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Novello, L.*; Cara, P.*; Coletti, A.*; Gaio, E.*; Maistrello, A.*; Matsukawa, Makoto; Philipps, G.*; Tomarchio, V.*; Yamauchi, Kunihito
IEEE Transactions on Applied Superconductivity, 26(2), p.4700507_1 - 4700507_7, 2016/03
Times Cited Count:7 Percentile:39.28(Engineering, Electrical & Electronic)Sukegawa, Atsuhiko; Murakami, Haruyuki; Matsunaga, Go; Sakurai, Shinji; Takechi, Manabu; Yoshida, Kiyoshi; Ikeda, Yoshitaka
Fusion Engineering and Design, 98-99, p.2076 - 2079, 2015/10
Times Cited Count:2 Percentile:17.42(Nuclear Science & Technology)The JT-60SA project is a EU - JA satellite tokamak under Broader Approach in support of the ITER project. In-vessel coils are designed and assembled by JA. The resin-insulator is required to have a heat resistance against the baking temperature of vacuum vessel of 200C (40000 hour). Thus the assessment of the heat load is fundamental for the design of the coils. However, the estimation of the lifetime of resin-insulator under the high-temperature region has not been examined. In the present study, the estimation of the lifetime of seven candidate resin-insulators such as epoxy resin and cyanate-ester resin under the 220C temperature region have been performed for the current coils design. Weight reduction of the seven candidate insulators was measured at different heating times under 180C, 200C and 220C environment using three thermostatic ovens, respectively. The reduction of the insulators has been used as input for Weibull-analysis towards Arrhenius-plot. Lifetime of the resins has been estimated for the first time at the high temperature region by the plot. Lifetime of the resin-insulators have been evaluated and discussed as well as the available temperature of the in-vessel coils.
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)Shimizu, Yusuke*; Fujita, Takaaki*; Arimoto, Hideki*; Nakano, Tomohide; Hoshino, Kazuo; Hayashi, Nobuhiko
Plasma and Fusion Research (Internet), 10(Sp.2), p.3403062_1 - 3403062_4, 2015/07
Zito, P.*; Lampasi, A.*; Novello, L.*; Matsukawa, Makoto; Shimada, Katsuhiro; Portesine, M.*; Fasce, F.*; Cinarelli, D.*; Dorronsoro, A.*; Vian, D.*
Proceedings of IEEE 15th International Conference on Environment and Electrical Engineering (IEEE-EEEIC 2015), p.156 - 160, 2015/06
Garcia, J.*; Hayashi, Nobuhiko; Baiocchi, B.*; Giruzzi, G.*; Honda, Mitsuru; Ide, Shunsuke; Maget, P.*; Narita, Emi*; Schneider, M.*; Urano, Hajime; et al.
Nuclear Fusion, 54(9), p.093010_1 - 093010_13, 2014/09
Times Cited Count:38 Percentile:86.43(Physics, Fluids & Plasmas)Garcia, J.*; Hayashi, Nobuhiko; Giruzzi, G.*; Schneider, M.*; Joffrin, E.*; Ide, Shunsuke; Sakamoto, Yoshiteru; Suzuki, Takahiro; Urano, Hajime; JT-60 Team; et al.
Europhysics Conference Abstracts (Internet), 38F, p.P1.029_1 - P1.029_4, 2014/06
Hatae, Takaki; Naito, Osamu; Kitamura, Shigeru; Sakuma, Takeshi*; Hamano, Takashi*; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*
Journal of the Korean Physical Society, 49, p.S160 - S164, 2006/12
no abstracts in English
Ikeda, Yoshitaka; NBI Heating Group; NCT Design Team
Journal of the Korean Physical Society, 49, p.S43 - S47, 2006/12
There are two type of NBI systems on JT-60U. One is the positive ion-based NBI (P-NBI) to inject the beam energy of 80-85 kV. The other is the negative ion-based NBI (N-NBI) at the beam energy more than 350 keV. Recently the pulse duration of NBI system was required to extend up to 30 sec so as to study long pulse plasmas. The four P-NBI units, which tangentially inject neutral beam to plasma, were modified to extend the pulse duration up to 30 sec with 2 MW/unit at 85 keV. The seven P-NBI units, each of which perpendicularly injects for 10 sec, were conducted to operate in series for the total pulse duration of 30 sec. The ion source of the N-NBI unit was also modified to reduce the heat load of the grid for 30 sec operation. The pulse duration was extended up to 25 sec, 1 MW at the beam energy of 350keV. In the next step, further pulse extension of NBI up to 100 sec is planned for the modified JT-60U with superconducting coils (so called NCT). This paper reports the recent progress of the NBI system on JT-60U and the design study of the upgraded NBI system for NCT.
Urano, Hajime; Takizuka, Tomonori; Takenaga, Hidenobu; Oyama, Naoyuki; Miura, Yukitoshi; Kamada, Yutaka
Nuclear Fusion, 46(8), p.781 - 787, 2006/08
Times Cited Count:23 Percentile:60.06(Physics, Fluids & Plasmas)The degradation of energy confinement with increased toroidal beta was shown by the non-dimensional analysis in JT-60U. The dependence of the energy confinement on was examined by both the JT-60U ELMy -mode confinement database and the dedicated experiment on a single scan while and were kept fixed as well as the other magnetic geometrical parameters. In both cases, the degradation of energy confinement with increasing was observed, satisfying the relation of . This dependence is a little weaker than that predicted by the IPB98(y,2) scaling. The fusion power production rate was estimated to increase in proportion to .
Sakata, Shinya; Totsuka, Toshiyuki; Kiyono, Kimihiro; Oshima, Takayuki; Sato, Minoru; Ozeki, Takahisa
Fusion Engineering and Design, 81(15-17), p.1775 - 1778, 2006/07
Times Cited Count:9 Percentile:53.28(Nuclear Science & Technology)no abstracts in English
Ikeda, Yoshitaka; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kawai, Mikito; Kazawa, Minoru; et al.
Nuclear Fusion, 46(6), p.S211 - S219, 2006/06
Times Cited Count:59 Percentile:87.04(Physics, Fluids & Plasmas)Recently, the extension of the pulse duration up to 30 sec has been intended to study quasi-steady state plasma on JT-60U N-NBI system. The most serious issue is to reduce the heat load on the grids for long pulse operation. Two modifications have been proposed to reduce the heat load. One is to suppress the beam spread which may be caused by beamlet-beamlet interaction in the multi-aperture grid due to the space charge force. Thin plates were attached on the extraction grid to modify the local electric field. The plate thickness was optimized to steer the beamlet deflection. The other is to reduce the stripping loss, where the electron of the negative ion beam is stripped and accelerated in the ion source and then collides with the grids. The ion source was modified to reduce the pressure in the accelerator column to suppress the beam-ion stripping loss. Up to now, long pulse injection of 17 sec for 1.6 MW and 25 sec for 1 MW has been obtained by one ion source with these modifications.
Ishimoto, Yuki; Goto, Yoshitaka*; Arai, Takashi; Masaki, Kei; Miya, Naoyuki; Oyama, Naoyuki; Asakura, Nobuyuki
Journal of Nuclear Materials, 350(3), p.301 - 309, 2006/05
Times Cited Count:21 Percentile:79.93(Materials Science, Multidisciplinary)Thermal properties of the redeposition layer on the inner plate of the W-shaped divertor of JT-60U have been measured with laser flash method for the first time so as to estimate transient heat loads onto the divertor. Measurement of a redeposition layer sample of more than 200 m thick showed following results: (1) the bulk density of the redeposition layer is about half of that of carbon fiber composite material; (2) the specific heat of the layer is roughly equal to that of the isotropic graphite; (3) the thermal conductivity of the redeposition layer is two orders of magnitude smaller than that of the carbon fiber composite. The difference between the divertor heat loads and the loss of the plasma stored energy becomes smaller taking account of thermal properties of the redeposition layer on the inner divertor, whereas estimated heat loads due to the ELMs is still larger than the loss. This is probably caused by the poloidal distribution of the thermal properties and heat flux asymmetry inherent in the device.
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:21 Percentile:57.01(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.
Sakamoto, Yoshiteru; Ide, Shunsuke; Yoshida, Maiko; Koide, Yoshihiko; Fujita, Takaaki; Takenaga, Hidenobu; Kamada, Yutaka
Plasma Physics and Controlled Fusion, 48(5A), p.A63 - A70, 2006/05
Times Cited Count:34 Percentile:73.38(Physics, Fluids & Plasmas)no abstracts in English
Hayashi, Nobuhiko; Takizuka, Tomonori; Sakamoto, Yoshiteru; Fujita, Takaaki; Kamada, Yutaka; Ide, Shunsuke; Koide, Yoshihiko
Plasma Physics and Controlled Fusion, 48(5A), p.A55 - A61, 2006/05
Times Cited Count:7 Percentile:24.57(Physics, Fluids & Plasmas)no abstracts in English
Kamiya, Kensaku; Urano, Hajime; Koide, Yoshihiko; Takizuka, Tomonori; Oyama, Naoyuki; Kamada, Yutaka; JT-60 Team
Plasma Physics and Controlled Fusion, 48(5A), p.A131 - A139, 2006/05
Times Cited Count:22 Percentile:58.55(Physics, Fluids & Plasmas)Effects of plasma rotation and ripple loss on the Type-I ELMs have systematically studied in the JT-60U tokamak, scanning combinations of NBI at the three kinds of plasma volumes. New findings on the Type-I ELMs confirm to be smaller ELM energy loss per pedestal stored energy, DWELM/Wped, and faster ELM frequency, fELM, in the counter-NBI than co-NBI, keeping the power of ELM, PELM, per heating power crossing the separatrix, PSEP, constant. Balanced-NBI case is also intermediate between co- and counter-NBI. In addition, the product of PELM/PSEP decreases according to increase in the plasma volume, suggesting an increase in the inter-ELM transport due mainly to an enhancement in the ripple loss of fast ion.
Urano, Hajime; Kamiya, Kensaku; Koide, Yoshihiko; Takizuka, Tomonori; Oyama, Naoyuki; Kamada, Yutaka; JT-60 Team
Plasma Physics and Controlled Fusion, 48(5A), p.A193 - A199, 2006/05
Times Cited Count:10 Percentile:34.06(Physics, Fluids & Plasmas)The characteristics of the H-mode pedestal structure were investigated by conducting the power scans for a variation of the toroidal momentum sources at different toroidal field ripple in JT-60U. It was found that the pedestal pressure is increased by reduced loss power of fast ions, independently of toroidal rotation. However, the energy confinement is improved with the CO-directed toroidal momentum source at H-mode plasmas with small ripple loss.
La Haye, R. J.*; Prater, R.*; Buttery, R. J.*; Hayashi, Nobuhiko; Isayama, Akihiko; Maraschek, M. E.*; Urso, L.*; Zohm, H.*
Nuclear Fusion, 46(4), p.451 - 461, 2006/04
Times Cited Count:151 Percentile:97.52(Physics, Fluids & Plasmas)no abstracts in English
Takeishi, Toshiharu*; Katayama, Kazunari*; Nishikawa, Masabumi*; Masaki, Kei; Miya, Naoyuki
Journal of Nuclear Materials, 349(3), p.327 - 338, 2006/03
Times Cited Count:6 Percentile:41.26(Materials Science, Multidisciplinary)no abstracts in English