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Schaffer, M. J.*; Snipes, J. A.*; Gohil, P.*; de Vries, P.*; Evans, T. E.*; Fenstermacher, M. E.*; Gao, X.*; Garofalo, A. M.*; Gates, D. A.*; Greenfield, C. M.*; et al.
Nuclear Fusion, 51(10), p.103028_1 - 103028_11, 2011/10
Times Cited Count：35 Percentile：80.59(Physics, Fluids & Plasmas)Experiments at DIII-D investigated the effects of ferromagnetic error fields similar to those expected from proposed ITER Test Blanket Modules (TBMs). Studied were effects on: plasma rotation and locking; confinement; L-H transition; edge localized mode (ELM) suppression by resonant magnetic perturbations; ELMs and the H-mode pedestal; energetic particle losses; and more. The experiments used a 3-coil mock-up of 2 magnetized ITER TBMs in one ITER equatorial port. The experiments did not reveal any effect likely to preclude ITER operations with a TBM-like error field. The largest effect was slowed plasma toroidal rotation v across the entire radial profile by as much as 
via non-resonant braking. Changes to global 
, 
and 
were 
3 times smaller. These effects are stronger at higher 
and lower 
. Other effects were smaller.
Fasoli, A.*; Gormezano, C.*; Berk, H. L.*; Breizman, B.*; Briguglio, S.*; Darrow, D. S.*; Gorelenkov, N.*; Heidbrink, W. W.*; Jaun, A.*; Konovalov, S. V.*; et al.
Nuclear Fusion, 47(6), p.S264 - S284, 2007/06
Times Cited Count：456 Percentile：85.96(Physics, Fluids & Plasmas)no abstracts in English
n eigenmodes in JT-60U weak shear plasmasIshikawa, Masao; Takechi, Manabu; Shinohara, Koji; Kusama, Yoshinori; Matsunaga, Go; Krasilnikov, V. A.*; Kashuck, Y.*; Isobe, Mitsutaka*; Nishitani, Takeo; Sukegawa, Atsuhiko; et al.
Nuclear Fusion, 46(10), p.S898 - S903, 2006/10
Times Cited Count：16 Percentile：48.35(Physics, Fluids & Plasmas)Confinement degradation of energetic ions due to Alfvn eigenmodes (AEs) has been investigated with negative ion based neutral beam injection into JT-60U weak shear plasmas. AEs with a rapid frequency sweeping and then saturation as the minimum value of the safety factor decreases have been observed. This frequency behaviour can be explained by RSAE and the transition from RSAEs toTAEs. The associated change in the charge exchange neutral particle flux suggests energetic ion transport due to these AEs. The total neutron emission reduction rate in the presence of these AEs is evaluated by calculation using the orbit following Monte-Carlo code taking into account the change in bulk plasmas. The evaluation indicates confinement of energetic ions is degraded due to these AEs. In particular, it is found that the confinement degradation of energetic ions is maximum during the transition from RSAEs to TAEs.
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：74.93(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.
n eigenmodes in reversed shear plasmas in JT-60U negative-ion-based neutral beam injection dischargesTakechi, Manabu; Fukuyama, Atsushi*; Ishikawa, Masao; Cheng, C. Z.*; Shinohara, Koji; Ozeki, Takahisa; Kusama, Yoshinori; Takeji, Satoru*; Fujita, Takaaki; Oikawa, Toshihiro; et al.
Physics of Plasmas, 12(8), p.082509_1 - 082509_7, 2005/08
Times Cited Count：34 Percentile：71.2(Physics, Fluids & Plasmas)Rapid frequency sweeping modes observed in reversed magnetic shear (RS) plasmas on the Japan Atomic Energy Research Institute Tokamak 60 Upgrade (JT-60U) have been identified as Reversed-Shear-induced Alfvn Eigenmodes (RSAEs), which are ideal MHD Alfvn eigenmodes (AEs) localized to the region of minimum safety factor, 
, and are excited by negative-ion-based neutral beam injection. The chirping and subsequent saturation of the mode frequency are consistent with theoretical predictions for the transition from RSAEs to Toroidal Alfv
n eigenmodes (TAEs). The previously observed rapid frequency sweeping modes in ion cyclotron wave heated plasmas in JT-60U can also be similarly explained. The observed AE amplitude is largest during the transition from RSAEs to TAEs, and fast ion loss is observed when the AE amplitude is largest at this transition. It is preferable to operate outside the transition range of 
, e.g., 2.4 
2.7 for the n = 1 AE to avoid substantial fast ion loss in RS plasmas.
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.
Shinohara, Koji; Takechi, Manabu; Ishikawa, Masao; Kusama, Yoshinori; Tsuzuki, Kazuhiro; Urata, Kazuhiro*; Kawashima, Hisato; Tobita, Kenji; Fukuyama, Atsushi*; Cheng, C. Z.*; et al.
Plasma Physics and Controlled Fusion, 46(7), p.S31 - S45, 2004/07
Times Cited Count：42 Percentile：77.89(Physics, Fluids & Plasmas)Recent energetic particle physics research has been devoted to Alfven eigenmodes (AEs) in reversed-shear (RS) plasmas, energetic ion transport in the appearance of modes in the frequency range of TAE, energetic ion behavior in the plasma with a current hole, and ripple loss in the complex toroidal field ripple due to ferritic steel plates. We will report these recent progresses for energetic particle physics in JT-60U and JFT-2M.
Takenaga, Hidenobu; Higashijima, Satoru; Oyama, Naoyuki; Bruskin, L. G.; Koide, Yoshihiko; Ide, Shunsuke; Shirai, Hiroshi; Sakamoto, Yoshiteru; Suzuki, Takahiro; Hill, K. W.*; et al.
Nuclear Fusion, 43(10), p.1235 - 1245, 2003/10
Times Cited Count：71 Percentile：88.64(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：77.34(Physics, Fluids & Plasmas)no abstracts in English
Rewoldt, G.*; Hill, K. W.*; Nazikian, R. M.*; Tang, W. M.*; Shirai, Hiroshi; Sakamoto, Yoshiteru; Kishimoto, Yasuaki; Ide, Shunsuke; Fujita, Takaaki
Nuclear Fusion, 42(4), p.403 - 411, 2002/04
Times Cited Count：9 Percentile：30.39(Physics, Fluids & Plasmas)One class of internal transport barrier discharge in the JT-60U tokamak is characterized by two relatively flat regions of the pressure separated by a region with very large pressure gradient. Linear growth rates for toroidal drift type modes are calculated for discharges in this class, without and with sheared 
rotation effects. For cases with fully developed barriers, the results with rotation are consistent with a picture in which the radial electric field generated in part by the steep pressure gradient causes local stabilization, and thus reduction of the local anomalous transport, which allows the steep pressure gradient to persist. If rotation is omitted from the calculation for these cases, or if rotation is included for cases without barriers or with partially developed barriers, the unstable region spreads into the steep pressure gradient region.
Miura, Yukitoshi; Fujita, Takaaki; Oikawa, Toshihiro; Suzuki, Takahiro; Ide, Shunsuke; Sakamoto, Yoshiteru; Koide, Yoshihiko; Hatae, Takaki; Naito, Osamu; Isayama, Akihiko; et al.
IAEA-CN-94/EX/C3-1Ra (CD-ROM), 5 Pages, 2002/00
no abstracts in English
n eigenmodesKramer, G. J.; Cheng, C. Z.*; Kusama, Yoshinori; Nazikian, R. M.*; Takeji, Satoru; Tobita, Kenji
Nuclear Fusion, 41(9), p.1135 - 1151, 2001/09
Times Cited Count：37 Percentile：72.57(Physics, Fluids & Plasmas)no abstracts in English
n eigenmodes driven by Alfnic beam ions in JT-60UShinohara, Koji; Kusama, Yoshinori; Takechi, Manabu; Morioka, Atsuhiko; Ishikawa, Masao*; Oyama, Naoyuki; Tobita, Kenji; Ozeki, Takahisa; Takeji, Satoru; Moriyama, Shinichi; et al.
Nuclear Fusion, 41(5), p.603 - 612, 2001/05
Times Cited Count：83 Percentile：90.44(Physics, Fluids & Plasmas)no abstracts in English
Kramer, G. J.; Iwase, Makoto; Kusama, Yoshinori; Morioka, Atsuhiko; Nemoto, Masahiro; Nishitani, Takeo; Shinohara, Koji; Takeji, Satoru; Tobita, Kenji; Ozeki, Takahisa; et al.
Nuclear Fusion, 40(7), p.1383 - 1396, 2000/07
Times Cited Count：46 Percentile：77.78(Physics, Fluids & Plasmas)no abstracts in English
n eigenmodes, burst modes and chirping modes in the Alfvn frequency range driven by negative ion based neutral beam injection in JT-60UKusama, Yoshinori; Kramer, G. J.; Kimura, Haruyuki; Saigusa, Mikio*; Ozeki, Takahisa; Tobita, Kenji; Oikawa, Toshihiro; Shinohara, Koji; Kondoh, Takashi; Moriyama, Shinichi; et al.
Nuclear Fusion, 39(11Y), p.1837 - 1843, 1999/11
Times Cited Count：68 Percentile：87.07(Physics, Fluids & Plasmas)no abstracts in English
n eigenmodes and their coupling to global Alfvn eigenmodesKramer, G. J.; Cheng, C. Z.*; Fu, G. Y.*; Kusama, Yoshinori; Nazikian, R. M.*; Ozeki, Takahisa; Tobita, Kenji
Physical Review Letters, 83(15), p.2961 - 2964, 1999/10
Times Cited Count：24 Percentile：75.07(Physics, Multidisciplinary)no abstracts in English
Shinohara, Koji; Nazikian, R. M.*; Fujita, Takaaki; Yoshino, Ryuji
Review of Scientific Instruments, 70(11), p.4246 - 4250, 1999/00
Times Cited Count：31 Percentile：84.36(Instruments & Instrumentation)no abstracts in English
n eigenemodes in weak shear plasmas on JT-60UIshikawa, Masao; Shinohara, Koji; Takechi, Manabu; Matsunaga, Go; Kusama, Yoshinori; Krasilnikov, A.*; Kaschuck, Y.*; Isobe, Mitsutaka*; Nishitani, Takeo; Morioka, Atsuhiko; et al.
no journal, ,
Magnetohydrodynamics (MHD) instabilities with a frequency sweeping and then saturation of frequency as qmin decrease have been observed during Negative-ion-based Neutral Beam (NNB) injection in JT-60U Weak Shear (WS) plasmas. The frequency evolution of those MHD instabilities can be explained by Reversed-Shear-induced Alfvn Eigenemode model or Alfvn Cascade model. In recent experiments, a confinement degradation of energetic ions by such instabilities was clearly observed. In this work, we evoluate the confinement degradation of energetic ions by the instabilities usigng measurement of total neuron flux and neutron emission profile. Further, we will compare the confinement degradation by the above instabilities with that by Abrupt Large-amplitude Events (ALEs), which are bursting modes.
Snipes, J. A.*; Schaffer, M. J.*; Gohil, P.*; de Vries, P.*; Fenstermacher, M. E.*; Evans, T. E.*; Gao, X. M.*; Garofalo, A.*; Gates, D. A.*; Greenfield, C. M.*; et al.
no journal, ,
A series of experiments was performed on DIII-D to mock-up the field that will be induced in a pair of ferromagnetic Test Blanket Modules (TBMs) in ITER to determine the effects of such error fields on plasma operation and performance. A set of coils producing both poloidal and toroidal fields was placed inside a re-entrant horizontal port close to the plasma. The coils produce a localized ripple due to the toroidal field (TF) + TBM up to 5.7%, which is more than four times that expected from a pair of representative 1.3 ton TBMs in ITER. The experiments show that the reduction in the toroidal rotation is sensitive to the ripple. On the other hand, the confinement is reduced by up to 15-18% for local ripple 
3% but is hardly affected at 1.7% local ripple.
