Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 120

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Three-dimensional modeling for deformation and movement of siltfence in water; Coupled simulation of water flow and siltfence

Yamada, Susumu; Machida, Masahiko; Tanaka, Minori*; Seki, Katsumi*; Arikawa, Taro*

Nippon Oyo Suri Gakkai Rombunshi, 31(1), p.20 - 43, 2021/03

no abstracts in English

Journal Articles

Turbulent transport reduction induced by transition on radial electric field shear and curvature through amplitude and cross-phase in torus plasma

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku*; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*

Scientific Reports (Internet), 7(1), p.14971_1 - 14971_8, 2017/11

 Times Cited Count:15 Percentile:15.52(Multidisciplinary Sciences)

Journal Articles

Experimental identification of electric field excitation mechanisms in a structural transition of tokamak plasmas

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.

Scientific Reports (Internet), 6, p.30720_1 - 30720_7, 2016/08

 Times Cited Count:11 Percentile:29.88(Multidisciplinary Sciences)

In this Letter, we report model verifications for a key physics for the L-H transition. Radial electric field excitation, using discharges having a two-step transition. Examining time derivative of Poissons equation, it is found that the sum of the loss cone loss current and neoclassical bulk viscosity current agrees the experimentally observed current in the order of magnitude at the first transition. Following second transition and an ambipolar condition in the L-mode cannot be explained by the models.

Journal Articles

Experimental fast reactor "JOYO" retrieval for the bent MARICO-2 test subassembly using remote control devices

Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*; Kondo, Katsumi*; Ito, Hideaki; Ashida, Takashi; Nakamura, Toshiyuki

FAPIG, (190), p.3 - 8, 2015/07

no abstracts in English

Journal Articles

Dynamics of edge limit cycle oscillation in the JFT-2M tokamak

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.

Nuclear Fusion, 54(7), p.073017_1 - 073017_14, 2014/07

 Times Cited Count:22 Percentile:18.62(Physics, Fluids & Plasmas)

In the JFT-2M tokamak, limit-cycle oscillation among several variables is observed before L-to-H transition. Spatiotemporal dynamics of the LCO is analyzed in detail. Zonal fows are not seen, and modulation in edge-localized poloidal flow and density gradient is observed. Modulation is also seen in Reynolds stress, caused by that in turbulence intensity and turbulence wavenumber. However, flow acceleration is not able to be explained by the modulation in the Reynolds stress. Rapid inward propagation in density gradient and turbulence packet is also observed. Characteristics of the propagation are veried by means of turbulence spreading theory and diffusion theory.

Journal Articles

Edge radial electric field formation after the L-H transition on JT-60U

Kamiya, Kensaku; Matsunaga, Go; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Kamada, Yutaka; Ida, Katsumi*; Ito, Kimitaka*; JT-60 Team

Contributions to Plasma Physics, 54(4-6), p.591 - 598, 2014/06

 Times Cited Count:6 Percentile:62.98(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Mechanical properties of full austenitic welding joint at cryogenic temperature for the ITER toroidal field coil structure

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.

Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10

 Times Cited Count:8 Percentile:38.69(Nuclear Science & Technology)

ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.

Journal Articles

Spatiotemporal structures of edge limit-cycle oscillation before L-to-H transition in the JFT-2M tokamak

Kobayashi, Tatsuya*; Ito, Kimitaka*; Ido, Takeshi*; Kamiya, Kensaku; Ito, Sanae*; Miura, Yukitoshi; Nagashima, Yoshihiko*; Fujisawa, Akihide*; Inagaki, Shigeru*; Ida, Katsumi*; et al.

Physical Review Letters, 111(3), p.035002_1 - 035002_5, 2013/07

 Times Cited Count:79 Percentile:5.09(Physics, Multidisciplinary)

In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit cycle oscillation that precedes L-to-H transition. Zonal flows are not observed during LCO, and the oscillation is the periodic generations/decays of barrier with edge localized mean flow. Oscillatory Reynolds stress is found too small to accelerate the LCO flow. Changes of the density gradient and turbulence amplitude are found to propagate into the core in a ballistic manner, suggesting a cause of fast change of core transport after H-mode transition.

Journal Articles

Plasma boundary of 3D MHD equilibrium inferred from flow patterns

Ida, Katsumi; Kamiya, Kensaku; Suzuki, Yasuhiro*

Purazuma, Kaku Yugo Gakkai-Shi, 89(5), p.319 - 327, 2013/05

This paper provides and proposes a new technique to determine the location of the LCFS that is based on a characterization of the Er structure derived from CXS measurements in the LHD. We found that the spatial derivative in the Er structure had the local maximum value at the region very near, or possibly outside the vacuum LCFS location of vacuum magnetic field at the outer midplane in the low beta plasma.

Journal Articles

Characterization of edge radial electric field structures in the large helical device and their viability for determining the location of the plasma boundary

Kamiya, Kensaku; Ida, Katsumi*; Yoshinuma, Mikiro*; Suzuki, Chihiro*; Suzuki, Yasuhiro*; Yokoyama, Masayuki*; LHD Experimental Group*

Nuclear Fusion, 53(1), p.013003_1 - 013003_9, 2013/01

 Times Cited Count:15 Percentile:35.31(Physics, Fluids & Plasmas)

This paper provides and proposes a new technique to determine the location of the LCFS that is based on a characterization of the $$E$$$$_{r}$$ structure derived from CXS measurements in the LHD. We found that the spatial derivative in the $$E$$$$_{r}$$ structure had the local maximum value at the region very near, or possibly outside the vacuum LCFS location of vacuum magnetic field at the outer midplane in the low $$beta$$ plasma.

Journal Articles

Modifications to the edge radial electric field by angular momentum injection in JT-60U and their implication for pedestal transport

Kamiya, Kensaku; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; et al.

Nuclear Fusion, 52(11), p.114010_1 - 114010_12, 2012/10

 Times Cited Count:9 Percentile:56.6(Physics, Fluids & Plasmas)

Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the $$E$$$$_{r}$$-well region. The shear in the edge $$E$$$$_{r}$$ becomes wider in the co-NBI case, while the edge $$E$$$$_{r}$$-well becomes deeper in the counter-NBI case.

Journal Articles

Reduction of ion thermal diffusivity inside a magnetic island in JT-60U tokamak plasma

Ida, Katsumi*; Kamiya, Kensaku; Isayama, Akihiko; Sakamoto, Yoshiteru; JT-60 Team

Physical Review Letters, 109(6), p.065001_1 - 065001_4, 2012/08

 Times Cited Count:34 Percentile:15.97(Physics, Multidisciplinary)

The transport inside the magnetic island is investigated in the plasma during the transient phase after the back transition from $$H$$-mode to $$L$$-mode, where a sudden drop of temperature outside the magnetic island causes a peaking of ion temperature at the $$O$$-point inside the magnetic island.

Journal Articles

Estimation of tensile strengths at 4K of 316LN forging and hot rolled plate for the ITER toroidal field coils

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Chida, Yutaka; Nakajima, Hideo

AIP Conference Proceedings 1435, p.70 - 77, 2012/06

A prediction method for tensile strengths at liquid helium temperature (4K) has been developed in order to rationalize qualification tests of cryogenic structural materials used in large superconducting magnet for a fusion device. This method is to use quadratic curves which are expressed as a function of carbon and nitrogen contents and strengths at room temperature. This study shows results of tensile tests at 4K and confirmation of accuracy of prediction method for tensile strengths at 4K for large forgings and thick hot rolled plates of austenitic stainless steels, which can be used in the actual coil case and radial plates of the ITER toroidal field coils. These products are 316LN having high nitrogen from 0.09 to 0.24% and maximum thickness is 600mm. As the results, it was confirmed that the tensile strengths of these products at 4K can be predicted by using appropriate quadratic curves. And distribution of strengths for each product was estimated.

Journal Articles

Development of structures for ITER toroidal field coil in Japan

Iguchi, Masahide; Chida, Yutaka; Takano, Katsutoshi; Kawano, Katsumi; Saito, Toru; Nakajima, Hideo; Koizumi, Norikiyo; Minemura, Toshiyuki*; Ogata, Hiroshige*; Ogawa, Tsuyoshi*; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4203305_1 - 4203305_5, 2012/06

 Times Cited Count:8 Percentile:51.1(Engineering, Electrical & Electronic)

Japan Atomic Energy Agency (JAEA) has responsibility to procure 19 structures for ITER toroidal field (TF) coils as in-kind components. JAEA plans to use materials specified in the material section of "Codes for Fusion Facilities; Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in 2008. Large forged products were produced and their mechanical properties at 4K were evaluated. In addition, the following activities have been performed; (1) to optimize the design of each weld type identified in the manufacturing sequence, (2) to qualify typical welding procedure including repair, (3) to establish welding techniques other than narrow gap TIG welding with FMYJJ1, (4) to demonstrate the manufacturing procedures through manufacture of 1-m mockups and full-scale segments of TFC structure. This paper describes the results of material qualification and industrialization activities of manufacturing processes of ITER TFC structure.

Journal Articles

1st Asia-Pacific Transport Working Group (APTWG) Meeting

Ida, Katsumi*; Dong, J. Q.*; Kikuchi, Mitsuru; Kwon, J. M.*; Diamond, P. H.*

Nuclear Fusion, 52(2), p.027001_1 - 027001_10, 2012/02

This conference report summarizes the contributions to, and discussions at, the 1st Asia-Pacific Transport Working Group Meeting held in Toki, Japan, on 14-17 June 2011. The topics of the meeting were organized under four main headings: momentum transport, non-locality in transport, edge turbulence and L to H transition and 3D effects on transport physics. The events which initiated this meeting are also described in this report.

Journal Articles

Evaluation of water distribution in a small operating fuel cell using neutron color image intensifier

Yasuda, Ryo; Nitto, Koichi*; Konagai, Chikara*; Shiozawa, Masahiro*; Takenaka, Nobuyuki*; Asano, Hitoshi*; Murakawa, Hideki*; Sugimoto, Katsumi*; Nojima, Takehiro; Hayashida, Hirotoshi; et al.

Nuclear Instruments and Methods in Physics Research A, 651(1), p.268 - 272, 2011/09

 Times Cited Count:7 Percentile:45.23(Instruments & Instrumentation)

Neutron radiography is one of useful tools to visualize water behavior in fuel cells under operation. In order to observe the detailed information about the water distribution in MEA and GDL in fuel cells, a high spatial resolution and high sensitivity neutron imaging system are required. We developed an imaging system using the neutron color imaging intensifier and continuously observed water distribution in operating a fuel cell. By using the system, a small type fuel cell under operation was continuously observed at the TNRF in every 20 sec. In the results, the water area was appeared from GDL and MEA, and expanded to the channel of the cathode side. On the other hand, voltage was gradually reduced with the operation time, and steeply dropped. It is considered that voltage drop was caused by blockage of gas flow due to the piling up water in the channel of the cathode side.

Journal Articles

Fabrication and characterization of silicon nitride-based inert matrix fuels sintered with magnesium silicates

Usuki, Toshiyuki; Yoshida, Katsumi*; Yano, Toyohiko*; Miwa, Shuhei; Osaka, Masahiko

Progress in Nuclear Energy, 53(7), p.1078 - 1081, 2011/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

The effects of sintering additives of magnesium silicates, i.e. enstatite (MgSiO$$_{3}$$), steatite (MgSiO$$_{3}$$) and forsterite (Mg$$_{2}$$SiO$$_{4}$$), on the fabrication properties and characteristics of the silicon nitride ceramics based inert matrix fuels were experimentally investigated. CeO$$_{2}$$ was selected as simulating element of AmO$$_{2}$$. Sintered pellets were characterized in term of their densities, thermal conductivities and solubility to nitric acid. The densifications of sintered bodies were enhanced by using additives of magnesium silicates at relative low sintering temperature. The relative density of silicon nitride ceramics based inert matrix fuels with forsterite were achieved above 90% at 1723 K. The thermal conductivities of silicon nitride ceramics based inert matrix fuels varied according to sintering temperature, and those sintered at 1923 K were above 34 W/m K. The grain boundary phases in Silicon nitride ceramics based inert matrix fuels found to be dissolved into HNO$$_{3}$$.

Journal Articles

Spatio-temporal structure of the edge radial electric field during H-mode in JT-60U

Kamiya, Kensaku; Sakamoto, Yoshiteru; Matsunaga, Go; Kojima, Atsushi; Urano, Hajime; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; Ida, Katsumi*; Kurki-Suonio, T.*; et al.

Nuclear Fusion, 51(5), p.053009_1 - 053009_3, 2011/05

 Times Cited Count:12 Percentile:47.24(Physics, Fluids & Plasmas)

We revisited to measure the edge impurity ion dynamic with new CXRS in the hot ion H-mode regime at the high magnetic field having two steps transition where a jump of Ti gradient precedes a jump of impurity Vp. Two discrete phases with different magnitude of Er in the H-phase have been observed. One is the intermediate H-phase having a large Ti gradients without significant Vp of impurity species with moderate magnitude of Er, and the other is the complete H-phase characterized by a large Er.

Journal Articles

Integrated transport simulation of LHD plasmas using TASK3D

Wakasa, Arimitsu*; Fukuyama, Atsushi*; Murakami, Sadayoshi*; Miki, Masayuki*; Yokoyama, Masayuki*; Sato, Masahiko*; Toda, Shinichiro*; Funaba, Hisamichi*; Tanaka, Kenji*; Ida, Katsumi*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Journal Articles

Basic concept of JT-60SA tokamak assembly

Shibanuma, Kiyoshi; Arai, Takashi; Kawashima, Hisato; Hoshino, Katsumichi; Hoshi, Ryo; Kobayashi, Kaoru; Sawai, Hiroaki; Masaki, Kei; Sakurai, Shinji; Shibama, Yusuke; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.276 - 281, 2010/08

The JT-60 SA project is a combined project of JA-EU satellite tokamak program under the Broader Approach (BA) agreement and JA domestic program. Major components of JT-60SA for assembly are vacuum vessel (VV), superconducting coils (TF coils, EF coils and CS coil), in-vessel components such as divertor, thermal shield and cryostat. An assembly frame (with the dedicated cranes), which is located around the tokamak, is adopted to carry out effectively the assembly of tokamak components in the tokamak hall, independently of the facility cranes in the building. The assembly frame also provides assembly tools and jigs with jacks to support temporarily the components as well as to adjust the components at right positions. In this paper, the assembly scenario and scequence of the major components such as VV and TFC and the concept of the assembly frame including special jigs and fixtures are discussed.

120 (Records 1-20 displayed on this page)