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Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:17 Percentile:5.27(Materials Science, Multidisciplinary)

Journal Articles

Deuterium retention in tungsten coating layers irradiated with deuterium and carbon ions

Fukumoto, Masakatsu; Nakano, Tomohide; Ueda, Yoshio*; Itami, Kiyoshi; Kubo, Hirotaka

Journal of Nuclear Materials, 462, p.354 - 359, 2015/07

 Times Cited Count:2 Percentile:69.57(Materials Science, Multidisciplinary)

Journal Articles

Development of divertor simulation research in the GAMMA 10/PDX tandem mirror

Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

Journal Articles

Chemical binding states of carbon atoms migrated in tungsten coating layer exposed to JT-60U divertor plasmas

Fukumoto, Masakatsu; Nakano, Tomohide; Ueda, Yoshio*; Itami, Kiyoshi

Plasma and Fusion Research (Internet), 8, p.1405159_1 - 1405159_8, 2013/11

Journal Articles

Characteristics of tungsten and carbon dusts in JT-60U and evaluation of hydrogen isotope retention

Ashikawa, Naoko*; Asakura, Nobuyuki; Fukumoto, Masakatsu; Hayashi, Takao; Ueda, Yoshio*; Muroga, Takeo*

Journal of Nuclear Materials, 438, p.S664 - S667, 2013/07

 Times Cited Count:5 Percentile:48.88(Materials Science, Multidisciplinary)

In this study, W concentrations of dusts at P-8 section and hydrogen isotope retentions in dusts are analyzed. Compositions of C including W material dusts were observed in JT-60U. For an enhanced resolution of the XPS measurement to analyze quantitatively the composition of the dust flakes, the new analysis using XPS with indium foil was done and showed that the dust flakes contains about less than 1% of tungsten in carbon. Compositions of tungsten-carbon mixed dusts at different poloidal positions are reported. Produced areas of dust including W is estimated on the outer doom wing by IMPGYRO code. Relative intensities at low temperature regions were smaller than bulk divertor target, which may be caused by the high baking/operation temperature. Amounts of retained Hydrogen/Deuterium in dust particles depend on internal defects and carbon composition of dusts.

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Effects of carbon impurity on deuterium retention in VPS-tungsten coatings exposed to JT-60U divertor plasmas

Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Nuclear Materials, 415(Suppl.1), p.S705 - S708, 2011/08

 Times Cited Count:3 Percentile:67.22(Materials Science, Multidisciplinary)

Tungsten coating on the first wall in ITER is proposed to reduce in-vessel tritium retention. However, it is possibility that carbon based materials would be used at high heat load components such as limiter. To predict the tritium retention in tungsten coating, it is essential to investigate the effects of carbon impurity on deuterium retention in tungsten coating. In this study, effects of carbon impurity on deuterium retention in the tungsten coating exposed to JT-60U divertor plasmas were investigated. Deuterium was trapped by carbon which was implanted and accumulated in the tungsten coating during the plasma discharge. D/C ration of 0.04-0.08 in the tungsten coating was reached to 1/2-1/4 compared to T/C ration in carbon co-deposition layer. Therefore, simultaneous use of carbon armor materials and tungsten coating would enhance tritium retention in tungsten coating.

Journal Articles

Report on ITPA meeting, 33

Asakura, Nobuyuki; Ashikawa, Naoko*; Ueda, Yoshio*; Ono, Noriyasu*; Tanabe, Tetsuo*; Nakano, Tomohide; Masuzaki, Suguru*; Itami, Kiyoshi; Kawano, Yasunori; Kawahata, Kazuo*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 87(7), p.485 - 486, 2011/07

no abstracts in English

Journal Articles

Heat and particle control

Asakura, Nobuyuki; Sakamoto, Yoshiteru; Ueda, Yoshio*

Purazuma, Kaku Yugo Gakkai-Shi, 87(Suppl.), p.98 - 111, 2011/02

no abstracts in English

Journal Articles

Deuterium retention in tungsten coating on the CFC tiles exposed to JT-60U divertor plasmas

Fukumoto, Masakatsu; Nakano, Tomohide; Masaki, Kei; Itami, Kiyoshi; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Plasma and Fusion Research SERIES, Vol.9, p.369 - 374, 2010/08

no abstracts in English

Journal Articles

28th report on the ITPA (International Tokamak Physics Activity) meeting

Asakura, Nobuyuki; Nakano, Tomohide; Masuzaki, Takashi*; Ashikawa, Naoko*; Ueda, Yoshio*; Tanabe, Tetsuo*; Ono, Noriyasu*

Purazuma, Kaku Yugo Gakkai-Shi, 86(2), P. 124, 2010/02

no abstracts in English

Journal Articles

Tungsten accumulation in H-mode plasmas of JT-60U

Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Yanagibayashi, Jun*; Ueda, Yoshio*

Nuclear Fusion, 49(11), p.115024_1 - 115024_10, 2009/11

 Times Cited Count:20 Percentile:31.55(Physics, Fluids & Plasmas)

It has been observed that with increasing toroidal rotation velocity inside the $$q=1$$ layer in the direction opposite to the plasma current, sawtooth activity becomes moderate and tungsten accumulation becomes significant. The tungsten accumulation level is significantly reduced from this trend in the case that electron cyclotron wave or high energy neutral beam is injected into the plasma core. In contrast, the tungsten accumulation is kept high by the electron cyclotron wave injection into the peripheral region.

Journal Articles

Experimental studies on in-vessel tritium inventory in complicated environment of fusion reactors

Ueda, Yoshio*; Hino, Tomoaki*; Ono, Noriyasu*; Takagi, Ikuji*; Nakano, Tomohide; Tanabe, Tetsuo*; Kajita, Shin*; Fukumoto, Masakatsu

Purazuma, Kaku Yugo Gakkai-Shi, 85(10), p.684 - 694, 2009/10

Relation between deuterium retention, wall temperature and hydrocarbon generation in 30-s H-mode discharges of JT-60U was described. In discharges with a density below 50% of the Greenwald density, the trend of the deuterium retention against pulse number depended on the wall temperature: with increasing pulse number, the deuterium retention decreased at a wall temperature of 300 $$^{circ}$$C, decreased gradually at 150 $$^{circ}$$C, and remained constant at 80 $$^{circ}$$C. In contrast, in discharges with high densities above 70% of the Greenwald density, the deuterium retention increased with increasing pulse number at the above three wall temperatures. In the high density discharges, the deuterium retention flux increased with increasing hydrocarbon generation flux, suggesting that the deuterium is retained in co-deposition layers of carbon, which originated from the hydrocarbons.

Journal Articles

Transport of heavy hydrocarbon and its redeposition on plasma facing walls

Oya, Kaoru*; Inai, Kensuke*; Kikuhara, Yasuyuki*; Nakano, Tomohide; Kawata, Jun*; Kawazome, Hayato*; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Plasma and Fusion Research SERIES, Vol.8, p.419 - 424, 2009/09

Redeposition of C$$_{2}$$H$$_{4}$$ and C$$_{2}$$H$$_{6}$$ chemically eroded from carbon walls is simulated by EDDY code incorporated with the reflection on a hydrogenated and amorphized carbon surface. The redeposition rate for heavy hydrocarbons is drastically decreased by introduction of the reflection. The redeposition patterns on the surface are enlarged by the reflection, but it is narrower for the heavy hydrocarbons than for CH$$_{4}$$. The photon emissions of C$$_{2}$$ from C$$_{2}$$H$$_{4}$$ (C$$_{2}$$H$$_{6}$$) decay faster than that of CH from CH$$_{4}$$ in high-temperature ($$>$$10 eV) plasmas, which reproduces the difference of the decay of the CD and C$$_{2}$$ light intensities observed in the vicinity of the outer diverter plates of JT-60U. For such temperatures, the inverse photon-efficiency, which is defined as the ratio of the number of the launching hydrocarbons to the photoemission events of CH and C$$_{2}$$, is in good agreement with the values observed in JT-60U experiments.

Journal Articles

Report on ITPA meetings, 24

Idomura, Yasuhiro; Yoshida, Maiko; Yagi, Masatoshi*; Tanaka, Kenji*; Hayashi, Nobuhiko; Sakamoto, Yoshiteru; Tamura, Naoki*; Oyama, Naoyuki; Urano, Hajime; Aiba, Nobuyuki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(12), p.952 - 955, 2008/12

no abstracts in English

Journal Articles

Localized tungsten deposition in divertor region in JT-60U

Ueda, Yoshio*; Fukumoto, Masakatsu*; Watanabe, Jun*; Otsuka, Yusuke*; Arai, Takashi; Asakura, Nobuyuki; Nobuta, Yuji*; Sato, Masayasu; Nakano, Tomohide; Yagyu, Junichi; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

Deposition profiles of tungsten released from the outer divertor were studied in JT-60U. A neutron activation method was used for the first time to accurately measure deposited tungsten. Surface density of tungsten in the thick carbon deposition layer can be measured by this method. Tungsten was mainly deposited on the inner divertor (around inner strike points) and on the outer wing of the dome. Toroidal distribution of the W deposition was significantly localized near the tungsten released position, while other metallic impurities such as Fe, Cr, Ni were distributed more uniformly. These data indicate that inward drift in the divertor region played a significant role in tungsten transport in JT-60U.

Journal Articles

Research and development of nuclear fusion

Ushigusa, Kenkichi; Seki, Masahiro; Ninomiya, Hiromasa; Norimatsu, Takayoshi*; Kamada, Yutaka; Mori, Masahiro; Okuno, Kiyoshi; Shibanuma, Kiyoshi; Inoue, Takashi; Sakamoto, Keishi; et al.

Genshiryoku Handobukku, p.906 - 1029, 2007/11

no abstracts in English

Journal Articles

Surface studies of tungsten erosion and deposition in JT-60U

Ueda, Yoshio*; Fukumoto, Masakatsu*; Nishikawa, Masahiro*; Tanabe, Tetsuo*; Miya, Naoyuki; Arai, Takashi; Masaki, Kei; Ishimoto, Yuki*; Tsuzuki, Kazuhiro*; Asakura, Nobuyuki

Journal of Nuclear Materials, 363-365, p.66 - 71, 2007/06

 Times Cited Count:8 Percentile:46.37(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Intelligible seminar on fusion reactors, 5; Plasma facing high-heat-flux components, Walls to withstand high heat flux from fusion plasmas

Suzuki, Satoshi; Ueda, Yoshio*

Nippon Genshiryoku Gakkai-Shi, 47(4), p.266 - 271, 2005/04

no abstracts in English

Journal Articles

Intelligible seminor on fusion reactors, 1; Introduction to fusion reactors

Ueda, Yoshio*; Inoue, Takashi; Kurihara, Kenichi

Nippon Genshiryoku Gakkai-Shi, 46(12), p.845 - 852, 2004/12

no abstracts in English

60 (Records 1-20 displayed on this page)