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Journal Articles

CIELO collaboration summary results; International evaluations of neutron reactions on uranium, plutonium, iron, oxygen and hydrogen

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Kahler, A. C.*; Talou, P.*; Plompen, A. J.*; Schillebeeckx, P.*; et al.

Nuclear Data Sheets, 148, p.189 - 213, 2018/02

 Times Cited Count:49 Percentile:98.76(Physics, Nuclear)

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - $$^{235}$$U, $$^{238}$$U, $$^{239}$$Pu, $$^{56}$$Fe, $$^{16}$$O and $$^{1}$$H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality. This report summarizes our results and outlines plans for the next phase of this collaboration.

Journal Articles

Confinement degradation and transport of energetic ions due to Alfv$'e$n eigenmodes in JT-60U weak shear plasmas

Ishikawa, Masao; Takechi, Manabu; Shinohara, Koji; Cheng, C. Z.*; Matsunaga, Go; Kusama, Yoshinori; Fukuyama, Atsushi*; Nishitani, Takeo; Morioka, Atsuhiko; Sasao, Mamiko*; et al.

Nuclear Fusion, 47(8), p.849 - 855, 2007/08

 Times Cited Count:19 Percentile:58.82(Physics, Fluids & Plasmas)

Confinement degradation of energetic ions due to Alfv$'e$n Eigenmodes (AEs) induced by negative-ion-based neutral beam injection for the classical confinement is quantitatively evaluated for the first time. AEs, whose frequency largely sweep and then saturate as the minimum value of the safety factor decrease, have been observed in JT-60U. These mode behavior can be explained by RSAEs and the transition from RSAEs to TAEs. Measured total neutron emission rate in the presence of these AEs is compared with that predicted by a classical theory. As a result, confinement degradation of energetic ions is confirmed. Line-integrated neutron emission profile is also compared with that predicted when assuming that the confinement is classical. The result indicates energetic ions are transported from core region of the plasma due to these AEs.

Journal Articles

Observation of confinement degradation of energetic ions due to Alfv$'e$n eigenmodes in JT-60U weak shear plasmas

Ishikawa, 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:13 Percentile:44.28(Physics, Fluids & Plasmas)

Confinement degradation of energetic ions due to Alfv$'e$n 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.

Journal Articles

Energetic ion transport by abrupt large-amplitude event induced by negative-ion-based neutral beam injection in the JT-60U

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:37 Percentile:76.55(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.

Journal Articles

Alfv$'e$n eigenmodes in reversed shear plasmas in JT-60U negative-ion-based neutral beam injection discharges

Takechi, 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:31 Percentile:70.18(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 Alfv$'e$n Eigenmodes (RSAEs), which are ideal MHD Alfv$'e$n eigenmodes (AEs) localized to the region of minimum safety factor, $$q_{rm min}$$, 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$'{e}$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 $$q$$$$_{min}$$, e.g., 2.4 $$<$$ $$q$$$$_{min}$$ $$<$$ 2.7 for the n = 1 AE to avoid substantial fast ion loss in RS plasmas.

Journal Articles

Instability in the frequency range of Alfv$'e$n eigenmodes driven by negative-ion-based neutral beams in JT-60U

Shinohara, 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.

Journal Articles

Energetic particle physics in JT-60U and JFT-2M

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:40 Percentile:79.05(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.

Journal Articles

Recent progress of Alfv$'e$n eigenmode experiments using N-NB in JT-60U tokamak

Shinohara, 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:39 Percentile:76.63(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Magnetic safety factor profile before and after sawtooth crashes investigated with toroidicity and ellipticity induced Alfv$'e$n eigenmodes

Kramer, 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:32 Percentile:70.38(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Alf$'e$n eigenmodes driven by Alf$'e$nic beam ions in JT-60U

Shinohara, 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:78 Percentile:90.62(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Fast particle experiments in JT-60U

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:44 Percentile:78.44(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Characteristics of Alfv$'e$n eigenmodes, burst modes and chirping modes in the Alfv$'e$n frequency range driven by negative ion based neutral beam injection in JT-60U

Kusama, 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:63 Percentile:87.19(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Frequency chirping of core-localized toroidicity-induced Alfv$'e$n eigenmodes and their coupling to global Alfv$'e$n eigenmodes

Kramer, 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:22 Percentile:74.7(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Alfv$'e$n eigenmodes and their impact on plasma characteristics in JT-60U

Kusama, Yoshinori; Nazikian, R.*; Kramer, G. J.*; Kimura, Haruyuki; Saigusa, Mikio*; Ozeki, Takahisa; Fu, G. Y.*; Tobita, Kenji; Oikawa, Toshihiro; Shinohara, Koji; et al.

Fusion Energy 1998, 2, p.537 - 544, 1998/10

no abstracts in English

Oral presentation

Observation of confinement degradation of energetic ions by Alfv$'e$n eigenemodes in weak shear plasmas on JT-60U

Ishikawa, 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 Alfv$'e$n Eigenemode model or Alfv$'e$n 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.

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