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Journal Articles

Neural-net predictor for beta limit disruptions in JT-60U

Yoshino, Ryuji

Nuclear Fusion, 45(11), p.1232 - 1246, 2005/11

 Times Cited Count:36 Percentile:74.89(Physics, Fluids & Plasmas)

Prediction of major disruptions observed at the $$beta$$-limit for tokamak plasmas has been investigated in JT-60U with developing neural networks. A sub-neural network is trained to output a value of the $$beta$$$$_{N}$$ limit every 2 ms. The target $$beta$$$$_{N}$$ limit is artificially set by the operator in the first step training and is modified in the second step training using the output $$beta$$$$_{N}$$ limit from the trained network. To improve the prediction performance further, the difference between the estimated $$beta$$$$_{N}$$ limit and the measured $$beta$$$$_{N}$$ and the other 11 parameters are inputted to a main neural network to calculate the stability level. Major disruptions have been predicted with a prediction success rate of 80% at 10 ms prior to the disruption while the false alarm rate is lower than 4%. This 80% is much higher than about 10% previously obtained. A prediction success rate of 90% has been also obtained with a false alarm rate of 12% at 10 ms prior to the disruption. This 12% is about a half of previously obtained one.

Journal Articles

Electron density behavior during fast termination phase of post-disruption runaway plasma

Kawano, Yasunori; Nakano, Tomohide; Asakura, Nobuyuki; Tamai, Hiroshi; Isayama, Akihiko; Kondoh, Takashi; Hatae, Takaki; Takenaga, Hidenobu; Ide, Shunsuke

Purazuma, Kaku Yugo Gakkai-Shi, 81(10), p.743 - 744, 2005/10

Electron density of post-disruption runaway plasmas in JT-60U has been measured by the tangential CO$$_{2}$$ laser interferometer. Increases in electron density after the first drop of runaway plasma current have been observed during a fast termination phase of the runaway plasma. At the second current drop, an increase in electron density with multiple spikes or oscillation with the period of 1 ms has been found. It is suggested that the increased electron density seems to take part in the shorter current decay time after the second current drop.

Journal Articles

Overview of goals and performance of ITER and strategy for plasma-wall interaction investigation

Shimada, Michiya; Costley, A. E.*; Federici, G.*; Ioki, Kimihiro*; Kukushkin, A. S.*; Mukhovatov, V.*; Polevoi, A. R.*; Sugihara, Masayoshi

Journal of Nuclear Materials, 337-339, p.808 - 815, 2005/03

 Times Cited Count:59 Percentile:96.3(Materials Science, Multidisciplinary)

ITER is an experimental fusion reactor for investigation and demonstration of burning plasmas, characterised of its heating dominated by alpha-particle heating. ITER is a major step from present devices and an indispensable step for fusion reactor development. ITER's success largely depends on the control of plasma-wall interactions(PWI), with power and particle fluxes and time scales one or two orders of magnitude larger than in present devices. The strategy for control of PWI includes the semi-closed divertor, strong fuelling and pumping, disruption and ELM control, replaceable plasma-facing materials and stepwise operation.

Journal Articles

Neural-net disruption predictor in JT-60U

Yoshino, Ryuji

Nuclear Fusion, 43(12), p.1771 - 1786, 2003/12

 Times Cited Count:42 Percentile:77.35(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Trial manufacture of rotary friction tester and frictional force measurement of metals

Abe, Tetsuya; Kanari, Moriyasu; Tanzawa, Sadamitsu; Hiroki, Seiji

JAERI-Tech 2002-093, 17 Pages, 2002/12

JAERI-Tech-2002-093.pdf:3.04MB

no abstracts in English

Journal Articles

Burn control in tokamak fusion reactors; Disruption and fast plasma shutdown

Yoshino, Ryuji

Purazuma, Kaku Yugo Gakkai-Shi, 75(12), p.1337 - 1374, 1999/12

no abstracts in English

Journal Articles

Fast plasma shutdown by killer pellet injection in JT-60U with reduced heat flux on the divertor plate and avoiding runaway electron generation

Yoshino, Ryuji; Kondoh, Takashi; Neyatani, Yuzuru; Itami, Kiyoshi; Kawano, Yasunori; Isei, Nobuaki

Plasma Physics and Controlled Fusion, 39(2), p.313 - 332, 1997/02

 Times Cited Count:97 Percentile:93.45(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Plasma equilibrium control during slow plasma current quench with avoidance of plasma-wall interaction in JT-60U

Yoshino, Ryuji; Nakamura, Yukiharu; Neyatani, Yuzuru

Nuclear Fusion, 37(8), p.1161 - 1166, 1997/00

 Times Cited Count:8 Percentile:31.68(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Electromagnetic analysis in the tokamak fusion reactor and large helical device

Koizumi, Koichi; Yamazaki, Kozo*

Purazuma, Kaku Yugo Gakkai-Shi, 72(12), p.1352 - 1361, 1996/12

no abstracts in English

JAEA Reports

Assessment on F/W electrical cutting for reduction of electromagnetic force on the blanket module

*; Komatsuzaki, Manabu*; Nishio, Satoshi; Koizumi, Koichi; Takatsu, Hideyuki

JAERI-Tech 96-031, 16 Pages, 1996/07

JAERI-Tech-96-031.pdf:0.94MB

no abstracts in English

Journal Articles

High-speed surface temperature measurements on plasma facing materials for fusion applications

Araki, Masanori; *

Review of Scientific Instruments, 67(1), p.178 - 184, 1996/01

 Times Cited Count:4 Percentile:43.83(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Avoidance of VDEs during plasma current quench in JT-60U

Yoshino, Ryuji; Nakamura, Yukiharu; Neyatani, Yuzuru

Nuclear Fusion, 36(3), p.295 - 307, 1996/00

 Times Cited Count:33 Percentile:72.07(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Recent R&D activities on plasma facing components at JAERI

Sato, Kazuyoshi; ; Araki, Masanori; Nakamura, Kazuyuki; Watanabe, Kazuhiro; ; Dairaku, Masayuki; Okumura, Yoshikazu; Ohara, Yoshihiro; Akiba, Masato

16th IEEE/NPSS Symp. on Fusion Engineering (SOFE '95), 1, p.220 - 223, 1995/00

no abstracts in English

Journal Articles

Disruption amelioration experiments in JT-60U and JET

Yoshino, Ryuji; Neyatani, Yuzuru; Isei, Nobuaki; Koide, Yoshihiko; Kawano, Yasunori; A.Tanga*; Campbell, D. J.*; M.F.Johnson*; L.Rossi*

IAEA-CN-60/A5-8, 0, p.685 - 695, 1995/00

no abstracts in English

Journal Articles

Applicability of eddy current analysis by a network mesh method to electromagnetomechanical problems and its experimental verification

Nishio, Satoshi; Miura, H.*; *

International Journal of Applied Electromagnetics and Mechanics, 6, p.37 - 54, 1995/00

no abstracts in English

Journal Articles

Effects of plasma disruption on structural and plasma-facing materials

Akiba, Masato; Madarame, Haruki*

Journal of Nuclear Materials, 212-215(1), p.90 - 96, 1994/09

no abstracts in English

JAEA Reports

Development of integrated insulation joint for cooling pipe in tokamak reactor

Nishio, Satoshi; Abe, Tetsuya; *; Yamazaki, Seiichiro*

JAERI-Tech 94-006, 18 Pages, 1994/08

JAERI-Tech-94-006.pdf:0.82MB

no abstracts in English

JAEA Reports

Design & fabrication of disruption simulation coil

Iwamoto, Shuichi*; Ando, Toshinari

JAERI-M 93-071, 18 Pages, 1993/03

JAERI-M-93-071.pdf:0.63MB

no abstracts in English

Journal Articles

Softening of Current quenches in JT-60U

Yoshino, Ryuji; Neyatani, Yuzuru; Hosogane, Nobuyuki; S.W.Wolfe*; Matsukawa, Makoto; Ninomiya, Hiromasa

Nuclear Fusion, 33(11), p.1599 - 1612, 1993/00

 Times Cited Count:33 Percentile:71.78(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Experimental and analytical studies on thermal erosion of carbon-based materials with high thermal conductivity

Akiba, Masato; Araki, Masanori; ; Ise, Hideo*; Nakamura, Kazuyuki; ; Dairaku, Masayuki; Tanaka, Shigeru

Journal of Nuclear Materials, 191-194, p.373 - 376, 1992/00

no abstracts in English

31 (Records 1-20 displayed on this page)