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Hashimoto, Shunsuke*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Shibata, Kaoru; Yamada, Takeshi*
Journal of Molecular Liquids, 342, p.117580_1 - 117580_8, 2021/11
Times Cited Count：3 Percentile：25.84(Chemistry, Physical)Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFGNMR) analyses of a nanofluid composed of silicon dioxide (SiO
) nanoparticles and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. The obtained experimental results indicate that SiO particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO nanofluids.
Okuno, Kiyoshi; Nakajima, Hideo; Koizumi, Norikiyo
IEEE Transactions on Applied Superconductivity, 16(2), p.880 - 885, 2006/06
Times Cited Count：11 Percentile：51.46(Engineering, Electrical & Electronic)no abstracts in English
Mori, Masahiro; ITER Japanese Participant Team
Fusion Engineering and Design, 81(1-7), p.69 - 77, 2006/02
Times Cited Count：1 Percentile：9.94(Nuclear Science & Technology)The ITER Transitional Arrangements (ITA) are conducted by the International Team with supports from participant teams (PTs). The Japanese PT (JA-PT) set up in JAERI has contributed to ITA by sharing a lot of technical tasks to verify feasibilities of fabrication and quality control method in procuring ITER equipments and facilities. For examples, trial fabrications of Nb3Sn strands have been performed by JA-PT with four potential suppliers, and one of the strand which meet the ITER requirements in all key parameters have already been chosen for one of the suppliers. All strands including the other suppliers strands will be fully qualified by the end of 2005. The trial fabrications of CS jackets and material for TF coil structure are also in progress at industrial level. Fabrication of the partial mock-ups of the vacuum vessel is also ongoing. Furthermore, JA-PT has made several technical developments on NB and EC systems to improve reliability of long pulse operations. Completing these technical preparations will make it possible to finalize the specification of ITER procurements.
Nishimura, Arata*; Muroga, Takeo*; Takeuchi, Takao*; Nishitani, Takeo; Morioka, Atsuhiko
Fusion Engineering and Design, 81(8-14), p.1675 - 1681, 2006/02
Times Cited Count：3 Percentile：24.08(Nuclear Science & Technology)In a fusion reactor plant, a neutral beam injector (NBI) will be operated for a long time, and it will allow neutron streaming from NBI ports to outside of the plasma vacuum vessel. It requires the superconducting magnet to develop nuclear technology to produce stable magnetic field and to reduce activation of the magnet components. In this report, the back ground of the necessity and the contents of the nuclear technology of the superconducting magnets for fusion application are discussed and some typical investigation results are presented, which are the neutron irradiation effect on Nb
Sn wire, the development of low activation superconducting wire, and the design concept to reduce nuclear heating and nuclear transformation by streaming. In addition, recent activities in high energy particle physics are introduced and potential ripple effect of the technology of the superconducting magnets is described briefly.
Hemsworth, R. S.*; Inoue, Takashi
IEEE Transactions on Plasma Science, 33(6), p.1799 - 1813, 2005/12
Times Cited Count：96 Percentile：92.88(Physics, Fluids & Plasmas)The positive or negative ion sources which form the primary components of neutral beam injection systems used in magnetic fusion have to meet simultaneously several demanding requirements. This paper describes the underlying physics of modern positive ion sources, which provide the required high proton fraction (
90%) and high current density (
2 kA/m
) at a low source pressure (0.4 Pa) with a high electrical efficiency and uniformity across the accelerator grids. The development of negative ion sources, which are required if high energy neutral beams are to be produced, is explained. The paper reports that negative ion sources have achieved many of the parameters required of sources for the neutral beam injectors of future fusion devices and reactors, 200 A/m of D
at low pressure, 
0.3 Pa, with low co-extracted electron content. The development needed to meet all the requiremens of future systems is briefly discussed.
test results of a D-shaped NbAl CICC coil fabricated with a react-and-wind process for the National Centralized TokamakAndo, Toshinari*; Kizu, Kaname; Miura, Yushi*; Tsuchiya, Katsuhiko; Matsukawa, Makoto; Tamai, Hiroshi; Ishida, Shinichi; Koizumi, Norikiyo; Okuno, Kiyoshi
Fusion Engineering and Design, 75-79, p.99 - 103, 2005/11
Times Cited Count：1 Percentile：10.41(Nuclear Science & Technology)no abstracts in English
Ueda, Yoshio*; Inoue, Takashi; Kurihara, Kenichi
Nihon Genshiryoku Gakkai-Shi, 46(12), p.845 - 852, 2004/12
no abstracts in English
Yamamoto, Kazuyoshi; Kumada, Hiroaki; Nakai, Kei*; Endo, Kiyoshi*; Yamamoto, Tetsuya*; Matsumura, Akira*
Proceedings of 11th World Congress on Neutron Capture Therapy (ISNCT-11) (CD-ROM), 14 Pages, 2004/10
A dose distribution considered the tumor cell density distribution is required on the radiation therapy. We propose a novel method of determining target region considering the tumor cell concentration as a new function for the next generation Boron Neutron Capture Therapy (BNCT) dosimetry system. It has not been able to sufficiently define the degree of microscopic diffuse invasion of the tumor cells peripheral to a tumor bulk in malignant glioma using current medical imaging. Referring to treatment protocol of BNCT, the target region surrounding the tumor bulk has been set as the region which expands at the optional distance with usual 2cm margin from the region enhanced on T1 weighted gadolinium Magnetic Resonance Imaging (MRI). In this research, the cell concentration of the region boundary of the target was discussed by using tumor cell diffusion model in the sphere spatio-temporal system. The survival tumor cell density distribution after the BNCT irradiation was predicted by the two regions diffusion model for a virtual brain phantom.
Okuno, Kiyoshi
Chodendo Web 21 (Internet), (2004年8月), P. 1, 2004/08
no abstracts in English
Okuno, Kiyoshi; Shikov, A.*; Koizumi, Norikiyo
Journal of Nuclear Materials, 329-333(Part1), p.141 - 147, 2004/08
Times Cited Count：14 Percentile：66.01(Materials Science, Multidisciplinary)A tokamak fusion reactor requires a superconducting magnet system for plasma confinement and control. Higher magnetic field of the toroidal field (TF) coil can offer better performance of the reactor. Therefore, fusion magnet development always drives a new superconductor to be used in a large magnet on an industrial basis. Magnets for the International Thermonuclear Experimental Reactor (ITER) use NbSn in order to generate a peak magnetic field of 13 T. Technologies for NbSn superconductor has made a significant progress through the extensive development in ITER including the manufacture of the full-scale model coils. A next generation superconductor, NbAl, has outstanding features of large critical current density at the high field. High Tc (Critical Temperature) superconductor (HTS) is another candidate, and if it becomes available, a magnetic filed above 20 T can be realized in fusion reactor. However, technical issues have to be solved for the application of these innovate superconducting materials in Fusion Reactor.
Konovalov, S. V.; Mikhailovskii, A. B.*; Kovalishen, E. A.*; Kamenets, F. F.*; Ozeki, Takahisa; Shirokov, M. S.*; Takizuka, Tomonori; Tsypin, V. S.*
Doklady Physics, 49(7), p.405 - 408, 2004/07
Times Cited Count：1 Percentile：11.77(Mechanics)Effect of feedback system, placed outside the vacuum vessel, on neoclassical tearing modes (NTMs) in tokamaks is analytically studied. External matching parameters for magnetic island chain are derived for the simplest case of step profile of equilibrium parallel current. The structure of dynamical equations for the island width and island rotation frequency in terms of matching parameters is explained. It is shown that such a feedback system can lead to essential shift of the island rotation, in particular, for stabilization of NTMs by the polarization current effect.
Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 14(2), p.1376 - 1381, 2004/06
Times Cited Count：6 Percentile：36.62(Engineering, Electrical & Electronic)Fusion magnets have major features of a large size, high magnetic field and operation under huge electromagnetic forces together with nuclear radiation. From this point of view, new design principles and fabrication concepts were proposed to build the ITER CS, and a model coil programme was performed for verification. The model coil reached its design point of 13 T and 46 kA, achieving all the goals of the development programme, including the following areas: (1) high-performance NbSn strand and mass production of about 26.5 t, (2) high-strength jacket materials (Incoloy 908, titanium, stainless steel) that can undergo NbSn heat treatment, (3) 46 kA cable-in-conduit conductors in a total length of 5 km, (4) insulation materials that can withstand up to 10 MGy radiation dose, (5) fabrication using wind-react-and-transfer method that enables Nb3Sn application to a large magnet with mechanically rigid and high-voltage insulated windings. Results and experiences from the programme are being fed back into the design and QA requirements of the ITER magnets.
Kishimoto, Yasuaki
Purazuma, Kaku Yugo Gakkai-Shi, 79(5), p.460 - 463, 2003/05
This is a collection of review article related to the "Multiple Time and Spatial Scale Plasma Simulation" of various fields including fundamental research area of self-organization, magnetic and laser fusion field, space and astrophysics field where a plasma plays an essential roles.
Koizumi, Norikiyo; Okuno, Kiyoshi
Purazuma, Kaku Yugo Gakkai-Shi, 79(4), p.420 - 421, 2003/03
no abstracts in English
Tsunematsu, Toshihide; Seki, Masahiro; Tsuji, Hiroshi; Okuno, Kiyoshi; Kato, Takashi; Shibanuma, Kiyoshi; Hanada, Masaya; Watanabe, Kazuhiro; Sakamoto, Keishi; Imai, Tsuyoshi; et al.
Fusion Science and Technology, 42(1), p.75 - 93, 2002/07
Times Cited Count：1 Percentile：10.13(Nuclear Science & Technology)Japanese contributions to ITER Engineering Design Activity are presented, together with an introduction of the objectives and design of the ITER whose program have been carried out through the international collaboration by EU, Japan, Russian Federation and the USA. New technologies have been produced through the development, fabrication and testing of scalable models in the fields of superconducting magnet, reactor structure with vacuum vessel, high-heat-flux plasma facing component, neutral beam injector, high-power mm-wave generator and so on. As major contributions from Japan, development and testing results of a 13-T, 640-MJ, NbSn pulsed magnet, a 18-degree sector of vacuum vessel with a height of 15 m and a width of 9 m, CFC armors to CuCrZr cooling tube that withstood 20 MW/m, a 31 mA/cm negative ion beam source, a 1-MeV beam-accelerator, a 1-MW 170-GHz gyrotron were described.
Hamada, Kazuya; Nakajima, Hideo; Okuno, Kiyoshi; Endo, Sakaru*; Kikuchi, Kenichi*; Kubo, Yoshio*; Aoki, Nobuo*; Yamada, Yuichi*; Osaki, Osamu*; Sasaki, Takashi*; et al.
JAERI-Tech 2002-027, 23 Pages, 2002/03
JAERI-Tech-2002-027.pdf:2.94MB
The Engineering Design Activities (EDA) for the International Thermonuclear Experimental Reactor (ITER) was performed under the collaboration of Japan, EU, Russia and the US. The EDA was successfully completed in July 2001, in which the development of fabrication technology for advanced components, such as superconducting coils, was conducted. The ITER magnet system consists of Toroidal Field coils, a Central Solenoid (CS), Poloidal Field coils and Correction coils. The construction of these coils requires advanced technologies that fairly exceeded those available at the start of the EDA. Therefore, CS Model Coil and TF Model Coil projects were implemented. To fabricate the CS Model Coil, the fabrication technologies for high performance strand, large cable, winding, heat treatment, joint and insulation are indispensable. This report describes the above detailed fabrication technologies successfully developed in the CS Model Coil Project.
Okuno, Kiyoshi; Bessette, D.*; Ferrari, M.*; Huguet, M.*; Jong, C.*; Kitamura, Kazunori*; Krivchenkov, Y.*; Mitchell, N.*; Takigami, Hiroyuki*; Yoshida, Kiyoshi; et al.
Fusion Engineering and Design, 58-59, p.153 - 157, 2001/11
Times Cited Count：2 Percentile：19.6(Nuclear Science & Technology)no abstracts in English
Seki, Yasushi; Mori, Seiji*; Nishio, Satoshi; Ueda, Shuzo; Kurihara, Ryoichi
Journal of Nuclear Science and Technology, 37(Suppl.1), p.268 - 275, 2000/03
no abstracts in English
Watanabe, Kazuhiro; Akiba, Masato; Hatano, Toshihisa; Imai, Tsuyoshi; Kuriyama, Masaaki; Ohara, Yoshihiro; Okumura, Yoshikazu; Tsuji, Hiroshi
Proceedings of 10th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion (ITC-10), p.525 - 529, 2000/00
no abstracts in English
Konno, Chikara; Maekawa, Fujio; Oyama, Yukio; Wada, Masayuki*; Ikeda, Yujiro; Maekawa, Hiroshi; Kasugai, Yoshimi; M.Z.Youssef*; A.Kumar*; M.A.Abdou*
Fusion Engineering and Design, 42, p.267 - 273, 1998/00
Times Cited Count：2 Percentile：24.46(Nuclear Science & Technology)no abstracts in English
