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Shimada, Michiya; Miyazawa, Junichi*
Purazuma, Kaku Yugo Gakkai-Shi, 92(2), p.119 - 124, 2016/02
Actively convected liquid metal divertor is promising for providing a solution for issues of DEMO reactors including heat removal and disruptions. This chapter gives an overview of the motivation, research history, recent development, future perspective and issues to be resolved.
Kushida, Noriyuki
PLOS ONE (Internet), 10(3), p.e0122331_1 - e0122331_16, 2015/03
Times Cited Count：7 Percentile：45.28(Multidisciplinary Sciences)The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager's method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei's matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei's matrix, and matrices generated with the finite element method.
Seki, Masami; Moriyama, Shinichi; Shinozaki, Shinichi; Hasegawa, Koichi; Hiranai, Shinichi; Yokokura, Kenji; Shimono, Mitsugu; Terakado, Masayuki; Fujii, Tsuneyuki
Fusion Engineering and Design, 74(1-4), p.273 - 277, 2005/11
Times Cited Count：3 Percentile：24.22(Nuclear Science & Technology)no abstracts in English
Moriyama, Shinichi; Shinozaki, Shinichi
Japanese Journal of Applied Physics, Part 1, 44(8), p.6224 - 6229, 2005/08
Times Cited Count：1 Percentile：4.7(Physics, Applied)The control system of RF heating system in JT-60U has been improved with a concept of dispersion processing and featuring a real time waveform shaping method. It is proper that the brand-new, dispersion processing system has higher performance and reliability than old single processor system before modification, however it is worthy of mention that improvement on operation roll sharing, using the real time waveform shaping, has enabled more efficient and smooth operation. The typical roll sharing is that a simple rectangular waveform of the RF heating power is set by the experiment operator, and the waveform is re-shaped with the parameter set by the RF operator who knows deeply the condition of the RF system at that time. The simple and flexible composition of the new control system will also enable further improvement of hardware to enhance plasma performance that is inevitable to the devices for fusion experiment.
Takeuchi, Suehiro; Nakanoya, Takamitsu; Kabumoto, Hiroshi; Yoshida, Tadashi
Nuclear Instruments and Methods in Physics Research A, 513(3), p.429 - 438, 2003/11
Times Cited Count：3 Percentile：27.69(Instruments & Instrumentation)At the JAERI Tandem accelerator, an acceleration tube replacing plan is proceeding to increase the acceleration voltage toward 20 MV. Lengthy conditioning is generally necessary for a large tube system. We had an idea to clean the tubes with high-pressure water-jet rinsing before installation. We cleaned tubes and tested them at 1 MV and 3 MV. The both results exhibited that the voltages went beyond the rated voltages and discharge activities were much less than the old records. During the test of new tubes at 3 MV, the conditioning proceeded well and an extremely stable condition was fulfilled within 24 hours. In conclusion, the cleaning was found to be a very promising way to improve high-voltage performance of the tubes in a large tube system.
Masaki, Kei; Yagyu, Junichi; Arai, Takashi; Kaminaga, Atsushi; Kodama, Kozo; Miya, Naoyuki; Ando, Toshiro; Hiratsuka, Hajime; Saido, Masahiro
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.386 - 395, 2002/09
Times Cited Count：9 Percentile：51.46(Nuclear Science & Technology)The wall conditioning of JT-60U consists of the 300
C baking, He-TDC, He-GDC, tokamak discharge cleaning and boronization. Using these methods, total pressure of the vacuum vessel reached finally 10
10
Pa. The oxygen impurity was decreased to 0.5%. The experience with the carbon-based first wall showed that taper shaping is effective to reduce the local heat concentration to the tile edges. The observed poloidal asymmetric deposition of carbon on the divertor region implies that the carbon impurity produced in the outer divertor contributes to the deposition on the inner divertor. In 1992 and 1993, the B
C converted CFC tiles were installed in the outer divertor to reduce chemical sputtering of CFC tiles and oxygen impurity. The reduction was successfully demonstrated with the BC converted CFC tiles. In order to understand the tritium behavior in JT-60U, tritium in the first wall and the exhaust gas were measured. The estimated tritium inventory in the first wall was 50% of the generated tritium.
Higashijima, Satoru; JT-60 Team
Purazuma, Kaku Yugo Gakkai-Shi, 75(11), p.1297 - 1304, 1999/00
no abstracts in English
Yagyu, Junichi; Ogiwara, Norio; Saido, Masahiro; Okabe, Tomokazu; Hiratsuka, Hajime; Miyo, Yasuhiko; Naramoto, Hiroshi; Yamamoto, Shunya; Takeshita, Hidefumi; Aoki, Yasushi; et al.
Journal of Nuclear Materials, 241-243, p.579 - 584, 1997/00
Times Cited Count：15 Percentile：74.12(Materials Science, Multidisciplinary)no abstracts in English
Kimura, Toyoaki; JT-60 Team
16th IEEE/NPSS Symp. on Fusion Engineering (SOFE '95), 1, p.724 - 729, 1996/00
no abstracts in English
Maebara, Sunao; Seki, Masami; Suganuma, Kazuaki; Ikeda, Yoshitaka
Fusion Engineering and Design, 30, p.253 - 259, 1995/00
Times Cited Count：2 Percentile：28.12(Nuclear Science & Technology)no abstracts in English
Higashijima, Satoru*; Sugie, Tatsuo; Kubo, Hirotaka; Tsuji, Shunji; Shimada, Michiya; Asakura, Nobuyuki; Hosogane, Nobuyuki; Kawano, Yasunori; Nakamura, Hiroo; Itami, Kiyoshi; et al.
Journal of Nuclear Materials, 220-222, p.375 - 379, 1995/00
Times Cited Count：32 Percentile：92.83(Materials Science, Multidisciplinary)no abstracts in English
; JT-60 Team
15th IEEE/NPSS Symp. on Fusion Engineering,Vol. 2, 0, p.826 - 829, 1993/00
no abstracts in English
Ando, Toshiro; Takatsu, Hideyuki; Nakamura, Hiroo; Yamamoto, Masahiro; ; Arai, Takashi; Kaminaga, Atsushi; ; Horiike, Hiroshi; Shimizu, Masatsugu; et al.
Kaku Yugo Kenkyu, 65(SPECIAL ISSUE), p.27 - 49, 1991/03
no abstracts in English
; ; Murakami, Yoshio
Journal of Nuclear Materials, 91(1), p.223 - 226, 1980/00
Times Cited Count：8 Percentile：86.69(Materials Science, Multidisciplinary)no abstracts in English
Nihon Genshiryoku Gakkai-Shi, 20(2), p.87 - 89, 1978/02
no abstracts in English
*; ; ; ;
JAERI-M 6647, 16 Pages, 1976/07
no abstracts in English
