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Journal Articles

Experimental progress on zonal flow physics in toroidal plasmas

Fujisawa, Akihide*; Ido, Takeshi*; Shimizu, Akihiro*; Okamura, Shoichi*; Matsuoka, Keisuke*; Iguchi, Harukazu*; Hamada, Yasuji*; Nakano, Haruhisa*; Oshima, Shinsuke*; Ito, Kimitaka*; et al.

Nuclear Fusion, 47(10), p.S718 - S726, 2007/10

 Times Cited Count:90 Percentile:95.56(Physics, Fluids & Plasmas)

Present status of experiments on zonal flows is overviewed. Innovative use of modern diagnostics has revealed the existence of zonal flows, their spatio-temporal characteristics, their relationship with turbulence, and their effects on confinement. Particularly a number of observations have been accumulated on the oscillatory branch of the zonal flow, dubbed as geodesic acoustic modes suggesting necessity of theories to give their proper description. Several new methods have elucidated the zonal flow generation processes from the turbulence. Further investigation of relationship between the zonal flows and confinement is strongly encouraged as cross-device activity.

Journal Articles

Measurement and analysis of the fluctuations and poloidal flow on JFT-2M tokamak

Hoshino, Katsumichi; Ido, Takeshi*; Nagashima, Yoshihiko*; Shinohara, Koji; Ogawa, Hiroaki; Kamiya, Kensaku; Kawashima, Hisato; Tsuzuki, Kazuhiro*; Kusama, Yoshinori; Oasa, Kazumi; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

We report on the potential/density fluctuations in the JFT-2M tokamak. We identified a geodesic acoustic mode (GAM) and its electric field structure. The GAM interacts with the background turbulence in consistent with a drift wave - zonal flow theory. The GAM modulates the turbulence, and the suppression depends on the direction and gradient of the flow velocity in consistent with a theory. During the H-mode, the GAM disappears presumably due to the suppression of the turbulence. We analysed the low frequency potential oscillation during the H-mode. A wavelet analysis showed a low frequency characteristic potential fluctuations (several handred kHz), which disappears in the L-mode and at the occurence of ELM. Observed poloidal flow is about 20 times as large as that of the GAM during the H-mode. If the potential has a spatial inhomogineity, there is a possibility that this low frequency fluctuation comes from the EXB flow or the zonal flow.

Journal Articles

Experimental progress on zonal flow physics in toroidal plasmas

Fujisawa, Akihide*; Ido, Takeshi*; Shimizu, Akihiro*; Okamura, Shoichi*; Matsuoka, Keisuke*; Hamada, Yasuji*; Hoshino, Katsumichi; Nagashima, Yoshihiko*; Shinohara, Koji; Nakano, Haruhisa*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03

Present status of experiments on zonal flows is overviewed. Innovative use of traditional and modern diagnostics has revealed unambiguously the existense of the zonal flows, their spatio-temporal caracteristics, their relationship with turbulence, and their effects on confinement. Particularly, a number of observations have been accumulated on the oscillatory branch of zonal flows, dubbed geodesic acoustic modes, suggesting necessity of theories to give their proper description. Furthur investigation of relationship between zonal flows and confinement is strongly encouraged as cross-device activity.

Journal Articles

Compatibility of reduced activation ferritic steel wall with high performance plasma on JFT-2M

Tsuzuki, Kazuhiro; Kamiya, Kensaku; Shinohara, Koji; Bakhtiari, M.*; Ogawa, Hiroaki; Kurita, Genichi; Takechi, Manabu; Kasai, Satoshi; Sato, Masayasu; Kawashima, Hisato; et al.

Nuclear Fusion, 46(11), p.966 - 971, 2006/11

 Times Cited Count:16 Percentile:51.14(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Observation of the interaction between the geodesic acoustic mode and ambient fluctuation in the JFT-2M tokamak

Ido, Takeshi*; Miura, Yukitoshi; Hoshino, Katsumichi; Kamiya, Kensaku; Hamada, Yasuji*; Nishizawa, Akimitsu*; Kawasumi, Yoshiaki*; Ogawa, Hiroaki; Nagashima, Yoshihiko*; Shinohara, Koji; et al.

Nuclear Fusion, 46(5), p.512 - 520, 2006/05

 Times Cited Count:80 Percentile:93.3(Physics, Fluids & Plasmas)

The electrostatic fluctuation spectrum and the fluctuation-induced particle flux of the JFT-2M tokamak were estimated using the hevy ion beam probe (HIBP) measurement. A geodesic acoustic mode (GAM) of the frequency about15kHz was identified in the L-mode. The GAM has its peak at about 3cm inside of the separatrix with the electric field of about 1.4kV/m. The estimated turbulent particle flux is found to be intermittent. It is found that the density fluctuation is modulated by the GAM in the wide frequency range and the coherence analysis shows that the flucruation-induced particle flux is partially contributed by the GAM. In the H-mode the GAM disappears and the fluctuation and the flux is much decreased.The mechanism of the large burst-like flux in the L-mode is not understood yet and left as the future problem.

Journal Articles

Geodesic-acoustic-mode in JFT-2M tokamak plasmas

Ido, Takeshi*; Miura, Yukitoshi; Kamiya, Kensaku; Hamada, Yasuji*; Hoshino, Katsumichi; Fujisawa, Akihide*; Ito, Kimitaka*; Ito, Sanae*; Nishizawa, Akimitsu*; Ogawa, Hiroaki; et al.

Plasma Physics and Controlled Fusion, 48(4), p.S41 - S50, 2006/04

 Times Cited Count:119 Percentile:96.8(Physics, Fluids & Plasmas)

The potential and density fluctuations of Geodesic-Acoustic-Mode (GAM) were investigated through the direct and simultaneous measurement of electrostatic and density fluctuations with a heavy ion beam probe(HIBP). It was found that the amplitude of the fluctuation has a maximum inside of the plasma boundary and that it has an almost constant frequency. It was also found that the mode propagates in the radial direction and that the GAM affects the background turbulence. The influence to the background turbulence was found to be in consistent with a theoretical prediction.

Journal Articles

Plasma diagnostics in JFT-2M

Kasai, Satoshi*; Kamiya, Kensaku; Shinohara, Koji; Kawashima, Hisato; Ogawa, Hiroaki; Uehara, Kazuya; Miura, Yukitoshi; Okano, Fuminori; Suzuki, Sadaaki; Hoshino, Katsumichi; et al.

Fusion Science and Technology, 49(2), p.225 - 240, 2006/02

 Times Cited Count:3 Percentile:25.6(Nuclear Science & Technology)

The diagnostic system of JFT-2M has consisted of about 30 individual diagnostic instruments,which were used to study the plasma production, control, equilibrium, stability, confinement, plasma heating by NBI and/or RF (LH, ICRF, ECH) and current drive by RF. In these instruments, the motional Stark effect (MSE) polarimeter, charge exchanged recombination spectroscopy (CXRS), heavy-ion beam probe (HIBP), time of flight (TOF) neutral particle analyzer, etc. have contributed to make clear the improved mechanism of confinement such as H-mode and High Recycling Steady (HRS) H-mode, and to search the operational region of these modes.The infrared TV camera system and lost ion probe have played a very important role to investigate the heat load onto the walls due to ripple loss particles and escaping ions from core plasma, respectively.

Journal Articles

Characteristics of plasma operation with the ferritic inside wall and its compatibility with high-performance plasmas in JFT-2M

Tsuzuki, Kazuhiro*; Kimura, Haruyuki; Kusama, Yoshinori; Sato, Masayasu; Kawashima, Hisato; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Uehara, Kazuya; Kurita, Genichi; et al.

Fusion Science and Technology, 49(2), p.197 - 208, 2006/02

 Times Cited Count:11 Percentile:63.08(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Zonal flow study with heavy ion beam probes, 2

Ido, Takeshi*; Hamada, Yasuji*; Miura, Yukitoshi; Hoshino, Katsumichi

Purazuma, Kaku Yugo Gakkai-Shi, 81(2), p.987 - 992, 2005/12

The heavy ion beam probe(HIBP) is a powerfull tool to investigate the potential and density fluctuation in high temperature plasmas, and in these days, the study of the zonal flow pregresses rapidly using the HIBP. In this article, the characteristic of the Geodesic Acoustic Mode(GAM) which is a kind of the zonal flow is introduced on the basis of the observation in the JIPPT-IIU tokamak and in the JFT-2M tokamak. The observed frequency and the space structure of the mode are quite similar to the theoretical prediction. An influence of the the GAM flow on the background fluctuation is also observed.

Journal Articles

High performance tokamak experiments with a ferritic steel wall on JFT-2M

Tsuzuki, Kazuhiro; Kimura, Haruyuki; Kawashima, Hisato; Sato, Masayasu; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Hoshino, Katsumichi; Bakhtiari, M.; Kasai, Satoshi; et al.

Nuclear Fusion, 43(10), p.1288 - 1293, 2003/10

 Times Cited Count:39 Percentile:76.12(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Calibration of heavy ion beam probe energy analyzer using mesh probe in the JFT-2M tokamak

Kamiya, Kensaku; Miura, Yukitoshi; Ido, Takeshi*; Hamada, Yasuji*

Review of Scientific Instruments, 74(9), p.4206 - 4208, 2003/09

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Relations among potential change, fluctuation change and transport barrier in the JFT-2M tokamak

Miura, Yukitoshi; Ido, Takeshi*; Kamiya, Kensaku; Hamada, Yasuji*; JFT-2M Group

Nuclear Fusion, 41(8), p.973 - 979, 2001/08

 Times Cited Count:16 Percentile:49.25(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Development of mesh probe for the calibration of the HIBP diagnostic system in the JFT-2M tokamak

Kamiya, Kensaku; Miura, Yukitoshi; Tsuzuki, Kazuhiro; Ido, Takeshi*; Hamada, Yasuji*; Nakayama, Takeshi*

Review of Scientific Instruments, 72(1), p.579 - 582, 2001/01

 Times Cited Count:2 Percentile:20.74(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Temporal behaviour of the potential and fluctuations at the L/H transition on JFT-2M

Ido, Tsuyoshi; Kamiya, Kensaku; Miura, Yukitoshi; Hamada, Yasuji*; Nishizawa, Akimitsu*; Kawasumi, Yoshiaki*

Plasma Physics and Controlled Fusion, 42(5A), p.A309 - A315, 2000/05

 Times Cited Count:17 Percentile:49.56(Physics, Fluids & Plasmas)

no abstracts in English

Oral presentation

Development of human resources for research and development to support nuclear energy utilization

Kugo, Teruhiko; Hamada, Jumpei; Mineo, Hideaki; Okubo, Nariaki; Takano, Masahide; Matsumura, Tatsuro; Watanabe, Masayuki; Iwamoto, Osamu; Morita, Yasuji; Maekawa, Fujio

no journal, , 

The status of development of human resources in JAEA for research and development to support nuclear energy utilization is reported.

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