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Arai, Takashi; Nishiyama, Tomokazu; Yagyu, Junichi; Kasai, Satoshi; Sone, Isamu*; Abe, Mitsushi*; Miya, Naoyuki
Fusion Science and Technology, 45(1), p.65 - 68, 2004/01
Times Cited Count：2 Percentile：17.16(Nuclear Science & Technology)In a nuclear fusion experiment device, a plasma discharge is to be sustained for a long time in steady state operation. In such a device an electromagnetic sensor that has a signal integrator to measure direct currents will cause a technical problem of zero point drift on signals. So, the detection device using new technology for direct current measurement, optical current transformer (optical CT), was developed. The device has an optical fiber specified for 1550nm (wavelength) was manufactured, and was applied to JT-60U experiments. A gamma ray irradiation examination was also done to the optical CT
Kawai, Mikito; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kazawa, Minoru; Kikuchi, Katsumi*; Kuriyama, Masaaki; et al.
Fusion Science and Technology, 44(2), p.508 - 512, 2003/09
Times Cited Count：5 Percentile：36.77(Nuclear Science & Technology)The negative ion source for negative ion based neutral beam injector(N-NBI) of JT-60U aims at generating a negative ion beam with 500 keV and 22A for 10s. The N-NBI system was completed in 1996, followed by starting the efforts to increase beam power and energy. (1)Spatial non-uniformity of the source plasma causes position-dependent divergence of a beamlet due to mis-matching of local beam perveance. A part of the divergent energetic beams is intercepted by the grids and resultantly produce the excessive heat load of the grids and/or induce the high voltage breakdown. So several techniques to take measures against and to correct the non-uniformity in these sources were implemented. (2)Correction of beamlet deflection by adjusting the electric field at the extraction grids. It improved the beam divergence and then decreased an excessive heat load of a beam limiter by more than 50 %. As a result, the maximum injection power 6.2MW and beam pulse duration 10 seconds were obtaind.
Kaneko, Osamu*; Yamamoto, Takumi; Akiba, Masato; Hanada, Masaya; Ikeda, Katsunori*; Inoue, Takashi; Nagaoka, Kenichi*; Oka, Yoshihide*; Osakabe, Masaki*; Takeiri, Yasuhiko*; et al.
Fusion Science and Technology, 44(2), p.503 - 507, 2003/09
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)High energy negative-ion-based neutral beam injection (N-NBI) is expected as an efficient and reliable tool of heating and current driving for reactor plasmas such as ITER. A world wide activity on developing technology of negative ion production and beam formation started in 1980's and the great progress has been achieved up to now. In particular, Japan has two large projects that planned adopting N-NBI for real plasma experiments; the JT-60U tokamak and the LHD heliotron, which further motivated the R&D activity. These R&D programs were carried out at JAERI and NIFS separately in Japan, and both were successfully done. The first beam injection experiment was made on the JT-60U in 1996, followed by the LHD in 1998. They were the first experiments on heating plasma by high energy beam in tokamaks and in stellerators, and the obtained results were very promising.
Kudo, Yusuke; Sakurai, Shinji; Masaki, Kei; Urata, Kazuhiro*; Sasajima, Tadayuki; Matsukawa, Makoto; Sakasai, Akira; Ishida, Shinichi
Fusion Science and Technology, 44(2), p.333 - 337, 2003/09
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)A modification of the JT-60U is planned to a superconducting coil tokamak (JT-60SC) to establish steady-state operation of high beta plasma during a long duration of 100 s, and to ensure the plasma applicability of ferritic steel as reduced activation materials at reactor relevant break-even class plasma. This paper describes the detailed design of vacuum vessel, which has a unique structure for the cost effective manufacturing, and also the structural analysis results for the feasibility study. Eddy current and electromagnetic load analyses in case of stationary plasma disruption is performed and the result is used as the input for the static and dynamic analyses. As a result, the dynamic analysis is necessary to avoid unpredictable inertial force.
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pebble bed for a demo blanketHatano, Toshihisa; Enoeda, Mikio; Suzuki, Satoshi; Kosaku, Yasuo; Akiba, Masato
Fusion Science and Technology, 44(1), p.94 - 98, 2003/07
Times Cited Count：24 Percentile：81.79(Nuclear Science & Technology)no abstracts in English
Suzuki, Satoshi; Ueda, Yoshio*; Tokunaga, Kazutoshi*; Sato, Kazuyoshi; Akiba, Masato
Fusion Science and Technology, 44(1), p.41 - 48, 2003/07
Times Cited Count：28 Percentile：84.95(Nuclear Science & Technology)no abstracts in English
