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Kojima, Atsushi; Umeda, Naotaka; Hanada, Masaya; Yoshida, Masafumi; Kashiwagi, Mieko; Tobari, Hiroyuki; Watanabe, Kazuhiro; Akino, Noboru; Komata, Masao; Mogaki, Kazuhiko; et al.
Nuclear Fusion, 55(6), p.063006_1 - 063006_9, 2015/06
Times Cited Count：41 Percentile：89.69(Physics, Fluids & Plasmas)Significant progresses in the extension of pulse durations of powerful negative ion beams have been made to realize the neutral beam injectors for JT-60SA and ITER. In order to overcome common issues of the long pulse production/acceleration of negative ion beams in JT-60SA and ITER, the new technologies have been developed in the JT-60SA ion source and the MeV accelerator in Japan Atomic Energy Agency. As for the long pulse production of high-current negative ions for JT-60SA ion source, the pulse durations have been successfully increased from 30 s at 13 A on JT-60U to 100 s at 15 A by modifying the JT-60SA ion source, which satisfies the required pulse duration of 100 s and 70% of the rated beam current for JT-60SA. This progress was based on the R&D efforts for the temperature control of the plasma grid and uniform negative ion productions with the modified tent-shaped filter field configuration. Moreover, the each parameter of the required beam energy, current and pulse has been achieved individually by these R&D efforts. The developed techniques are useful to design the ITER ion source because the sustainment of the cesium coverage in large extraction area is one of the common issues between JT-60SA and ITER. As for the long pulse acceleration of high power density beams in the MeV accelerator for ITER, the pulse duration of MeV-class negative ion beams has been extended by more than 2 orders of magnitude by modifying the extraction grid with a high cooling capability and a high-transmission of negative ions. A long pulse acceleration of 60 s has been achieved at 70 MW/m
(683 keV, 100 A/m) which has reached to the power density of JT-60SA level of 65 MW/m.
Takenaga, Hidenobu; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Konoshima, Shigeru; Shimizu, Katsuhiro; Tsuzuki, Kazuhiro; Masaki, Kei; Tanabe, Tetsuo*; Ide, Shunsuke; et al.
Nuclear Fusion, 46(3), p.S39 - S48, 2006/03
Times Cited Count：18 Percentile：52.36(Physics, Fluids & Plasmas)no abstracts in English
Kusama, Yoshinori
Purazuma Shindan No Kiso To Oyo, p.195 - 205, 2006/03
no abstracts in English
Ishikawa, Masao; Takechi, Manabu; Shinohara, Koji; Kusama, Yoshinori; Cheng, C. Z.*; Matsunaga, Go; Todo, Yasushi*; Gorelenkov, N. N.*; Kramer, G. J.*; Nazikian, R. M.*; et al.
Nuclear Fusion, 45(12), p.1474 - 1480, 2005/12
Times Cited Count：38 Percentile：74.86(Physics, Fluids & Plasmas)To investigate energetic ion transport induced by Alfven eigenmodes (AEs) the neutron emission profile measurement and the charge exchange (CX) neutral particle flux measurement by Natural Diamond Detector has been performed simultaneously in the JT-60U for the first time. The energetic ion profiles inferred from these measurements indicate that ALEs cause a radial redistribution of energetic ions of limited energy range from the core region to the outer region of the plasma in weak shear plasmas. This energy range is consistent with the resonance condition between the mode and the energetic ions. In reversed shear plasmas, reversed-shear-induced AEs (RSAEs) and their transition to TAEs as the minimum value of the safety factor decreases has been observed. Neutron measurements suggest energetic ion loss is large in the transition phase from RSAEs to TAEs.
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
Okano, Kunihiko*; Suzuki, Takahiro; Umeda, Naotaka; Hiwatari, Ryoji*; Masaki, Kei; Tobita, Kenji; Fujita, Takaaki
Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.579 - 580, 2005/08
In a toroidal system, circulating fast ions generated by neutral beam injection affect the beam stopping cross-section of the neutral beam itself. This effect is called "beam particle self-interaction (BPSI)". In a recent experiment in JT-60U with 350 keV H
beam, an indication of this BPSI effect has been found for the first time. In a low density discharge at about 1
10
m
, the beam shine-through decreased by about 35% within several hundred msec after beam injection. This result is consistent with a prediction by the BPSI theory.
Kusama, Yoshinori; Ishikawa, Masao
NEW DIAMOND, 21(3), p.24 - 25, 2005/07
no abstracts in English
n eigenmodes driven by negative-ion-based neutral beams in JT-60UShinohara, Koji; Ishikawa, Masao; Takechi, Manabu; Kusama, Yoshinori; Todo, Yasushi*; Gorelenkov, N. N.*; Cheng, C. Z.*; Fukuyama, Atsushi*; Kramer, G.*; Nazikian, R. M.*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 81(7), p.547 - 552, 2005/07
In the bursting instabilities in the frequency range of Alfven Eigenmode, we observed two types of modes phenomenologically. In one type, the time scale of the mode was 
1ms and the mode amplitude was so large that we were able to detect apparent enhanced transport of the energetic ions. The enhanced transport showed the clear energy dependence by using new diagnostics, natural diamond detector. In another type, the mode amplitude is not so large, compared with the first type. The frequency up-down chirping is clearly observed with the time-scale of a few ms. This frequency chirping was reproduced by the newly developed simulation code, MEGA To demonstrate this model of Reversed-Shear-induced Alfven Eigenmode, RSAE, we have performed experiments in the condition where we can have q profile with a good signal-to-noise ratio. We observed the slow up-frequency sweeping of RSAE due to the down evolution of qmin, We have analyzed this experiment by using NOVA-K code. We observed that the most unstable mode localized around qmin.
Takenaga, Hidenobu; Asakura, Nobuyuki; Higashijima, Satoru; Nakano, Tomohide; Kubo, Hirotaka; Konoshima, Shigeru; Oyama, Naoyuki; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki; et al.
Journal of Nuclear Materials, 337-339, p.802 - 807, 2005/03
Times Cited Count：14 Percentile：67.75(Materials Science, Multidisciplinary)no abstracts in English
Takenaga, Hidenobu; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Konoshima, Shigeru; Shimizu, Katsuhiro; Tsuzuki, Kazuhiro; Ide, Shunsuke; Fujita, Takaaki
Proceedings of 4th IAEA Technical Meeting on Steady-State Operation of Magnetic Fusion Devices and MHD of Advanced Scenarios (Internet), 8 Pages, 2005/02
no abstracts in English
Kusama, Yoshinori; Ishikawa, Masao; Takechi, Manabu; Nishitani, Takeo; Morioka, Atsuhiko; Sasao, Mamiko*; Isobe, Mitsutaka*; Krasilnikov, A.*; Kaschuck, Y.*
Proceedings of Plasma Science Symposium 2005/22nd Symposium on Plasma Processing (PSS-2005/SPP-22), p.395 - 396, 2005/00
The energetic neutral particles have been successfully measured with a natural diamond detector in the neutron and 
ray radiation circumstance of the JT-60U deuterium discharges. The diamond detector was covered with polyethylene and lead in order to reduce the neutron and ray background. The shield has shown expected shielding capability. A rapid increase in neutral particles has been observed at the onset of the Toroidal Alfven Eigenmode (TAE) excited by the negative-ion-based neutral beam injection. The energy range of increased neutral particles has agreed well with that predicted from the resonant interaction between the energetic ions and the TAE.
Isobe, Mitsutaka*; Shinohara, Koji
Purazuma, Kaku Yugo Gakkai-Shi, 80(12), p.1036 - 1043, 2004/12
Escaping energetic ion diagnostics in magnetically confined plasma experiments are described in this lecture note. Experimental results from escaping energetic ion diagnostics in TFTR, JFT-2M, CHS and W7-AS are shown. In addition to mechanism of energetic ion loss from a viewpoint of particle orbit, effect of MHD activity on energetic particle transport is reviewed.
Ishikawa, Masao; Kusama, Yoshinori; Takechi, Manabu; Nishitani, Takeo; Morioka, Atsuhiko; Sasao, Mamiko*; Isobe, Mitsutaka*; Krasilnikov, A.*; Kaschuck, Y. A.*
Review of Scientific Instruments, 75(10), p.3643 - 3645, 2004/10
Times Cited Count：6 Percentile：35.65(Instruments & Instrumentation)Measurement of energy distribution of charge exchange neutral particles by using Natural Diamond Detector (NDD) has been started on the JT-60U Tokamak. Because the NDD is sensitive to neutrons and -rays too, the radiation shield has been set up around the NDD. Then energy distribution of neutral particles corresponding to injected neutral beam energy are successfully obtained. Also, enhance of neutral particle flux due to sawtooth oscillation and Alfven Eigenmode induced by N-NBI was observed. The performance of the NDD as CX neutral particle analyzer under the DD neutron filed was demonstrated on JT-60U.
Sakurai, Shinji; JT-60 Team
Plasma Science and Technology, 6(1), p.2151 - 2158, 2004/02
Times Cited Count：0 Percentile：0.02(Physics, Fluids & Plasmas)no abstracts in English
Mironov, M. I.*; Khudoleev, A. V.*; Kusama, Yoshinori
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
no abstracts in English
Fukuda, Takeshi; JT-60 Team
Plasma Physics and Controlled Fusion, 44(12B), p.B39 - B52, 2002/12
Times Cited Count：7 Percentile：24.28(Physics, Fluids & Plasmas)no abstracts in English
n eigenmode experiments using N-NB in JT-60U tokamakShinohara, Koji; Takechi, Manabu; Ishikawa, Masao*; Kusama, Yoshinori; Morioka, Atsuhiko; Oyama, Naoyuki; Tobita, Kenji; Ozeki, Takahisa; JT-60 Team; Gorelenkov, N. N.*; et al.
Nuclear Fusion, 42(8), p.942 - 948, 2002/08
Times Cited Count：43 Percentile：77.26(Physics, Fluids & Plasmas)no abstracts in English
Suzuki, Takahiro; Sugie, Tatsuo
Purazuma, Kaku Yugo Gakkai-Shi, 78(5), p.411 - 416, 2002/05
no abstracts in English
Tsuchiya, Katsuhiko; Fukuda, Takeshi; Takenaga, Hidenobu; Asakura, Nobuyuki; Kamada, Yutaka; Takizuka, Tomonori; Itami, Kiyoshi; Fujita, Takaaki; JT-60 Team
Nuclear Fusion, 42(6), p.637 - 642, 2002/01
Times Cited Count：1 Percentile：0.02(Physics, Fluids & Plasmas)no abstracts in English
Takenaga, Hidenobu; Sakasai, Akira; Kubo, Hirotaka; Asakura, Nobuyuki; Schaffer, M. J.*; Petrie, T. W.*; Mahdavi, M. A.*; Baker, D. R.*; Allen, S. L.*; Porter, G. D.*; et al.
Nuclear Fusion, 41(12), p.1777 - 1787, 2001/12
Times Cited Count：22 Percentile：57.48(Physics, Fluids & Plasmas)no abstracts in English
