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411 results on '"S. Hamaguchi"'

1. Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions

Author

K. Ida, M. Yoshinuma, M. Kobayashi, T. Kobayashi, N. Kenmochi, F. Nespoli, R.M. Magee, F. Warmer, A. Dinklage, A. Matsuyama, R. Sakamoto, T. Nasu, T. Tokuzawa, T. Kinoshita, K. Tanaka, N. Tamura, K. Nagaoka, M. Nishiura, Y. Takemura, K. Ogawa, G. Motojima, T. Oishi, Y. Morishita, J. Varela, W.H.J. Hayashi, M. Markl, H. Bouvain, Y. Liang, M. Leconte, D. Moseev, V.E. Moiseenko, C.G. Albert, I. Allfrey, A. Alonso, F.J. Arellano, N. Ashikawa, A. Azegami, L. Bardoczi, M. van Berkel, M. Beurskens, M.W. Binderbaue, A. Bortolon, S. Brezinsek, R. Bussiahn, A. Cappa, D. Carralero, I.C. Chan, J. Cheng, X. Dai, D.J. Den Hartog, C.P. Dhard, F. Ding, A. Ejiri, S. Ertmer, T. Fornal, K. Fujita, Y. Fujiwara, H. Funaba, L. Garcia, J.M. Garcia-Regana, I. Garcia-Cortés, I.E. Garkusha, D.A. Gates, Y. Ghai, E.P. Gilson, H. Gota, M. Goto, E.M. Green, V. Haak, S. Hamaguchi, K. Hanada, H. Hara, D. Hartmann, Y. Hayashi, T. Henning, C. Hidalgo, J. Hillairet, R. Hutton, T. Ido, H. Igami, K. Ikeda, S. Inagaki, A. Ishizawa, S. Ito, M. Isobe, Y. Isobe, M. Ivkovic, Z. Jiang, J. Jo, S. Kamio, H. Kasahara, D. Kato, Y. Katoh, Y. Kawachi, Y. Kawamoto, G. Kawamura, T. Kawate, Ye.O. Kazakov, V. Klumper, A. Knieps, W.H. Ko, S. Kobayashi, F. Koike, Yu.V. Kovtun, M. Kubkowska, S. Kubo, S.S.H. Lam, A. Langenberg, H. Laqua, S. Lazerson, J. Lestz, B. Li, L. Liao, Z. Lin, R. Lunsford, S. Masuzaki, H. Matsuura, K.J. McCarthy, D. Medina-Roque, O. Mitarai, A. Mollen, C. Moon, Y. Mori, T. Morisaki, S. Morita, K. Mukai, I. Murakami, S. Murakami, T. Murase, C.M. Muscatello, K. Nagasaki, D. Naujoks, H. Nakano, M. Nakata, Y. Narushima, A. Nagy, J.H. Nicolau, T. Nishizawa, S. Nishimoto, H. Nuga, M. Nunami, R. Ochoukov, S. Ohdachi, J. Ongena, M. Osakabe, N.A. Pablant, N. Panadero, B. Peterson, J. de la Riva Villén, J. Romazanov, J. Rosato, M. Rud, S. Sakakibara, H.A. Sakaue, H. Sakai, I. Sakon, M. Salewski, S. Sangaroon, S. Sereda, T. Stange, K. Saito, S. Satake, R. Seki, T. Seki, S. Sharapov, A. Shimizu, T. Shimozuma, G. Shivam, M. Shoji, D.A. Spong, H. Sugama, Z. Sun, C. Suzuki, Y. Suzuki, T. Tajima, E. Takada, H. Takahashi, K. Toi, Y. Tsuchibushi, N. Tsujii, K. Tsumori, T.I. Tsujimurai, G. Ueno, H. Uehara, J.L. Velasco, E. Wang, K.Y. Watanabe, T. Wauter, U. Wenzel, M. Yajima, H. Yamada, I. Yamada, K. Yanagihara, H. Yamaguchi, R. Yanai, R. Yasuhara, M. Yokoyama, Y. Yoshimura, M. Zarnstorff, M. Zhao, G.Q. Zhong, Q. Zhou, S. Ziaei, LHD Experiment Group, and the W7-X Team

Subjects
Large Helical Device, basic plasma physics, burning plasma, wave–particle interaction, ion mixing, turbulence spreading, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues in burning plasma are: alpha-channeling (ion heating by alpha particles), turbulence and transport in electron dominant heating helium ash exhaust, reduction of the divertor heat load. To solve these problems, understanding the basic plasma physics of (1) wave–particle interaction through (inverse) Landau damping, (2) characteristics of electron-scale (high- k ) turbulence, (3) ion mixing and the isotope effect, and (4) turbulence spreading and detachment, is necessary. This overview discusses the experimental studies on these issues and turbulent transport in multi-ion plasma and other issues in the appendix.

Published
2024
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2. The 2022 Plasma Roadmap: low temperature plasma science and technology

Author

I Adamovich, S Agarwal, E Ahedo, L L Alves, S Baalrud, N Babaeva, A Bogaerts, A Bourdon, P J Bruggeman, C Canal, E H Choi, S Coulombe, Z Donkó, D B Graves, S Hamaguchi, D Hegemann, M Hori, H-H Kim, G M W Kroesen, M J Kushner, A Laricchiuta, X Li, T E Magin, S Mededovic Thagard, V Miller, A B Murphy, G S Oehrlein, N Puac, R M Sankaran, S Samukawa, M Shiratani, M Šimek, N Tarasenko, K Terashima, E Thomas Jr, J Trieschmann, S Tsikata, M M Turner, I J van der Walt, M C M van de Sanden, and T von Woedtke

Published
2022
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3. The tension at the top of the animal pole decreases during meiotic cell division.

Author

Setsuko K Satoh, Akifumi Tsuchi, Ryohei Satoh, Hiromi Miyoshi, Miyako S Hamaguchi, and Yukihisa Hamaguchi

Subjects
Medicine, Science
Abstract

Meiotic maturation is essential for the reproduction procedure of many animals. During this process an oocyte produces a large egg cell and tiny polar bodies by highly asymmetric division. In this study, to fully understand the sophisticated spatiotemporal regulation of accurate oocyte meiotic division, we focused on the global and local changes in the tension at the surface of the starfish (Asterina pectinifera) oocyte in relation to the surface actin remodeling. Before the onset of the bulge formation, the tension at the animal pole globally decreased, and started to increase after the onset of the bulge formation. Locally, at the onset of the bulge formation, tension at the top of the animal pole began to decrease, whereas that at the base of the bulge remarkably increased. As the bulge grew, the tension at the base of the bulge additionally increased. Such a change in the tension at the surface was similar to the changing pattern of actin distribution. Therefore, meiotic cell division was initiated by the bulging of the cortex, which had been weakened by actin reduction, and was followed by contraction at the base of the bulge, which had been reinforced by actin accumulation. The force generation system is assumed to allow the meiotic apparatus to move just under the membrane in the small polar body. Furthermore, a detailed comparison of the tension at the surface and the cortical actin distribution indicated another sophisticated feature, namely that the contraction at the base of the bulge was more vigorous than was presumed based on the actin distribution. These features of the force generation system will ensure the precise chromosome segregation necessary to produce a normal ovum with high accuracy in the meiotic maturation.

Published
2013
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4. The Tension at the Top of the Animal Pole Decreases during Meiotic Cell Division

Author

Hiromi Miyoshi, Akifumi Tsuchi, Miyako S. Hamaguchi, Yukihisa Hamaguchi, Ryohei Satoh, and Setsuko K. Satoh

Subjects
Multidisciplinary, Polarity in embryogenesis, lcsh:R, Actin remodeling, lcsh:Medicine, Anatomy, Biology, Models, Theoretical, Oocyte, Cell biology, Chromosome segregation, Polar body, Starfish, medicine.anatomical_structure, Spatio-Temporal Analysis, Meiosis, Bulge, medicine, Oocytes, Animals, lcsh:Q, lcsh:Science, Actin, Cell Division, Research Article
Abstract

Meiotic maturation is essential for the reproduction procedure of many animals. During this process an oocyte produces a large egg cell and tiny polar bodies by highly asymmetric division. In this study, to fully understand the sophisticated spatiotemporal regulation of accurate oocyte meiotic division, we focused on the global and local changes in the tension at the surface of the starfish (Asterina pectinifera) oocyte in relation to the surface actin remodeling. Before the onset of the bulge formation, the tension at the animal pole globally decreased, and started to increase after the onset of the bulge formation. Locally, at the onset of the bulge formation, tension at the top of the animal pole began to decrease, whereas that at the base of the bulge remarkably increased. As the bulge grew, the tension at the base of the bulge additionally increased. Such a change in the tension at the surface was similar to the changing pattern of actin distribution. Therefore, meiotic cell division was initiated by the bulging of the cortex, which had been weakened by actin reduction, and was followed by contraction at the base of the bulge, which had been reinforced by actin accumulation. The force generation system is assumed to allow the meiotic apparatus to move just under the membrane in the small polar body. Furthermore, a detailed comparison of the tension at the surface and the cortical actin distribution indicated another sophisticated feature, namely that the contraction at the base of the bulge was more vigorous than was presumed based on the actin distribution. These features of the force generation system will ensure the precise chromosome segregation necessary to produce a normal ovum with high accuracy in the meiotic maturation.

Published
2013

5. Liner conformality in ionized magnetron sputter metal deposition processes

Author

S. M. Rossnagel and S. Hamaguchi

Subjects
Materials science, business.industry, Metallurgy, General Engineering, Tantalum, chemistry.chemical_element, Tungsten, Sputter deposition, chemistry, Sputtering, Trench, Cavity magnetron, Optoelectronics, Deposition (phase transition), Thin film, business
Abstract

S. Hamaguchi and S. M. Rossnagel, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 14, 2603 (1996) https://doi.org/10.1116/1.588993, The conformality of thin metal films (liners) formed on high-aspect-ratio trench structures in ionized magnetron sputter deposition processes is studied numerically and experimentally. The numerical simulator (SHADE) used to predict the surface topography is based on the shock-tracking method for surface evolution. The simulation results are in good agreement with experimentally observed thin-film topography. It is shown that combination of direct deposition and trench-bottom resputtering results in good conformality of step coverages and the amount of the resputtering needed for the good conformality is almost independent of trench aspect ratios. © 1996 American Vacuum Society.

Published
1996

6. Performance of upgraded cooling system for LHD helical coils

Author

S. Hamaguchi, S. Imagawa, T. Obana, N. Yanagi, S. Moriuchi, H. Sekiguchi, K. Oba, T. Mito, O. Motojima, T. Okamura, T. Semba, S. Yoshinaga, H. Wakisaka, J. G. Weisend, John Barclay, Susan Breon, Jonathan Demko, Michael DiPirro, J. Patrick Kelley, Peter Kittel, Arkadiy Klebaner, Al Zeller, Mark Zagarola, Steven Van Sciver, Andrew Rowe, John Pfotenhauer, Tom Peterson, and Jennifer Lock

Subjects
Quantitative Biology::Biomolecules, business.industry, Nuclear engineering, Physics::Medical Physics, Electrical engineering, chemistry.chemical_element, Cryogenics, Superconducting magnet, Physics::Fluid Dynamics, Subcooling, Large Helical Device, chemistry, Heat exchanger, Physics::Atomic and Molecular Clusters, Water cooling, Physics::Atomic Physics, Lambda point refrigerator, business, Helium
Abstract

Helical coils of the Large Helical Device (LHD) are large scale superconducting magnets for heliotron plasma experiments. The helical coils had been cooled by saturated helium at 4.4 K, 120 kPa until 2005. An upgrade of the cooling system was carried out in 2006 in order to improve the cryogenic stability of the helical coils and then it has been possible to supply the coils with subcooled helium at 3.2 K, 120 kPa. A designed mass flow of the supplied subcooled helium is 50 g/s. The subcooled helium is generated at a heat exchanger in a saturated helium bath. A series of two centrifugal cold compressors with gas foil bearing is utilized to lower the helium pressure in the bath. The supplied helium temperature is regulated by rotational speed of the cold compressors and power of a heater in the bath. The mass flow of the supplied helium is also controlled manually by a supply valve and its surplus is evaporated by ten heaters at the outlet above the coils. In the present study, the performance of the cooli...

Published
2007

7. Wave-particle power transfer in a steady-state driven system

Author

H. L. Berk, B. N. Breizman, and S. Hamaguchi

Subjects
Fluid Flow and Transfer Processes, Physics, Steady state, Ion beam, Waves in plasmas, Computational Mechanics, General Physics and Astronomy, Plasma, Mechanics, Condensed Matter Physics, Amplitude, Distribution function, Physics::Plasma Physics, Mechanics of Materials, Phase space, Maximum power transfer theorem, Atomic physics
Abstract

H. L. Berk, Physics of Fluids B: Plasma Physics 2, 3212 (1990) https://doi.org/10.1063/1.859232, The general expression of the power transfer from a high-energy ion beam to a background electrostatic plasma wave is obtained for arbitrary wave amplitude. It is verified that phase space gradients produced by a finite amplitude wave enhance the power transfer significantly. © 1990 American Institute of Physics.

Published
1990

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