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Konoshima, Shigeru; Tamai, Hiroshi; Miura, Yukitoshi; Higashijima, Satoru; Kubo, Hirotaka; Sakurai, Shinji; Shimizu, Katsuhiro; Takizuka, Tomonori; Koide, Yoshihiko; Hatae, Takaki; et al.
Journal of Nuclear Materials, 313-316(1-3), p.888 - 892, 2003/03
Times Cited Count：20 Percentile：77.2(Materials Science, Multidisciplinary)The emissivity distribution of the JT-60U divertor plasmas has been studied with the bolometer diagnostics. Line integrated bolometer signals of 48 chords have been successfully mapped onto the JT-60U W-shaped divertor geometry. 2D radiation profiles provide an intuitive understanding of the experiments and comparison of experiment with simulation for divertor characterization. An extended region of the radiation along both divertor legs was found in ELMing H-mode discharges with line-average density of 3.7x10
m
. A highly radiative zone with an emissivity of around 15 MWm at the inboard side and around 8 MWm at outboard side has been identified to extend more than 10 cm from each target plate toward the x-point. About 70 % of the input neutral beam power, 11 MW, is dissipated as a divertor radiation in that region.
-drift, current, and kinetic effects on divertor plasma profiles during ELMsRognlien, T. D.*; Shimada, Michiya
Journal of Nuclear Materials, 313-316, p.1000 - 1004, 2003/03
Times Cited Count：8 Percentile：49.89(Materials Science, Multidisciplinary)Edge Localized Mode (ELM) heat load on material surfaces is a key issue for burning-plasma tokamak experiments, e.g., ITER or FIRE. When a hot and dense plasma is injected to open field lines near the midplane at an ELM event, there will be a pressure imbalance along the field line, because ion motion is slow. Therefore an electric field will develop along the field line(an extended presheath). Due to the rotational transform, the parallel electric field becomes a poloidal electric field. The field Ep generates an . Therefore, as the injected plasma flows toward the divertor surface to deposit its energy, it experiences a radial shift 1cm. As the target plate is usually inclined to reduce the heat load, a radial shift of 1 cm is appreciable. For ITER, this would correspond to 3 cm on the target. As different portions of the hot ion plasma feel different electric field, the heat flux should also spread radially. A detailed assessment of these cross-field drift effects is given for an ITER-sized device using time-dependent simulations with the 2D UEDGE transport code.
Kubo, Hirotaka; Sakurai, Shinji; Higashijima, Satoru; Takenaga, Hidenobu; Itami, Kiyoshi; Konoshima, Shigeru; Nakano, Tomohide; Koide, Yoshihiko; Asakura, Nobuyuki; Shimizu, Katsuhiro; et al.
Journal of Nuclear Materials, 313-316(1-3), p.1197 - 1201, 2003/03
Times Cited Count：19 Percentile：75.79(Materials Science, Multidisciplinary)no abstracts in English
Shu, Wataru; Kawakubo, Yukio*; Masaki, Kei; Nishi, Masataka
Journal of Nuclear Materials, 313-316(1-3), p.584 - 587, 2003/03
Times Cited Count：22 Percentile：79.74(Materials Science, Multidisciplinary)no abstracts in English
Nakamura, Hirofumi; Shu, Wataru; Hayashi, Takumi; Nishi, Masataka
Journal of Nuclear Materials, 313-316(1-3), p.679 - 684, 2003/03
Times Cited Count：17 Percentile：72.74(Materials Science, Multidisciplinary)no abstracts in English
Sato, Satoshi; Nishitani, Takeo
Journal of Nuclear Materials, 313-316, p.690 - 695, 2003/03
Times Cited Count：11 Percentile：56.43(Materials Science, Multidisciplinary)no abstracts in English
Chankin, A. V.; Asakura, Nobuyuki; Fukuda, Takeshi; Isayama, Akihiko; Itami, Kiyoshi; Kamada, Yutaka; Kubo, Hirotaka; Miura, Yukitoshi; Nakano, Tomohide; Oyama, Naoyuki; et al.
Journal of Nuclear Materials, 313-316, p.828 - 833, 2003/03
Times Cited Count：21 Percentile：78.49(Materials Science, Multidisciplinary)In JT-60U, extensive plasma-neutral exchange during a typical type I ELM leads to a transient increase in the total number of charged particles in the plasma. The density rise is especially large at the edge, with the increase in the inner vertical interferometer signal (FIR1) of up to 40%, in the case of a giant ELM. Fast measurements of edge plasma density, electron temperature, magnetic fluctuations and Bremsstrahlung emission have been conducted to study the dynamics of the ELM evolution. In order to pinpoint the exact location of the density rise, a dedicated set of experiments with the horizontal plasma sweep to scan the separatrix position at the inner midplane with respect to the FIR1 chord, has been carried out at different wall conditions.
Takizuka, Tomonori; Hosokawa, Masanari*; Shimizu, Katsuhiro
Journal of Nuclear Materials, 313-316(1-3), p.1331 - 1334, 2003/03
Times Cited Count：15 Percentile：69.06(Materials Science, Multidisciplinary)In course of tokamak fusion research, particle and heat control is one of the most crucial issues. Helium ash exhaust and impurity retention in the divertor region owe to the plasma flow towards divertor plate. The localization of heat load on the plate depends on the flow pattern. Accordingly, particle and heat control can be achieved by the proper control of the flow in SOL and divertor plasmas. In this paper, the flow control is studied with two-dimensional particle simulations by PARASOL (PARticle Advanced simulation for SOL and divertor plasmas) code. Magnetic field configuration with separatrix like a tokamak divertor configuration is given. Hot particle source is put in the core plasma. Recycling cold particle source is located near the divertor plate. Particle source of gas puff in the SOL plasma is given for the flow control. Divertor biasing is available by changing the electrostatic potential on the plates. Effects of gas puff and biasing on the flow are studied. Controllability is evaluated from simulation results.
/TiC coatingHirohata, Yuko*; Motojima, Dai*; Hino, Tomoaki*; Sengoku, Seio
Journal of Nuclear Materials, 313-316(1-3), p.172 - 176, 2003/03
Times Cited Count：13 Percentile：64.66(Materials Science, Multidisciplinary)Titanium oxide film was coated on entire surface of a V-4Cr-4Ti alloy to reduce hydrogen absorption at low temperature region. The film consisted with a mixture of TiO2 and TiC. The content of TiO was approximately 80%. The hydrogen absorption rate of Ti-oxide coated V-alloy largely decreased with increase of the film thickness. In the case of the film with a thickness of 0.5 micron, the absorption rate was fifty times smaller than that of non-coated V-alloy at the absorption temperature of 573 K.
Higashijima, Satoru; Asakura, Nobuyuki; Kubo, Hirotaka; Miura, Yukitoshi; Nakano, Tomohide; Konoshima, Shigeru; Itami, Kiyoshi; Sakurai, Shinji; Takenaga, Hidenobu; Tamai, Hiroshi; et al.
Journal of Nuclear Materials, 313-316, p.1123 - 1130, 2003/03
Times Cited Count：17 Percentile：72.74(Materials Science, Multidisciplinary)Reduction of steady-state heat load in the divertor and transient one by ELMs is a crucial issue for tokamak fusion devices. High radiation loss power is necessary for the heat load reduction, and the conventional gas puffing can increase the density and the radiation loss power, but it degrades the confinement. Core plasma with high confinement should be maintained simultaneously. Impurity seeding is a secure way to enhance the radiation loss power. In JT-60U, heat load is successfully reduced by Ar injection with keeping a high confinement in ELMy H-mode plasmas. In this paper, heat load reduction, radiation enhancement, and change of ELM activity are discussed.
D
) in JT-60UNakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Yagyu, Junichi; Arai, Takashi; Asakura, Nobuyuki; Itami, Kiyoshi
Journal of Nuclear Materials, 313-316(1-3), p.149 - 152, 2003/03
Times Cited Count：29 Percentile：85.65(Materials Science, Multidisciplinary)In JT-60U, boronization using hydride-decaborane (BD) was performed to reduce oxygen impurity and particle recycling. A problem of the boronization was that hydrogen originating from hydride-decaborane diluted core deuterium plasmas. In order to minimize the number of conditioning tokamak discharges, boronization using deuterated-decaborane (BD) has been introduced recently. In order to investigate durability of the boronization effects, discharges with an identical condition were repeated. Boronization using 20 g of deuterated-decaborane could reduce a core oxygen content from 
1.9% to only 1.3% in L-mode discharges with a neutral beam heating power of 4 MW. Boronization using 70 g of deuterated-decaborane reduced the core oxygen content from 2.2% to 0.5%. After the boronization using 70 g of deuterated-decaborane ( thickness of the Boron layer 135 nm ), the core oxygen content increased gradually from 0.5% to 1% in 400 shots.
Hayashi, Nobuhiko; Takizuka, Tomonori; Hosokawa, Masanari*; Shimizu, Katsuhiro
Journal of Nuclear Materials, 313-316(1-3), p.1041 - 1045, 2003/03
Times Cited Count：3 Percentile：25.79(Materials Science, Multidisciplinary)Asymmetric equilibria of divertor plasmas influenced by the thermoelectric potential and the momentum loss due to the charge-exchange have been studied by using the five-point model. The momentum loss becomes large when the divertor plasma temperature decreases below about 10 eV. The pre-sheath potential is increased by the momentum loss and compensates for the decrease in the thermoelectric potential at the low-temperature side of the asymmetric equilibrium. Through The change of the pre-sheath potential, the momentum loss has a stabilizing effect on the thermoelectric instability and mitigates the asymmetry. To lower the temperature by the recycling at the one-side divertor, the high recycling and the resultant momentum loss at the other-side divertor are effective because of the bifurcated structure of the equilibrium.
Tsuzuki, Kazuhiro; Sato, Masayasu; Kawashima, Hisato; Ogawa, Hiroaki; Kimura, Haruyuki; Okano, Fuminori; Suzuki, Sadaaki; Komata, Masao; Sawahata, Masayuki; Shinohara, Koji; et al.
Journal of Nuclear Materials, 313-316, p.177 - 181, 2003/03
Times Cited Count：9 Percentile：53.35(Materials Science, Multidisciplinary)no abstracts in English
Taniguchi, Masaki; Sato, Kazuyoshi; Ezato, Koichiro; Yokoyama, Kenji; Dairaku, Masayuki; Akiba, Masato
Journal of Nuclear Materials, 313-316(1-3), p.360 - 363, 2003/03
Times Cited Count：10 Percentile：56.43(Materials Science, Multidisciplinary)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.
Oya, Yasuhisa*; Hirohata, Yuko*; Morimoto, Yasutomi*; Yoshida, Hajime*; Kodama, Hiroshi*; Kizu, Kaname; Yagyu, Junichi; Goto, Yoshitaka*; Masaki, Kei; Okuno, Kenji*; et al.
Journal of Nuclear Materials, 313-316, p.209 - 213, 2003/03
Times Cited Count：25 Percentile：82.89(Materials Science, Multidisciplinary)no abstracts in English
Goto, Yoshitaka*; Yagyu, Junichi; Masaki, Kei; Kizu, Kaname; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Tanabe, Tetsuo*; Miya, Naoyuki
Journal of Nuclear Materials, 313-316, p.370 - 376, 2003/03
Times Cited Count：46 Percentile：92.95(Materials Science, Multidisciplinary)Erosion and re-deposition were studied for graphite tiles from W-shaped divertor region of JT-60U in Jun. 1997 - Oct. 1998 periods in which more than 3000 D-D discharges were made with all-carbon wall with boronizations and inner-private flux pumping. On the outer divertor targets, erosion was dominant: maximum erosion depth of around 20 micrometers was measured, while on the inner targets, re-deposition was dominant: columnar structure layers and laminar/columnar-layered structures of maximum thickness around 60 micrometers were found. Through XPS analysis, compositions of the re-deposition layers at a around mid point on the inner target were 94 - 95 at% C, 3 - 4 at% B, and less than 0.6 at% O, Fe, Cr, and Ni. Boron is mainly bound to Carbon. No continuous deposition layers on the dome top/outer wing, while deposition layers were found on the inner wing. Observed in/out asymmetry is attributable to in/out asymmetry of plasma particle conditions in the divertor region.
Asakura, Nobuyuki; Sakurai, Shinji; Itami, Kiyoshi; Naito, Osamu; Takenaga, Hidenobu; Higashijima, Satoru; Koide, Yoshihiko; Sakamoto, Yoshiteru; Kubo, Hirotaka; Porter, G. D.*
Journal of Nuclear Materials, 313-316, p.820 - 827, 2003/03
Times Cited Count：36 Percentile：89.58(Materials Science, Multidisciplinary)no abstracts in English
Kawashima, Hisato; Sengoku, Seio; Tsuzuki, Kazuhiro; Ogawa, Hiroaki; Kimura, Haruyuki
Journal of Nuclear Materials, 313-316, p.1338 - 1342, 2003/03
Times Cited Count：3 Percentile：25.79(Materials Science, Multidisciplinary)no abstracts in English
Loarte, A.*; Saibene, G.*; Sartori, R.*; Becoulet, M.*; Horton, L.*; Eich, T.*; Herrmann, A.*; Laux, M.*; Matthews, G.*; Jachmich, S.*; et al.
Journal of Nuclear Materials, 313-316, p.962 - 966, 2003/03
Times Cited Count：114 Percentile：98.43(Materials Science, Multidisciplinary)no abstracts in English
