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Higashijima, Satoru; Kamada, Yutaka; Barabaschi, P.*; Shirai, Hiroshi; JT-60SA Team
Fusion Science and Technology, 68(2), p.259 - 266, 2015/09
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)
spectral bands and a re-evaluation of the chemical sputtering yield of the JT-60U carbon divertor platesNakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Asakura, Nobuyuki; Fukumoto, Masakatsu
Nuclear Fusion, 54(4), p.043004_1 - 043004_10, 2014/03
Times Cited Count：2 Percentile：11.12(Physics, Fluids & Plasmas)We have determined the CH photon emission rate defined as the number of photons over dissociation and/or ionization event of 
, from the ratio of the measured emission intensity of CH spectral band to the injection rate into the divertor plasma of JT-60U. Similar photon emission rates of CD for 
, CH and 
for 
and 
have also been determined. Interestingly, during the and the injection, the spectral band intensity increases, suggesting that injected reacts with the carbon divertor plates to form heavier hydrocarbons. From the determined emission rates, previously published chemical sputtering yields, have been reevaluated. The reevaluated total chemical sputtering yield becomes lower (
) compared to the original (
) and the dependence on the incident ion flux and energy becomes weaker.
Higashijima, Satoru; Sakurai, Shinji; Sakasai, Akira
Journal of Nuclear Materials, 417(1-3), p.912 - 915, 2011/10
Times Cited Count：8 Percentile：54.91(Materials Science, Multidisciplinary)JT-60SA divertor has to receive the maximum heat flux of 
15 MW/m
for 100 s, and JAEA have developed the monoblock-type CFC divertor target for JT-60SA. For boosting the production yield of the target, CFC cracking due to thermal expansion and contraction of the CuCrZr cooling tube should be suppressed. CuCrZr characteristics strongly depend on the heat treatment, and the target is heat-treated on the manufacturing process of brazing, solution treatment, and annealing. CuCrZr test specimens were heat-treated with the targets, and the strength and the hardness of the specimens were almost the same in the case of the quenching rates of 0.65 
C/s and 1.5 C/s around 800 C. It is clarified that the slower quenching rate is acceptable, and the half of the mock-ups at least removed high heat flux of 15 MW/m as required without the CFC cracking.
Sakurai, Shinji; Higashijima, Satoru; Hayashi, Takao; Shibama, Yusuke; Masuo, Hiroshige*; Ozaki, Hidetsugu; Sakasai, Akira; Shibanuma, Kiyoshi
Fusion Engineering and Design, 85(10-12), p.2187 - 2191, 2010/08
Times Cited Count：10 Percentile：57.61(Nuclear Science & Technology)JT-60SA tokamak project has just started construction phase under both the Japanese domestic program and the Japan-EU international program "ITER Broader Approach". All of plasma facing components (PFC) shall be actively cooled due to high power long pulse plasma heating. Lower single null closed divertor with vertical target (VT) will be installed at the start of experiment phase. Each divertor module covers a 10-degree sector in toroidal direction. PFCs such as VTs, baffles and dome shall be assembled on a divertor cassette, which provides integrated coolant pipe connection to coolant headers in the VV. Static structural analysis for dead weight, coolant pressure and EM loads shows that displacement and stress of the divertor module are generally small but a part of support structure of PFC requires improvement.
Higashijima, Satoru; Sakurai, Shinji; Suzuki, Satoshi; Yokoyama, Kenji; Kashiwa, Yoshitoshi; Masaki, Kei; Shibama, Yusuke; Takechi, Manabu; Shibanuma, Kiyoshi; Sakasai, Akira; et al.
Fusion Engineering and Design, 84(2-6), p.949 - 952, 2009/06
Times Cited Count：9 Percentile：54.57(Nuclear Science & Technology)An upgrading device of JT-60 tokamak with fully superconducting coils (JT-60SA) is constructed under both the Japanese domestic program and the international program "Broader Approach". The maximum heat flux to JT-60SA divertor is estimated to 15 MW/m for 100 s, and a monoblock-type CFC divertor armor is promising. The JT-60SA armor consists of CFC monoblocks, a cooling CuCrZr screw-tube, and a thin OFHC-Cu buffer layer, and the brazed joints are essential for the armor. Metalization inside CFC monoblock is applied for further improvement, and we confirmed again that the mock-up has heat removal capability in excess of ITER requirement. For optimization of the fabrication method and understanding of the production yield, the mock-ups corresponding to quantity produced in one furnace is also produced, and the half of the mock-ups could remove 15 MW/m as required. This summarizes the recent progress of design and mock-up test results for JT-60SA divertor armor.
Sakurai, Shinji; Kawashima, Hisato; Higashijima, Satoru; Shimizu, Katsuhiro; Masaki, Kei; Asakura, Nobuyuki; Shibama, Yusuke; Sakasai, Akira
Journal of Nuclear Materials, 390-391, p.891 - 894, 2009/06
Times Cited Count：1 Percentile：10.41(Materials Science, Multidisciplinary)The entire plasma facing components should be water-cooled in JT-60SA. A cassette module of divertor is introduced for remote maintenance. The divertor targets are mounted on the cassette. A brazed carbon fiber composite target is promising candidate for the divertor target. The latest results of mock-ups test clarified that thermal fatigue life cycles are more than 1000 cycles of 15 MW/m
10 sec. The divertor is designed to control divertor detachment for heat load reduction. The vertical targets and a "V-shaped corner" like as that in ITER are adopted to enhance detachment. Divertor heat load and pumping efficiency has been evaluated, using 2D plasma fluid (SOLDOR) and neutral Monte-Carlo (NEUT2D) code. The plasma detachment occurs near the outer-strike point within the "V-shaped corner", which results in low peak heat flux density 5.8 MW/m for the case with additional gas puff of 510
/s compared to 11.4 MW/m for the case without "V-shaped corner".
Nakano, Tomohide; Kubo, Hirotaka; Asakura, Nobuyuki; Shimizu, Katsuhiro; Kawashima, Hisato; Higashijima, Satoru
Journal of Nuclear Materials, 390-391, p.255 - 258, 2009/06
Times Cited Count：21 Percentile：80.17(Materials Science, Multidisciplinary)Therefore it is concluded that the dominant radiator, C
, is produced by ionization of C
and recombination of C
at similar rates around the X-point in the detached plasma, and that C is the second biggest radiator. Further the transport loss of C will be investigated by an impurity transport code (IMPMC), in addition to comparison of the radiation power and atomic processes.
Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.
Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12
Times Cited Count：17 Percentile：73.86(Nuclear Science & Technology)no abstracts in English
Nakano, Tomohide; Kubo, Hirotaka; Asakura, Nobuyuki; Shimizu, Katsuhiro; Higashijima, Satoru
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
It has been found that tungsten accumulation becomes more significant with increasing plasma rotation velocity against the plasma current direction, where negative radial electric field is formed. In a high density plasma at 62% of the Greenwald density, the tungsten accumulation levels decreased significantly, suggesting a shielding effect of the peripheral plasma. It has been found that 
is produced by the volume recombination of 
and the ionization of 
comparably. In contrast, the volume recombination of is not detected, and the ionization flux of is less than 1% of the generation flux. Thus, this result suggests that another loss mechanism of such as transport loss from the 
-point is significant.
in detached divertor plasmas of JT-60UNakano, Tomohide; Kubo, Hirotaka; Asakura, Nobuyuki; Shimizu, Katsuhiro; Konoshima, Shigeru; Fujimoto, Kayoko; Kawashima, Hisato; Higashijima, Satoru
Nuclear Fusion, 47(11), p.1458 - 1467, 2007/11
Times Cited Count：20 Percentile：58.68(Physics, Fluids & Plasmas)no abstracts in English
Kubo, Hirotaka; Sasaki, Akira; Moribayashi, Kengo; Higashijima, Satoru; Takenaga, Hidenobu; Shimizu, Katsuhiro; Nakano, Tomohide; Whiteford, A.*; Sugie, Tatsuo
Journal of Nuclear Materials, 363-365, p.1441 - 1445, 2007/06
Times Cited Count：6 Percentile：43.19(Materials Science, Multidisciplinary)no abstracts in English
Nakano, Tomohide; Kubo, Hirotaka; Asakura, Nobuyuki; Shimizu, Katsuhiro; Konoshima, Shigeru; Fujimoto, Kayoko; Kawashima, Hisato; Higashijima, Satoru
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
Volume recombination of C and 
into C is observed for the first time in detached plasmas with MARFE. It is found that the recombination flux of C to C is comparable to the ionization flux of C to C, and that the recombination zone is above an X-point and beneath the ionization zone. This result suggests that this volume recombination predominantly produces C ions, which contribute 60-80 % to the total radiation power in the divertor plasma.
Asakura, Nobuyuki; Kawashima, Hisato; Shimizu, Katsuhiro; Sakurai, Shinji; Fujita, Takaaki; Takenaga, Hidenobu; Nakano, Tomohide; Kubo, Hirotaka; Higashijima, Satoru; Hayashi, Takao; et al.
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
Divertor design for the JT-60 SA has been progressing in order to handle large heat flux during full pulse duration of 100 s. Divertor should be suitable for single null plasma experiments with the full power injection of 41 MW. The simulation results using 2D fluid (plasma) and Monte-Carlo (neutral) code are summarized. Lower single-null divertor is designed for ITER-like plasma configuration in order to study physics concept of the ITER divertor: control of the plasma detachment. Simulation results for various divertor geometries showed that the vertical target with V-shaped corner can produce plasma detachment near the outer strike-point for medium edge plasma density. It was also demonstrated that the divertor plasma became attached to move the outer strike point above the V-corner, suggesting that recover from sever detachment can be achieved by changing the plasma location. USN divertor will be designed for high-
plasma experiments with the highest shaping plasma of S=6.
Nakano, Tomohide; Asakura, Nobuyuki; Takenaga, Hidenobu; Kubo, Hirotaka; Miura, Yukitoshi; Shimizu, Katsuhiro; Konoshima, Shigeru; Masaki, Kei; Higashijima, Satoru; JT-60 Team
Nuclear Fusion, 46(5), p.626 - 634, 2006/05
Times Cited Count：20 Percentile：56.61(Physics, Fluids & Plasmas)In order to understand plasma-wall interactions in a long time scale, the discharge pulse length has been extended from 15 s to 65 s, with the NB-heating duration extended to 30 s. Nearly-saturation of the divertor plates was observed in the latter half of long pulse ELMy H-mode discharges. Particle sink into the divertor plates gradually decreased, and subsequently, wall-pumping efficiency became zero. This wall saturation resulted in a rise of the main plasma density without any auxiliary particle supply besides NB with divertor-pumping. Even when the total injected energy reached up to 350 MJ in a discharge, neither sudden increase of carbon generation such as carbon bloom nor increase of the dilution of the main plasma was observed.
Isobe, Kanetsugu; Nakamura, Hirofumi; Kaminaga, Atsushi; Tsuzuki, Kazuhiro; Higashijima, Satoru; Nishi, Masataka; Kobayashi, Yasunori*; Konishi, Satoshi*
Fusion Engineering and Design, 81(1-7), p.827 - 832, 2006/02
Times Cited Count：11 Percentile：61.07(Nuclear Science & Technology)Exhaust gas from JT-60U during experimental operation has been measured with Gas Chromatography (GC), and the gas exhaust characteristic from JT-60U on plasma discharge conditions has been investigated during the JT-60U experimental campaign in 2003-2004. During experimental operation of JT-60U, hydrogen isotope concentration strongly depended on the type of discharges such as high performance, long pulse and so on. On the other hand, impurity species, such as helium, hydrocarbon and carbon oxide, were detected during plasma discharges occasionally. During the experimental operation, plasma disruption remarkably tended to produce high concentration impurities. Glow discharge and Taylor discharge for wall conditioning also produced impurities. In the case of normal plasma, impurity was detected and high performance plasma, such as high plasma, tended to produce high concentration impurities. This result indicated that impurities concentration might be higher in the case of normal plasma in ITER, because of its high performance.
Nakamura, Hirofumi; Higashijima, Satoru
Shinku, 49(2), p.62 - 68, 2006/02
no abstracts in English
Takenaga, Hidenobu; Asakura, Nobuyuki; Kubo, Hirotaka; Higashijima, Satoru; Konoshima, Shigeru; Nakano, Tomohide; Oyama, Naoyuki; Porter, G. D.*; Rognlien, T. D.*; Rensink, M. E.*; et al.
Nuclear Fusion, 45(12), p.1618 - 1627, 2005/12
Times Cited Count：18 Percentile：52.11(Physics, Fluids & Plasmas)no abstracts in English
Nakano, Tomohide; Koide, Yoshihiko; Honda, Atsushi; Umeda, Naotaka; Akino, Noboru; Higashijima, Satoru; Takenaga, Hidenobu; Kubo, Hirotaka
Purazuma, Kaku Yugo Gakkai-Shi, 81(9), p.708 - 716, 2005/09
no abstracts in English
Isobe, Kanetsugu; Nakamura, Hirofumi; Kaminaga, Atsushi; Higashijima, Satoru; Nishi, Masataka; Konishi, Satoshi*; Nishikawa, Masabumi*; Tanabe, Tetsuo*
Fusion Science and Technology, 48(1), p.302 - 305, 2005/07
Times Cited Count：5 Percentile：36.25(Nuclear Science & Technology)no abstracts in English
Kubo, Hirotaka; Takenaga, Hidenobu; Sawada, Keiji*; Nakano, Tomohide; Kobayashi, Shinji*; Higashijima, Satoru; Asakura, Nobuyuki; Shimizu, Katsuhiro
Journal of Nuclear Materials, 337-339, p.161 - 165, 2005/03
Times Cited Count：15 Percentile：70.57(Materials Science, Multidisciplinary)no abstracts in English
