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Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:17 Percentile:8.28(Materials Science, Multidisciplinary)

Journal Articles

Development of divertor simulation research in the GAMMA 10/PDX tandem mirror

Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

Journal Articles

X-ray backscattering study of crystal lattice distortion in hidden order of URu$$_2$$Si$$_2$$

Tabata, Chihiro*; Inami, Toshiya; Michimura, Shinji*; Yokoyama, Makoto*; Hidaka, Hiroyuki*; Yanagisawa, Tatsuya*; Amitsuka, Hiroshi*

Philosophical Magazine, 94(32-33), p.3691 - 3701, 2014/00

 Times Cited Count:12 Percentile:35.64(Materials Science, Multidisciplinary)

Journal Articles

Observation of ion cyclotron emission owing to DD fusion product H ions in JT-60U

Sato, Shoichi*; Ichimura, Makoto*; Yamaguchi, Yusuke*; Katano, Makoto*; Imai, Yasutaka*; Murakami, Tatsuya*; Miyake, Yuichiro*; Yokoyama, Takuro*; Moriyama, Shinichi; Kobayashi, Takayuki; et al.

Plasma and Fusion Research (Internet), 5, p.S2067_1 - S2067_4, 2010/12

Ion cyclotron emissions (ICEs) due to deuterium-deuterium fusion-product (FP) ions on JT-60U are studied. ICE due to H-ions is identified from the difference of the toroidal wave number of 2nd ICE(D). The parameter dependence for the appearance of ICE(H) is investigated from the experimental conditions and also is studied by using "Escape Particle Orbit analysis Code (EPOC)".

Journal Articles

Observation of spontaneously excited waves in the ion cyclotron frequency range on JT-60U

Ichimura, Makoto*; Higaki, Hiroyuki*; Kakimoto, Shingo*; Yamaguchi, Yusuke*; Nemoto, Tatsuki*; Katano, Makoto*; Ishikawa, Masao; Moriyama, Shinichi; Suzuki, Takahiro

Nuclear Fusion, 48(3), p.035012_1 - 035012_7, 2008/03

 Times Cited Count:27 Percentile:24.41(Physics, Fluids & Plasmas)

In this paper, experimental observations of spontaneously excited waves in the ion cyclotron range of frequency (ICRF) on JT-60U are described. The fluctuations in ICRF are driven by the presence of non-thermal ion distribution in magnetic confinement plasmas. Two types of magnetic fluctuations are detected: one is due to high energy D ions from neutral beam injections and the other is due to fusion products (FPs) of $$^{3}$$He and T ions. These fluctuations have been reported as ion cyclotron emissions (ICEs) in the burning plasma experiments on large tokamaks. This paper describes the first measurement of the spatial structures of the excited modes in the poloidal and toroidal directions. It is confirmed by using ICRF antennas as magnetic probes that all modes excited spontaneously have magnetic components and couple to the antenna straps. The modes due to D ions have small toroidal wave number $$kappa$$$$_{z}$$ and will behave as electrostatic waves. On the while, the measurement of finite $$kappa$$$$_{z}$$ in the modes due to FP ions supports the excitation of the Alfv$'e$n waves is the possible origin of FP-ICEs. It is also confirmed that the excited modes due to FP ions have different wave structures and are suggested to be in the different branch of the Alfv$'e$n waves, that is, the fast Alfv$'e$n wave and the slow Alfv$'e$n wave. Frequency peaks due to FP ions are sometimes split into doublet shape as observed in JET experiments. The phase differences of both peaks are measured and indicate that two waves are traveling in both toroidal directions. Both beam-driven ICEs and FP-ICEs are observed and those spatial structures are obtained on JT-60U.

Journal Articles

Observation of radial particle transport induced by the fluctuation measured with a gold neutral beam probe

Kojima, Atsushi; Ishii, Kameo*; Miyata, Yoshiaki*; Kakiuchi, Hideto*; Kaido, Norihiro*; Yoshikawa, Masayuki*; Itakura, Akiyoshi*; Ichimura, Makoto*; Chujo, T.*

Fusion Science and Technology, 51(2T), p.274 - 276, 2007/02

 Times Cited Count:2 Percentile:79.49(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Wave excitation in magnetically confined plasmas with an anisotropic velocity distribution

Ichimura, Makoto*; Higaki, Hiroyuki*; Kakimoto, Shingo*; Yamaguchi, Yusuke*; Nemoto, Kenju*; Katano, Makoto*; Kozawa, Isao*; Muro, Taishi*; Ishikawa, Masao; Moriyama, Shinichi; et al.

Fusion Science and Technology, 51(2T), p.150 - 153, 2007/02

 Times Cited Count:1 Percentile:87.73(Nuclear Science & Technology)

In magnetically confined plasmas, fluctuations in the ion cyclotron range of frequency (ICRF) will be driven by the presence of non-thermal ion energy distribution. In strong ICRF heating experiments on the GAMMA 10 tandem mirror, plasmas with a strong temperature anisotropy have been formed. Alfven-ion-cyclotron (AIC) modes are spontaneously excited due to strong temperature anisotropy. High-energy ions are trapped in the local mirror and will form the velocity distribution with the strong anisotropy. To study the relation among the AIC modes, ICEs and beam-driven electrostatic instabilities with non-thermal energy distribution is the main purpose of this work. When the NBs are injected, the magnetic fluctuations due to injected beams and FP ions are detected by ICRF antennas used as pickup loops on JT-60U. The wave excitation near ion cyclotron and its higer harmonic frequencies are studied experimentally and theoretically in plasmas with non-thermal ion energy distribution.

Journal Articles

Overview of national centralized tokamak program; Mission, design and strategy to contribute ITER and DEMO

Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.

Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12

To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.

Journal Articles

Overview of the national centralized tokamak programme

Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.

Nuclear Fusion, 46(3), p.S29 - S38, 2006/03

 Times Cited Count:13 Percentile:54.2(Physics, Fluids & Plasmas)

The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.

Journal Articles

Engineering design and control scenario for steady-state high-beta operation in national centralized tokamak

Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.

Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02

 Times Cited Count:1 Percentile:89.15(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Design study of national centralized tokamak facility for the demonstration of steady state high-$$beta$$ plasma operation

Tamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.

Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12

 Times Cited Count:15 Percentile:50.65(Physics, Fluids & Plasmas)

Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.

Journal Articles

Progress in physics and technology developments for the modification of JT-60

Tamai, Hiroshi; Matsukawa, Makoto; Kurita, Genichi; Hayashi, Nobuhiko; Urata, Kazuhiro*; Miura, Yushi; Kizu, Kaname; Tsuchiya, Katsuhiko; Morioka, Atsuhiko; Kudo, Yusuke; et al.

Plasma Science and Technology, 6(1), p.2141 - 2150, 2004/02

 Times Cited Count:2 Percentile:92.83(Physics, Fluids & Plasmas)

The dominant issue for the the modification program of JT-60 (JT-60SC) is to demonstrate the steady state reactor relevant plasma operation. Physics design on plasma parameters, operation scenarios, and the plasma control method are investigated for the achievement of high-$$beta$$. Engineering design and the R&D on the superconducting magnet coils, radiation shield, and vacuum vessel are performed. Recent progress in such physics and technology developments is presented.

Journal Articles

Objectives and design of the JT-60 superconducting tokamak

Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Chujo, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.

Nuclear Fusion, 43(7), p.606 - 613, 2003/07

no abstracts in English

Journal Articles

Objectives and design of the JT-60 superconducting tokamak

Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Cho, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.

Nuclear Fusion, 43(7), p.606 - 613, 2003/07

 Times Cited Count:33 Percentile:27.31(Physics, Fluids & Plasmas)

no abstracts in English

Oral presentation

ICRF waves for plasma diagnostics in GAMMA 10 and JT-60U

Ichimura, Makoto*; Yamaguchi, Yusuke*; Nemoto, Kenju*; Katano, Makoto*; GAMMA10 Group*; Ishikawa, Masao*; Moriyama, Shinichi; Suzuki, Takahiro

no journal, , 

The measurement of fusion product (FP) ICEs will become a significant diagnostic tool for fusion reactions. The precise study of the excitation mechanism is important for future burning plasma experiments. In strong ICRF heating experiments on the GAMMA 10 tandem mirror, plasmas with a strong temperature anisotropy have been formed when the resonance layer exists near the mid-plane of the central cell. In a typical discharge, Alfven-ion-cyclotron (AIC) modes are spontaneously excited due to such a strong temperature anisotropy. On the while, the injection of low power ICRF waves into the plasma as active diagnostics has been tested in GAMMA 10. A wide band ICRF probe system was constructed. In the present experimental conditions, the inhomogeneity scale length of the plasma and the magnetic field configuration is in the same order of the wavelength. Wave excitation is strongly affected by the boundary conditions. The waves excited in the plasma are detected with a magnetic probe. In the presentation, the experimental results of the ICRF probe system in GAMMA 10 for active diagnostics and the observation of ICEs in JT-60U for passive diagnostics are reported.

Oral presentation

Plasma diagnostics with ICRF waves in GAMMA 10 and JT-60U

Ichimura, Makoto*; Higaki, Hiroyuki*; Yamaguchi, Yusuke*; Nemoto, Tatsuki*; Katano, Makoto*; Motegi, Yukimi*; Kozawa, Isao*; Muro, Taishi*; Ishikawa, Masao; Moriyama, Shinichi; et al.

no journal, , 

The wave excitation in the ion cyclotron range of frequency (ICRF) is strongly affected by the boundary conditions. The formation of eigenmodes depends on the plasma parameters, their spatial profiles, the magnetic field profile and so on. The main subject of this presentation is the establishment of plasma diagnostics with ICRF waves. In GAMMA 10, the injection of low power ICRF waves into the plasma as active diagnostics has been tested. The preliminary results are reported. In JT-60U, the ion cyclotron emissions (ICEs) due to high energy ions from the neutral beam injections and the fusion reactions have been clearly observed. The frequency spectra of ICEs also depend on the plasma parameters. ICEs for passive diagnostic tools are discussed.

Oral presentation

Study of spontaneously excited waves on plasmas with anisotropic velocity distribution

Katano, Makoto*; Ichimura, Makoto*; Yamaguchi, Yusuke*; Motegi, Yukimi*; Muro, Taishi*; Ouchi, Toshiaki*; Oishi, Junya*; Sato, Shoichi*; Ishikawa, Masao; Moriyama, Shinichi; et al.

no journal, , 

The understanding of spontaneously excited waves in plasmas with anisotropic velocity distributions is the main purpose of this presentation. In JT-60U, the ion cyclotron emissions (ICEs) due to fusion product ions have been experimentally observed. By using the local dispersion relation in hot plasmas, the excitation of slow and fast Alfv$'e$n waves are evaluated. The excitation mechanism for ICEs due to fusion product ions are discussed.

Oral presentation

Spontaneous excitation of waves due to anisotropic velocity distribution in GAMMA 10 and JT-60U

Ichimura, Makoto*; Yamaguchi, Yusuke*; Sato, Shoichi*; Katano, Makoto*; Ouchi, Toshiaki*; Muro, Taishi*; Sekihara, Yusuke*; Murakami, Tatsuya*; Moriyama, Shinichi; Kobayashi, Takayuki; et al.

no journal, , 

Fluctuations in the ion cyclotron range of frequency are investigated both on GAMMA 10 and JT-60U. Ion cyclotron emissions (ICEs) due to deuterium-deuterium fusion-product (FP) ions on JT-60U are described. ICE due to H-ions is newly identified. ICE(T) with lower frequency has larger wave numbers than ICE ($$^{3}$$He) in the same discharge. The excitation of slow Alfv$'e$n waves is elucidated for the first time as the mechanism for ICE due to T-ions. The anisotropy of T-ions at the outer plasma edge is evaluated by using Escape Particle Orbit analysis Code (EPOC).

Oral presentation

Study of the ion cyclotron emission due to D-D fusion-product H-ions on JT-60U

Sato, Shoichi*; Ichimura, Makoto*; Yamaguchi, Yusuke*; Katano, Makoto*; Imai, Yasutaka*; Murakami, Tatsuya*; Miyake, Yuichiro*; Yokoyama, Takuro*; Moriyama, Shinichi; Kobayashi, Takayuki; et al.

no journal, , 

Ion cyclotron emissions (ICEs) due to deuterium-deuterium fusion-product (FP) ions on JT-60U are studied. ICE due to H-ions is identified from the difference of the toroidal wave number of 2nd ICE(D). The parameter dependence for the appearance of ICE(H) is investigated from the experimental conditions and also is studied by using "Escape Particle Orbit analysis Code (EPOC)".

Oral presentation

Spontaneously excited waves in the ion cyclotron range of frequency on fusion devices

Ichimura, Makoto*; Yamaguchi, Yusuke*; Sato, Shoichi*; Moriyama, Shinichi; Kobayashi, Takayuki; Kojima, Atsushi

no journal, , 

In fusion-oriented devices, Alfven waves are spontaneously excited due to the existence of non-thermal energy component and anisotropy in the ion energy distribution. In the ion cyclotron range of frequency (ICRF), Alfven ion cyclotron (AIC) modes are spontaneously excited due to the strong temperature anisotropy and fast Alfven waves are observed as the ion cyclotron emission (ICE) in the burning plasma experiments. Experimental observations in GAMMA 10 and JT-60U are reviewed.

25 (Records 1-20 displayed on this page)