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Journal Articles

High power and high efficiency operation of 170GHz gyrotron

Kasugai, Atsushi; Minami, Ryutaro*; Takahashi, Koji; Kobayashi, Noriyuki; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Sakamoto, Keishi

Fusion Science and Technology, 51(2T), p.213 - 216, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

CO$$_{2}$$ laser collective Thomson scattering diagnostic of $$alpha$$-particles in burning plasmas

Kondoh, Takashi; Hayashi, Toshimitsu; Kawano, Yasunori; Kusama, Yoshinori; Sugie, Tatsuo; Hirata, Mafumi*; Miura, Yukitoshi

Fusion Science and Technology, 51(2T), p.62 - 64, 2007/02

 Times Cited Count:3 Percentile:26.87(Nuclear Science & Technology)

A diagnostic of fusion-generated $$alpha$$-particles is important for the understanding of their contribution to plasma heating and plasma instabilities in burning plasmas. However, an effective measurement method has not yet been established. In International Thermonuclear Experimental Reactor (ITER), measurement of velocity and spatial distributions of confined $$alpha$$-particles requires temporal resolution of 0.1 s and spatial resolution of a/10, where a is the plasma minor radius of ITER. A collective Thomson scattering (CTS) diagnostic for the measurement of $$alpha$$ particles is being developed using carbon dioxide (CO$$_{2}$$) lasers. The CTS based on the CO$$_{2}$$ laser (wavelength 10.6 $$mu$$m) has an advantage of small plasma refraction, simplifying the tracking of the scattered radiation. To realize the CTS diagnostic, a high-repetition Transversely Excited Atmospheric (TEA) CO$$_{2}$$ laser is being developed. The laser was designed based on a commercially available laser, TEA CO$$_{2}$$ marking laser. Maximum output energy of 36 J has been obtained with a cavity configuration of stable resonator. In order to obtain single-mode output, which is needed for CTS diagnostic, seed laser is injected to the cavity with unstable resonator. Using this technique, output energy of 10 J at a frequency of 10 Hz has been achieved with single-mode output. Proof-of-principle test will be performed with the improved laser system on the JT-60U tokamak. In this paper, we will describe development of the new TEA laser system, measurement results of the CTS on the JT-60U tokamak. Application of the CTS diagnostic to the mirror systems will be also described.

Journal Articles

Dynamics of SOL-divertor plasmas after an ELM crash in tokamak H-mode plasma

Takizuka, Tomonori; Hosokawa, Masanari*

Fusion Science and Technology, 51(2T), p.271 - 273, 2007/02

 Times Cited Count:2 Percentile:19.85(Nuclear Science & Technology)

Enhanced particle and heat fluxes to the divertor plates after an ELM crash in H-mode plasmas give the serious load to the plate. We investigate these fluxes with the particle simulation code PARASOL, where an electrostatic PIC method is combined with a Monte-Carlo binary collision model. The electron heat pulse after an ELM crash propagates fast to the plate. Next the ion heat pulse and plasma particle pulse reach the plate slowly with the sound-speed time scale. We study the effect of the ELM-induced-source asymmetry and of the recycling asymmetry on the dynamic behavior of SOL-divertor plasmas. The SOL current plays an important role in the dynamics with the asymmetry.

Journal Articles

Application of $$gamma$$ rays from D($$alpha$$,$$gamma$$)$$^{6}$$Li and $$^{19}$$F($$alpha$$,n)$$^{22}$$Na to alpha particle diagnostics

Ochiai, Kentaro; Kubota, Naoyoshi; Taniike, Akira*; Kitamura, Akira*; Kondo, Keitaro*; Nishitani, Takeo

Fusion Science and Technology, 51(2T), p.262 - 264, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

For the density of 3.5-MeV $$alpha$$ particle and the leakage $$alpha$$ particle in D-T plasmas, we propose the observation of 2.186-MeV $$gamma$$-ray produced by D($$alpha$$,$$gamma$$)$$^{6}$$Li reaction and the use of the activation method by $$^{19}$$F($$alpha$$,n)$$^{22}$$Na reaction, respectively. In order to verify these reaction rates, we have carried out the irradiation experiments by means of helium ion bombardment into a deuteride polyethylene and a calcium floride crystal samples. From our experiment, D($$alpha$$,$$gamma$$)$$^{6}$$Li reaction rate is estimated to be 10$$^{13}$$m$$^{-3}$$s$$^{-1}$$in the ITER typical plasma condition. So we obtained good prospect of the $$gamma$$-ray measurement as the confined $$alpha$$ diagnostics by using high efficiency detector. Also, it was found that The number of leakage alpha particles in order of 10$$^{18}$$m$$^{2}$$ could be estimated by the activation method with $$^{19}$$F($$alpha$$,n)$$^{22}$$Na.

Journal Articles

Fast measurement of ion temperature using filter charge exchange recombination spectroscopy system towards real-time plasma control in JT-60U

Yoshida, Maiko; Kobayashi, Shinji*; Takenaga, Hidenobu; Sakata, Shinya; Kamada, Yutaka; JT-60 Team

Fusion Science and Technology, 51(2T), p.301 - 303, 2007/02

 Times Cited Count:3 Percentile:26.87(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Two-dimensional spectroscopic measurement of hydrogen emission in JT-60U divertor plasmas

Fujimoto, Kayoko; Nakano, Tomohide; Kubo, Hirotaka; Kawashima, Hisato; Shimizu, Katsuhiro; Asakura, Nobuyuki

Fusion Science and Technology, 51(2T), p.247 - 249, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

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:19.85(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Progress in development of edge Thomson scattering system for ITER

Hatae, Takaki; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*; Ebisawa, Katsuyuki*; Kusama, Yoshinori; Sato, Kazuyoshi; Katsunuma, Atsushi*; Kubomura, Hiroyuki*; Shinobu, Katsuya*

Fusion Science and Technology, 51(2T), p.58 - 61, 2007/02

 Times Cited Count:6 Percentile:44.88(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:11.92(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

Atomic and molecular data base and data activities for fusion research in Japan Atomic Energy Agency

Sataka, Masao; Kubo, Hirotaka

Fusion Science and Technology, 51(2T), p.135 - 137, 2007/02

 Times Cited Count:2 Percentile:19.85(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Progress in microwave diagnostics and physics issues in magnetically confined plasmas

Mase, Atsushi*; Kogi, Yuichiro*; Hojo, Hitoshi*; Yoshikawa, Masayuki*; Itakura, Akiyoshi*; Chujo, T.*; Tokuzawa, Tokihiko*; Kawahata, Kazuo*; Nagayama, Yoshio*; Oyama, Naoyuki; et al.

Fusion Science and Technology, 51(2T), p.52 - 57, 2007/02

 Times Cited Count:3 Percentile:26.87(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Tokamak and spherical tokamak research in Japan

Takase, Yuichi*; Kikuchi, Mitsuru; Maekawa, Takashi*; Matsukawa, Makoto; Nagata, Masayoshi*; Nishio, Satoshi; Ono, Yasushi*; Sato, Konosuke*; Tobita, Kenji

Fusion Science and Technology, 51(2T), p.46 - 51, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Japanese tokamak and spherical tokamak (ST) research programs are described. Tokamak research will focus on steady state high($$beta$$$$_{N}$$ = 3.5-5.5) research on JT-60SA (formerly NCT) in support of ITER and DEMO. JT-60SA will also serve as the Satellite Tokamak under the JA-EU Broader Approach framework. ST research has been reorganized as the All-Japan ST Research Program, aiming for creative and innovative research focused on ultra-high and ultra-long pulse regimes. Results of plasma start-up, RF heating, and plasma merging reconnection experiments are summarized. Prospects of contribution of low aspect ratio tokamaks to fusion energy development, are presented.

Journal Articles

Upgrade program of ECRH system for GAMMA10

Imai, Tsuyoshi*; Tatematsu, Yoshinori*; Numakura, Tomoharu*; Sakamoto, Keishi; Minami, Ryutaro*; Watanabe, Osamu*; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Kamata, Yasuhiro*; Machida, Norihito*; et al.

Fusion Science and Technology, 51(2T), p.208 - 212, 2007/02

 Times Cited Count:9 Percentile:57.83(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Optimization of 28GHz gyrotron output performance for ECRH experiment of the GAMMA 10

Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Imai, Tsuyoshi*; Saito, Teruo*; Tatematsu, Yoshinori*; Sakamoto, Keishi; Minami, Ryutaro*; Watanabe, Osamu*; Numakura, Tomoharu*; Endo, Yoichi*

Fusion Science and Technology, 51(2T), p.397 - 399, 2007/02

 Times Cited Count:10 Percentile:60.87(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Characteristics of 28 GHz gyrotron for ECRH on GAMMA10

Kamata, Yasuhiro*; Imai, Tsuyoshi*; Tatematsu, Yoshinori*; Watanabe, Osamu*; Minami, Ryutaro*; Saito, Teruo*; Sakamoto, Keishi; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Machida, Norihito*; et al.

Fusion Science and Technology, 51(2T), p.412 - 414, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Advanced diagnostics for burning plasma experiments

Sasao, Mamiko*; Yamada, Hiroshi*; Baba, Mamoru*; Kondoh, Takashi; Peterson, B. J.*; Kawahata, Kazuo*; Mase, Atsushi*; Yoshikawa, Masayuki*; Azechi, Hiroshi*; Toi, Kazuo*; et al.

Fusion Science and Technology, 51(2T), p.40 - 45, 2007/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Several unexplored physics issues will be studied in burning plasma experiments, planned on ITER in the near future. To carry out these studies, it is essential to develop novel diagnostic systems, such as fusion product measurement systems and high-resolution, high-reliability profile measurement of various plasma parameters. Scientific research on "Advanced Diagnostics for Burning Plasma Experiment" was assigned as a priority area by MEXT in 2004, and more than 20 studies are currently underway under this program. The feasibility of several new diagnostic concepts applicable to ITER is examined and diagnostic components for these systems are now under development.

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