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Yoshida, Masafumi; Tanabe, Tetsuo*; Adachi, Ayumu*; Hayashi, Takao; Nakano, Tomohide; Fukumoto, Masakatsu; Yagyu, Junichi; Miyo, Yasuhiko; Masaki, Kei; Itami, Kiyoshi
Journal of Nuclear Materials, 438, p.S1261 - S1265, 2013/07
Times Cited Count：6 Percentile：44.02(Materials Science, Multidisciplinary)Fuel retention rates and carbon re-deposition rates in the plasma shadowed areas in JT-60U were measured. Distributions of the fuel retention as well as the carbon re-deposition in the whole in-vessel of a large tokamak were clarified for the first time in the world. The fuel retention in the plasma shadowed areas was about two times larger than that in the carbon re-deposited layers on the plasma facing surface, although the amount of the carbon re-deposited on the plasma shadowed areas were about a half of that on the plasma facing surface, because of relatively lower temperature in the shadow areas causing higher hydrogen saturation concentration in the carbon re-deposited layers. The total fuel retention rate in JT-60U, including previously measured for all plasma facing areas, was evaluated to be 1.3
10
H+Ds
, which was lower than that in other devices, due to probably to higher temperature operation in JT-60U.
Yoshida, Masafumi; Tanabe, Tetsuo*; Hayashi, Takao; Nakano, Tomohide; Fukumoto, Masakatsu; Yagyu, Junichi; Miyo, Yasuhiko; Masaki, Kei; Itami, Kiyoshi
Fusion Science and Technology, 63(1T), p.367 - 370, 2013/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In this study, the retentions of hydrogen isotopes (H and D) in the gaps in JT-60U are clarified. Carbon tiles used in 1992-2004 were poloidally and toroidally taken out from outboard first wall in JT-60U to measure the retentions. The H and D retentions in the samples were measured by thermal desorption spectrometry (TDS). The H+D retention in the top side was higher than that of the bottom side, which might be due to thicker re-deposited carbon layers on the surface of the top side. The retentions in the surface of the side surfaces were slightly lower than that in the plasma facing surface where the retention was saturated to be 3-4e22 atoms/m
. The retention rate was evaluated to be 3e17 H+D atoms/m/s from the measured retentions in two different discharge times by assuming the retention to increase linearly with the discharge time.
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
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：5 Percentile：38.65(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.
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
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
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
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 
C, decreased gradually at 150 C, and remained constant at 80 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.
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
H
and CH
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. The photon emissions of C from CH (CH) decay faster than that of CH from CH in high-temperature (
10 eV) plasmas, which reproduces the difference of the decay of the CD and C 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, is in good agreement with the values observed in JT-60U experiments.
Yoshida, Masafumi; Tanabe, Tetsuo*; Nobuta, Yuji*; Hayashi, Takao; Masaki, Kei; Sato, Masayasu
Journal of Nuclear Materials, 390-391, p.635 - 638, 2009/06
Times Cited Count：9 Percentile：53.3(Materials Science, Multidisciplinary)We have investigated hydrogen isotopes retention in the outboard first wall tiles of JT-60U by means of TDS, SIMS and SEM. The outboard first wall tiles of JT-60U are mostly eroded. The total retention (H+D) normalized by a unit area and integrated NBI time in the eroded first wall tiles and the eroded divertor tiles were nearly the same, in spite of the lower temperature of the first wall. Differently from divertor tiles, in which H retention was dominated owing to HH discharges preformed after DD discharges, deuterium is dominated in hydrogen isotopes retention and penetrates deeper from the surface. This is attributed to injection of high energy D and difficulty of isotopic replacement owing to their lower temperature. The integrated amount over the whole surface could be appreciably large. This type of hydrogen retention could be also possible for the metallic wall.
Nobuta, Yuji*; Arai, Takashi; Yagyu, Junichi; Masaki, Kei; Sato, Masayasu; Tanabe, Tetsuo*; Yamauchi, Yuji*; Hino, Tomoaki*
Journal of Nuclear Materials, 390-391, p.643 - 646, 2009/06
Times Cited Count：5 Percentile：35.97(Materials Science, Multidisciplinary)The hydrogen and deuterium retention in gap side surfaces of the first wall tiles exposed to DD and HH discharges in JT-60U were investigated. The hydrogen and deuterium retention and boron deposition increased with the gap width. The depth profile of deuterium was very similar to that of boron, indicating that deuterium was incorporated with boron. Thick carbon deposition layer (
1e
m) was observed in the gap of inboard tile and the atomic ratio in (H+D)/C at the carbon layer was estimated to be approximately 0.15. This value is higher than that observed in the divertor region. In this study, the H+D amount in gap side surfaces of the first wall was of the order of 1e23 1e24m
.
Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Shibahara, Takahiro*; Hirohata, Yuko*; Yoshida, Masafumi; Masaki, Kei; Sato, Masayasu
Journal of Nuclear Materials, 390-391, p.705 - 708, 2009/06
Times Cited Count：8 Percentile：49.52(Materials Science, Multidisciplinary)no abstracts in English
Hayashi, Takao; Sugiyama, Kazuyoshi*; Mayer, M.*; Krieger, K.*; Masaki, Kei; Tanabe, Tetsuo*; Sato, Masayasu
Journal of Nuclear Materials, 390-391, p.667 - 670, 2009/05
Times Cited Count：1 Percentile：10.22(Materials Science, Multidisciplinary)Absolute concentrations and the depth profiles of D in plasma-facing graphite tiles used in JT-60U were determined by means of the D(
He, p)
He resonant nuclear reaction. The analyzed samples were not exposed to H discharges before air ventilation. The maximum depth of analysis is about 1.4 10
carbon (C) atoms/m, corresponding to a linear depth of 16 
m for the density of 1.7 10 kg/m. The highest D concentration was found at the inboard mid-plane of first wall area. The maximum D concentration is D/C=0.13, and the concentration decrease with the depth. The D retention within 16 m is 1.9 10
D atoms/m. The D retentions in this paper were about 29 times larger than previous samples, which were located on the same area and exposed to the hydrogen discharges. This indicates the H plasma discharges were effective to remove the D (and T) from graphite tiles in the first wall area.
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
Kawahata, Kazuo*; Kawano, Yasunori; Kusama, Yoshinori; Mase, Atsushi*; Sasao, Mamiko*; Ide, Shunsuke; Oikawa, Toshihiro; Suzuki, Takahiro; Takase, Yuichi*; Nakamura, Yukio*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 84(5), p.297 - 298, 2008/05
no abstracts in English
Masaki, Kei; Tanabe, Tetsuo*; Hirohata, Yuko*; Oya, Yasuhisa*; Shibahara, Takahiro*; Hayashi, Takao; Sugiyama, Kazuyoshi*; Arai, Takashi; Okuno, Kenji*; Miya, Naoyuki
Nuclear Fusion, 47(11), p.1577 - 1582, 2007/11
Times Cited Count：14 Percentile：45.18(Physics, Fluids & Plasmas)In JT-60U, erosion/deposition analyses for the plasma facing wall have shown that deposition was dominant at the inner-middle first wall and the inner divertor, whereas erosion dominant at the upper first wall and the outer divertor. Assuming toroidal symmetry in the erosion and deposition patterns, the net carbon erosion and deposition in the divertor area were estimated to be 0.34 kg and 0.55 kg, respectively. In a whole, the increment of carbon in the divertor region was 0.21 kg, which should be originated from the first wall. The hydrogen concentration in the thick deposition layer of the inner divertor was 0.02 in (H+D)/C. In the plasma-shadowed area underneath the divertor region at around 420 K, re-deposited layers of 2 m-thick were found with high hydrogen concentration of 0.8 in (H+D)/C. The carbon deposition rate in the plasma-shadowed area, however, was 810
atoms/s, which was one order smaller than that (610 atoms/s) on the wall surface.
Oya, Yasuhisa*; Hirohata, Yuko*; Nakahata, Toshihiko*; Suda, Taichi*; Yoshida, Masashi*; Arai, Takashi; Masaki, Kei; Okuno, Kenji*; Tanabe, Tetsuo*
Fusion Science and Technology, 52(3), p.554 - 558, 2007/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)To investigate retention characteristics of hydrogen isotopes in the first wall tiles of JT-60U, surface morphology, erosion/deposition profiles and hydrogen isotope retentions were examined by SEM, XPS, TDS and SIMS. It was found that poloidal deuterium retention profile was rather uniform, while the thermal desorption behavior of deuterium was quite different depending on the locations of the tiles. Deuterium retained in the upper first wall, where was covered by thick boron layers with high concentration of B, was desorbed at lower temperature than that in the lower area covered by carbon layers with much less B content. D/H ratio in the first wall tiles was appreciably higher than that observed in the divertor tiles, suggesting the injection of high energy deuteron originating from NBI into the first wall. In addition, the lower temperature of the first wall compared to that of the divertor tiles would prohibit desorption of the implanted deuterium and/or its replacement by subsequent D or H impingement.
Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09
This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).
D ion irradiationWakai, Eiichi; Ezawa, Tadashi*; Takenaka, Tsuyoshi*; Imamura, Junko*; Tanabe, Tetsuo*; Oshima, Ryuichiro*
Journal of Nuclear Materials, 367-370(1), p.478 - 482, 2007/08
Times Cited Count：7 Percentile：47.34(Materials Science, Multidisciplinary)no abstracts in English
He, p)He resonant nuclear reactionHayashi, Takao; Sugiyama, Kazuyoshi*; Krieger, K.*; Mayer, M.*; Alimov, V. Kh.*; Tanabe, Tetsuo*; Masaki, Kei; Miya, Naoyuki
Journal of Nuclear Materials, 363-365, p.904 - 909, 2007/06
Times Cited Count：11 Percentile：61.1(Materials Science, Multidisciplinary)The absolute concentrations and the depth profiles of deuterium in plasma-facing graphite tiles used in JT-60U were determined by means of the D(He, p)He resonant nuclear reaction. The highest deuterium concentration was found at a plasma-facing surface near the outer pumping slot on the outer dome wing tile, where redeposited layers with thicknesses in the micron or submicron range were observed, indicating deuterium codepostion with carbon. In addition, a high flux of high energy deuterium originating from NBI is expected on the outer dome wing as well as on the dome top tile, and could have some contribution to this area of highest deuterium retention. The deuterium content integrated up to about 16 m was 
2.510 D/m. The depth profile has a broad peak in the atomic ratio of D/C0.05 at a depth of about 2.5 m. This is mainly because D retained in the top surface was replaced by H due to isotope exchange during H discharges, which were carried out to remove tritium from the plasma-facing wall before air ventilation. In erosion dominated areas such as the outer divertor tiles, the amount of deuterium was one order of magnitude lower than that on the outer dome wing tile. In the first wall area, the highest amount of deuterium with a content of 1.010 D/m was found in the upper region, nearest to the plasma. Again implantation of high energy deuterium due to NBI could have some contribution to the high deuterium retention.
