current and anode voltage, which was successfully demonstrated in JT-60U, will be key techniques because the beam current decreases during a shot. The evacuated transmission lines have a capability of 1 MW per line. Since maintenance of the components in the vacuum vessel is difficult, a linear motion antenna concept was proposed to reduce risks of water leakage and fault of the driving mechanism in the vacuum vessel. The detailed design and the low power test of a mock-up antenna have been started.
