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Alimov, V.; Shu, Wataru*; Roth, J.*; Sugiyama, Kazuyoshi*; Lindig, S.*; Balden, M.*; Isobe, Kanetsugu; Yamanishi, Toshihiko
Physica Scripta, T138, p.014048_1 - 014048_5, 2009/12
Times Cited Count：123 Percentile：95.28(Physics, Multidisciplinary)Blistering and deuterium retention in re-crystallized tungsten exposed to low-energy, high flux (10
D/m
s) pure and helium-seeded D plasmas to a fluence of 10
D/m have been examined with scanning electron microscopy, thermal desorption spectroscopy (TDS), and the D(
He,p)
He nuclear reaction at a He energy varied from 0.69 to 4.0 MeV. In the case of exposure to pure D plasma (38 eV/D), blisters with various shapes and sizes depending on the exposure temperature are found on the W surface. No blisters appear at temperatures above 700 K. The deuterium retention increases with the exposure temperature, reaching a maximum value of about 10 D/m at 480 K, and then decreases as the temperature rises further. Seeding of helium into the D plasma to the He ion concentration of 0.2 and 5% significantly reduces the D retention at elevated temperatures and prevents formation of the blisters.
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 2
9 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.
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.
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.
Sugiyama, Kazuyoshi*; Hayashi, Takao; Krieger, K.*; Mayer, M.*; Masaki, Kei; Miya, Naoyuki; Tanabe, Tetsuo*
Journal of Nuclear Materials, 363-365, p.949 - 954, 2007/06
Times Cited Count：10 Percentile：58.16(Materials Science, Multidisciplinary)no abstracts in English
Masaki, Kei; Tanabe, Tetsuo*; Hirohata, Yuko*; Oya, Yasuhisa*; Shibahara, Takahiro*; Hayashi, Takao; Sugiyama, Kazuyoshi*; Arai, Takashi; Okuno, Kenji*; Miya, Naoyuki
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
Evaluation of fuel inventory and its retention process are critical issues for a next-step fusion device, especially with carbon-based wall. In order to resolve the issues, the hydrogen retention and carbon deposition analyses for the plasma facing surfaces and plasma-shadowed area of JT-60U have been performed. 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 2m-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.
Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Coad, P.*; Bekris, N.*; Glugla, M.*; Miya, Naoyuki
Journal of Nuclear Materials, 345(2-3), p.89 - 95, 2005/10
Times Cited Count：17 Percentile：73.49(Materials Science, Multidisciplinary)no abstracts in English
Masaki, Kei; Sugiyama, Kazuyoshi*; Hayashi, Takao; Ochiai, Kentaro; Goto, Yoshitaka*; Shibahara, Takahiro*; Hirohata, Yuko*; Oya, Yasuhisa*; Miya, Naoyuki; Tanabe, Tetsuo*
Journal of Nuclear Materials, 337-339, p.553 - 559, 2005/03
Times Cited Count：26 Percentile：84.04(Materials Science, Multidisciplinary)no abstracts in English
Oya, Yasuhisa*; Morimoto, Yasutomi*; Oyaizu, Makoto*; Hirohata, Yuko*; Yagyu, Junichi; Miyo, Yasuhiko; Goto, Yoshitaka*; Sugiyama, Kazuyoshi*; Okuno, Kenji*; Miya, Naoyuki; et al.
Physica Scripta, T108, p.57 - 62, 2004/00
no abstracts in English
Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Miya, Naoyuki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(2), p.130 - 139, 2003/06
no abstracts in English
Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Miyasaka, Kazutaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; et al.
Journal of Nuclear Materials, 313-316, p.514 - 518, 2003/03
Times Cited Count：55 Percentile：94.93(Materials Science, Multidisciplinary)Detailed tritium profiles on the JT-60U W-shaped divertor and first wall tiles were examined by Tritium Imaging Plate Technique (TIPT) and full combustion method. The tritium deposition image obtained by TIPT was consistent with the distribution measured by combustion method. The highest tritium concentration was 60 kBq/cm at the dome top tile. However, deposition layer was not obviously observed on the dome top tile. The tritium concentration in the inner divertor target tile was lower (2 kBq/cm) even with the thick deposition layer of 60 m. This tritium distribution can be explained by energetic triton particle loss due to ripple loss. According to the simulation using the OFMC code, 31% of the triton particles produced by D-D nuclear reaction is implanted deeply to the wall without fully losing the initial energy of 1 MeV.
Sugiyama, Kazuyoshi*; Miyasaka, Kazutaka*; Tanabe, Tetsuo*; Masaki, Kei; Goto, Yoshitaka*; Tobita, Kenji; Kodama, Kozo; Miya, Naoyuki
Physica Scripta, T103, p.56 - 58, 2003/00
Times Cited Count：14 Percentile：62.77(Physics, Multidisciplinary)no abstracts in English
Tanabe, Tetsuo*; Miyasaka, Kazutaka*; Sugiyama, Kazuyoshi*; Masaki, Kei; Kodama, Kozo; Miya, Naoyuki
Fusion Engineering and Design, 41(3), p.877 - 881, 2002/05
no abstracts in English
Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Masaki, Kei; Goto, Yoshitaka*; Tobita, Kenji; Miya, Naoyuki
IAEA-CN-94/EX/P2-11 (CD-ROM), 6 Pages, 2002/00
no abstracts in English
Shibahara, Takahiro*; Hirohata, Yuko*; Oya, Yasuhisa*; Oyaizu, Makoto*; Onishi, Yoshihiro*; Yoshikawa, Akira*; Okuno, Kenji*; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Arai, Takashi; et al.
no journal, ,
no abstracts in English
Hirohata, Yuko*; Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Shibahara, Takahiro*; Oya, Yasuhisa*; Oyaizu, Makoto*; Yoshikawa, Akira*; Okuno, Kenji*; Masaki, Kei; Arai, Takashi; et al.
no journal, ,
no abstracts in English
Yoshida, Masashi*; Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Masaki, Kei; Miya, Naoyuki; Philipps, V.*
no journal, ,
no abstracts in English
Miya, Naoyuki; Watanabe, Daisuke*; Sakawa, Yoichi*; Shibahara, Takahiro*; Sugiyama, Kazuyoshi*; Shoji, Tatsuo*; Yamazaki, Kozo*; Masaki, Kei; Tanabe, Tetsuo*
no journal, ,
no abstracts in English
Hirohata, Yuko*; Tanabe, Tetsuo*; Oya, Yasuhisa*; Shibahara, Takahiro*; Sugiyama, Kazuyoshi*; Oyaizu, Makoto*; Yoshikawa, Akira*; Yoshida, Masashi*; Arai, Takashi; Masaki, Kei; et al.
no journal, ,
no abstracts in English
