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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:113 Percentile:2.99(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

Characterization of coherent magnetic fluctuations in JFT-2M high recycling steady high-confinement mode plasmas

Kamiya, Kensaku; Oyama, Naoyuki; Ido, Takeshi*; Bakhtiari, M.*; JFT-2M Group

Physics of Plasmas, 13(3), p.032507_1 - 032507_9, 2006/03

 Times Cited Count:11 Percentile:59.15(Physics, Fluids & Plasmas)

Accompanying the HRS H-mode transition, the coherent magnetic fluctuations in the frequency range of the order of 10-100 kHz with significant variation are seen on the magnetic probes at the vessel wall. Above all, two types of edge MHD activities, which have associated toroidal mode number of n=1 and n$$sim$$7, respectively, seem to be more important for the HRS H-mode plasmas. To investigate their interaction, bi-spectral analysis is applied for the magnetic probe data. It is found to be a powerful tool, exhibiting the phase-coupled oscillations between two types of edge MHD activities having n=1 and n$$sim$$7.

Journal Articles

Heating, current drive, and advanced plasma control in JFT-2M

Hoshino, Katsumichi; Yamamoto, Takumi; Tamai, Hiroshi; Oasa, Kazumi; Kawashima, Hisato; Miura, Yukitoshi; Ogawa, Toshihide; Shoji, Teruaki*; Shibata, Takatoshi; Kikuchi, Kazuo; et al.

Fusion Science and Technology, 49(2), p.139 - 167, 2006/02

 Times Cited Count:2 Percentile:81.1(Nuclear Science & Technology)

The main results obtained by the various heating and current drive systems, external coil system and divertor bias system are reviewed from the viewpoint of the advanced active control of the tokamak plasma. Also, the features of each system are described. The contribution of the JFT-2M in these areas are summarized.

Journal Articles

Reduced divertor heat loads, plasma shape effects, and radial electric field structures in JFT-2M HRS H-mode plasmas

Kamiya, Kensaku; Kawashima, Hisato; Ido, Takeshi*; Oyama, Naoyuki; Bakhtiari, M.*; Kasai, Satoshi; Kusama, Yoshinori; Miura, Yukitoshi; Ogawa, Hiroaki; Tsuzuki, Kazuhiro; et al.

Nuclear Fusion, 46(2), p.272 - 276, 2006/02

 Times Cited Count:3 Percentile:87.74(Physics, Fluids & Plasmas)

An attractive operational regime without any large ELMs, namely High Recycling Steady (HRS) H-mode, was found on JFT-2M during Y2000 campaign after boronization. Recent experiments have concentrated on the studies of the access conditions for the HRS regime, in terms of the pedestal parameters. The HRS regime was more likely at higher edge density and lower edge temperature, which corresponds to the normalized electron collisionality of 1 in the plasma edge region.

Journal Articles

Observation of nonlinear coupling between small-poloidal wave-number potential fluctuations and turbulent potential fluctuations in Ohmically heated plasmas in the JFT-2M tokamak

Nagashima, Yoshihiko*; Hoshino, Katsumichi; Ejiri, Akira*; Shinohara, Koji; Takase, Yuichi*; Tsuzuki, Kazuhiro; Uehara, Kazuya; Kawashima, Hisato; Ogawa, Hiroaki; Ido, Takeshi*; et al.

Physical Review Letters, 95(9), p.095002_1 - 095002_4, 2005/08

 Times Cited Count:95 Percentile:6.7(Physics, Multidisciplinary)

By a reciprocating electrostatic probe, two types of low frequency coherent electrostatic modes (about1kHz and 10-15kHz) are found,for the first time, in the edge region of ohmically heated plasmas in the JFT-2M tokamak. These modes exists in the last closed surface. The higher frequency mode has features of the geodesic acoustic mode (GAM), though the low frequency mode is not identified yet. A bispectral analysis revealed that significant nonlinear couplings (parametric modulation) between these coherent fluctuations and broadband background turbulent potential fluctuations occur. In the other words, the GAM and the back ground turbulence are modulated by the newly found low frequency electrostatic mode (further, the GAM modulates the background turbulence, also) for the first time. The newly found low frequency mode (frequency about 1kHz) is supposed to contribute to the turbulent diffusion nonlinearly.

Journal Articles

Pedestal characteristics in JFT-2M HRS H-mode plasma

Kamiya, Kensaku; Oyama, Naoyuki; Miura, Yukitoshi; Hubbard, A. E.*

Plasma Physics and Controlled Fusion, 46(11), p.1745 - 1755, 2004/11

 Times Cited Count:13 Percentile:55.96(Physics, Fluids & Plasmas)

Recent experiments in the JFT-2M tokamak have concentrated on the studies of the access condition for the H-mode operation without any large ELMs, namely High Recycling Steady (HRS) H-mode regime in terms of the pedestal parameters. The HRS regime is more likely at the higher edge density and lower edge temperature, while the ELMy H-mode having large ELMs appears at the lower edge density and higher edge temperature. It is found that the ELMy/HRS operational boundary occurs at the normalized electron collisionality of $$nu$$*$$_{e}$$$$sim$$1 in the plasma edge region, depending slightly on q$$_{95}$$. A key feature of the HRS H-mode is the presence of the coherent magnetic fluctuations in the frequency range of the order of 10-100 kHz. It is suggested that the edge MHD activities may keep an edge pressure below a certain level needed to induce a large ELM.

Journal Articles

Review of the history of experiments in the JFT-2M tokamak for 21 years

Miura, Yukitoshi; Hoshino, Katsumichi; Kusama, Yoshinori

Purazuma, Kaku Yugo Gakkai-Shi, 80(8), p.653 - 661, 2004/08

A series of experimental program on the JAERI Fusion Torus-2M (JFT-2M) was completed in March, 2004. In the experimental operation for 21 years since the first plasma on April 27, 1983, many significant results leading the fusion energy research and plasma physics have been produced in researches on high confinement mode (H-mode), heating and current drive, advanced plasma control, compatibility of low activation ferritic steel with improved confinement mode, etc. Among these results, some important results are presented.

Journal Articles

On MHD oscillations in high beta H-mode tokamak plasma in JFT-2M

Hoshino, Katsumichi; Nagashima, Yoshihiko*; Ido, Takeshi*; Tsuzuki, Kazuhiro; Kawashima, Hisato; Ogawa, Hiroaki; Bakhtiari, M.; Shinohara, Koji; Uehara, Kazuya; Oasa, Kazumi; et al.

Journal of Plasma and Fusion Research SERIES, Vol.6, p.345 - 348, 2004/00

no abstracts in English

Journal Articles

Observation of high recycling steady H-mode edge and compatibility with improved core confinement mode on JFT-2M

Kamiya, Kensaku; Kimura, Haruyuki; Ogawa, Hiroaki; Kawashima, Hisato; Tsuzuki, Kazuhiro; Sato, Masayasu; Miura, Yukitoshi; JFT-2M Group

Nuclear Fusion, 43(10), p.1214 - 1219, 2003/10

no abstracts in English

Journal Articles

Observation of high recycling steady H-mode edge and compatibility with improved core confinement mode on JFT-2M

Kamiya, Kensaku; Kimura, Haruyuki; Ogawa, Hiroaki; Kawashima, Hisato; Tsuzuki, Kazuhiro; Sato, Masayasu; Miura, Yukitoshi; JFT-2M Group

Nuclear Fusion, 43(10), p.1214 - 1219, 2003/10

 Times Cited Count:34 Percentile:26.44(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:100(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Dynamics of plasma during the formation of a weak negative central magnetic shear configuration using counter neutral beam injection in the JFT-2M tokamak

Kamiya, Kensaku; Kimura, Haruyuki; Ogawa, Hiroaki; Kawashima, Hisato; Tsuzuki, Kazuhiro; Isei, Nobuaki; Sato, Masayasu; Shinohara, Koji

Purazuma, Kaku Yugo Gakkai-Shi, 78(12), p.1361 - 1367, 2002/12

no abstracts in English

JAEA Reports

Additional gleaning of fusion energy development

Yamamoto, Kenzo*; Koizumi, Koichi

JAERI-Review 2002-023, 156 Pages, 2002/09

JAERI-Review-2002-023.pdf:14.39MB

no abstracts in English

Journal Articles

Multichannel motional stark effect diagnostic discriminating radial electric field in the JFT-2M tokamak

Kamiya, Kensaku; Kimura, Haruyuki; Hoshino, Katsumichi; Isei, Nobuaki; Kawashima, Hisato; Ogawa, Hiroaki; Ogawa, Toshihide; Tsuzuki, Kazuhiro; Uehara, Kazuya; JFT-2M Group

Review of Scientific Instruments, 72(7), p.2931 - 2935, 2001/07

 Times Cited Count:6 Percentile:58.03(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

The Multichannel motional stark effect diagnostic system in the JFT-2M tokamak

Kamiya, Kensaku; Miura, Yukitoshi

JAERI-Tech 2000-090, 17 Pages, 2001/02

JAERI-Tech-2000-090.pdf:0.97MB

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:78.89(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Coherent magnetic fluctuations ergodized ELMy H-mode in the JFT-2M tokamak

W.Liu*; Miura, Yukitoshi; JFT-2M Group

Purazuma, Kaku Yugo Gakkai-Shi, 74(7), p.753 - 757, 1998/07

no abstracts in English

Journal Articles

Density fluctuations in the JFT-2M H-mode plasma measured by using a new analysis method of microwave reflectometry

Shinohara, Koji; Miura, Yukitoshi; Hoshino, Katsumichi

Purazuma, Kaku Yugo Gakkai-Shi, 74(6), p.607 - 615, 1998/06

no abstracts in English

Journal Articles

Rapid change of hydrogen neutral energy distribution at L/H-transition in JFT-2M H-mode

Miura, Yukitoshi; Okano, Fuminori; Suzuki, Norio; Mori, Masahiro; Hoshino, Katsumichi; Maeda, Hikosuke; Takizuka, Tomonori; JFT-2M Group; Ito, Sanae*; Ito, Kimitaka

NIFS-134, 20 Pages, 1992/02

no abstracts in English

JAEA Reports

Study on particle transport to wall in JFT-2M edge plasma by accelerator-based analysis

*; *; *; *; *; Sengoku, Seio; Otsuka, Hideo; Maeda, Hikosuke

JAERI-M 91-048, 57 Pages, 1991/03

JAERI-M-91-048.pdf:1.68MB

no abstracts in English

23 (Records 1-20 displayed on this page)