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Your search keyword '"Nagashima, Y."' showing total 13 results
Start Over Author "Nagashima, Y." Journal aip conference proceedings
13 results on '"Nagashima, Y."'

1. Ion-induced Processes in Polymer Composite Materials: Positron Annihilation Spectroscopy in Combination with UV-Vis Absorption and Raman Spectroscopy.

Author

Kavetskyy, T., Kuczumow, A., Iida, K., Nagashima, Y., Liedke, M. O., Butterling, M., Wagner, A., Krause-Rehberg, R., Šauša, O., Petkova, T., Boev, V., Kiv, A., and Stepanov, A. L.

Subjects
RAMAN spectroscopy, COMPOSITE materials, ULTRAVIOLET-visible spectroscopy, POSITRON annihilation, POSITRON beams, COMPOSITE numbers
Abstract

Application of positron annihilation spectroscopy using a variable-energy slow positron beam (VESPB) as a key experimental tool to understand ion-induced processes and defect structures in a number of polymer composite materials important for a practical use is demonstrated. The results concerning 40 keV B+ implanted polymethylmethacrylate (B:PMMA) and 30 keV Ag+ implanted PMMA (Ag:PMMA), and organic-inorganic ureasil composite (Ag:ureasil) are discussed. Utilized VESPB techniques allow to confirm carbonization of ion-irradiated B:PMMA, formation of carbon-shell Ag-core nanoparticles in Ag:PMMA and evolution in size of Ag nanoparticles in Ag:ureasil, which was revealed by means of UV-Vis absorption and Raman spectroscopy measurements. [ABSTRACT FROM AUTHOR]

Published
2019
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2. Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2

Author

Wakatsuki, T., primary, Ejiri, A., additional, Shinya, T., additional, Takase, Y., additional, Furui, H., additional, Hiratsuka, J., additional, Imamura, K., additional, Inada, T., additional, Kakuda, H., additional, Kasahara, H., additional, Nagashima, Y., additional, Nakamura, K., additional, Nakanishi, A., additional, Oosako, T., additional, Saito, K., additional, Seki, T., additional, Shimpo, F., additional, Sonehara, M., additional, Togashi, H., additional, Tsuda, S., additional, Tsujii, N., additional, and Yamaguchi, T., additional

Published
2014
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3. Towards the production of anti-hydrogen beams

Author

Higaki, H., primary, Enomoto, Y., additional, Kuroda, N., additional, Michishio, K., additional, Murtagh, D. J., additional, Ulmer, S., additional, Van Gorp, S., additional, Kim, C. H., additional, Nagata, Y., additional, Kanai, Y., additional, Torii, H. A., additional, Corradini, M., additional, Leali, M., additional, Lodi-Rizzini, E., additional, Mascagna, V., additional, Venturelli, L., additional, Zurlo, N., additional, Fujii, K., additional, Otsuka, M., additional, Tanaka, K., additional, Imao, H., additional, Nagashima, Y., additional, Matsuda, Y., additional, Juhász, B., additional, Mohri, A., additional, and Yamazaki, Y., additional

Published
2013
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4. Electron Cyclotron ∕ Bernstein Wave Heating and Current Drive Experiments using Phased-array Antenna in QUEST

Author

Idei, H., primary, Zushi, H., additional, Hanada, K., additional, Nakamura, K., additional, Fujisawa, A., additional, Hasegawa, M., additional, Yoshida, N., additional, Sakamoto, M., additional, Watanebe, H., additional, Tokunaga, K., additional, Nagashima, Y., additional, Ejiri, A., additional, Sakaguchi, M., additional, Kalinnikova, E., additional, Ishiguro, M., additional, Tashima, S., additional, Fukuyama, A., additional, Igami, H., additional, Kubo, S., additional, Sharma, S. K., additional, Ryokai, T., additional, Liu, H. Q., additional, Isobe, M., additional, Nagaoka, K., additional, Nakanishi, H., additional, Nishino, N., additional, Kawasaki, S., additional, Nakashima, H., additional, Higashijima, A., additional, Takase, Y., additional, Maekawa, T., additional, Mitarai, O., additional, Kikuchi, M., additional, Toi, K., additional, Phillips, Cynthia K., additional, and Wilson, James R., additional

Published
2011
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5. Plans for Lower Hybrid Current Drive Experiment using a Dielectric Loaded Waveguide Array Antenna in TST-2

Author

Wakatsuki, T., primary, Ejiri, A., additional, Kakuda, H., additional, Meneghini, O., additional, Shiraiwa, S., additional, Takase, Y., additional, Wright, J. C., additional, Ambo, T., additional, Hanashima, K., additional, Hiratsuka, J., additional, Nagashima, Y., additional, Sakamoto, T., additional, Shino, R., additional, Sonehara, M., additional, Yamaguchi, T., additional, Watanabe, O., additional, Phillips, Cynthia K., additional, and Wilson, James R., additional

Published
2011
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6. Equilibrium Analysis of EC-Sustained and RF-Sustained ST Plasmas

Author

Takase, Y., primary, Ejiri, A., additional, Nagashima, Y., additional, Watanabe, O., additional, An, B. I., additional, Hayashi, H., additional, Hanashima, K., additional, Hiratsuka, J., additional, Kakuda, H., additional, Kobayashi, H., additional, Kurashina, H., additional, Matsuzawa, H., additional, Oosako, T., additional, Sakamoto, T., additional, Wakatsuki, T., additional, Yamada, K., additional, Yamaguchi, T., additional, Bobkov, Volodymyr, additional, and Noterdaeme, Jean-Marie, additional

Published
2009
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8. High Harmonic Fast Wave experiments on TST-2 and UTST

Author

Oosako, T., primary, Kobayashi, H., additional, An, B. I., additional, Kamio, S., additional, Kurashina, H., additional, Hayashi, H., additional, Hihara, R., additional, Matsuzawa, H., additional, Yamada, K., additional, Yamaguchi, T., additional, Imazawa, R., additional, Masuda, T., additional, Nagashima, Y., additional, Yamada, T., additional, Watanabe, O., additional, Inomoto, M., additional, Ejiri, A., additional, Ono, Y., additional, Takase, Y., additional, Bobkov, Volodymyr, additional, and Noterdaeme, Jean-Marie, additional

Published
2009
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9. Physics of Zonal Flows

Author

Itoh, K., primary, Itoh, S.-I., additional, Diamond, P. H., additional, Fujisawa, A., additional, Nagashima, Y., additional, Yagi, M., additional, Fukuyama, A., additional, Hahm, T. S., additional, Hallatschek, K., additional, Tynan, G. R., additional, and Benkadda, Sadruddin, additional

Published
2008
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10. Plasma Curent Start-up Experiment using Waves in the Lower Hybrid Frequency Range in TST-2.

Author

Takase, Y., Wakatsuki, T., Ejiri, A., Kakuda, H., Moeller, C. P., Ambo, T., Hanashima, K., Hiratsuka, J., Kasahara, H., Kumazawa, R., Nagashima, Y., Saito, K., Sakamoto, T., Seki, T., Shimpo, F., Shino, R., Sonehara, M., Watanabe, O., and Yamaguchi, T.

Subjects
PLASMA gases, ELECTRIC currents, RADIO frequency, ELECTRIC displacement, TOKAMAKS, PERMITTIVITY, STATISTICAL bootstrapping, ELECTRONIC excitation, ELECTRON temperature
Abstract

Noninductive plasma current (Ip) start-up experiments using RF power in the lower hybrid frequency range are being conducted on the TST-2 spherical tokamak. The lower hybrid wave (LHW) has demonstrated efficient current drive in conventional tokamaks. However, in spherical tokamak (ST) plasmas with very high dielectric constants (;[variant_greek_epsilon]∼ωpe2/Ωe2>1), accessibility of the LHW to the plasma core is severely limited. Our approach is to keep the plasma density low (such that [variant_greek_epsilon]∼1) during Ip ramp-up. Once Ip reaches a level sufficiently high for neutral beam current drive, plasma can be densified and transformed into an advanced tokamak plasma dominated by the self-driven bootstrap current. Initial plasma start-up experiments were performed on TST-2 using a combline antenna which excites a traveling fast wave. After formation of toroidal flux surfaces, RF power and vertical field were ramped up to increase Ip. Up to 12 kA of Ip has been obtained by this method. Soft X-ray measurements indicate that the electron temperature increases as Ip increases, and hard X-ray spectroscopy indicates that energetic electrons build up as Ip is ramped up. [ABSTRACT FROM AUTHOR]

Published
2011
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11. Electron Cyclotron / Bernstein Wave Heating and Current Drive Experiments using Phased-array Antenna in QUEST.

Author

Idei, H., Zushi, H., Hanada, K., Nakamura, K., Fujisawa, A., Hasegawa, M., Yoshida, N., Sakamoto, M., Watanebe, H., Tokunaga, K., Nagashima, Y., Ejiri, A., Sakaguchi, M., Kalinnikova, E., Ishiguro, M., Tashima, S., Fukuyama, A., Igami, H., Kubo, S., and Sharma, S. K.

Subjects
ELECTRON cyclotron resonance sources, ELECTRIC heating, ELECTROMAGNETIC waves, PHYSICS experiments, PHASED array antennas, PLASMA injection, PERFORMANCE evaluation, ELECTRIC discharges
Abstract

The phased-array antenna system for Electron Cyclotron/Bernstein Wave Heating and Current Drive experiments has been developed in the QUEST. The antenna was designed to excite a pure O-mode wave in the oblique injection for the O-X-B mode conversion experiments, and its good performances were confirmed at a low power level. The plasma current (<∼15 kA) with an aspect ratio of 1.5 was started up and sustained by only RF injection in the low-density operations. The long pulse discharge of 10 kA was also attained for 37 s. The new density window to sustain the plasma current was observed in the high-density plasmas. The single-null divertor configuration with the high plasma current (<∼25 kA) was attained in the 17 s plasma sustainment. [ABSTRACT FROM AUTHOR]

Published
2011
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12. A study of elastic and inelastic collisions of 58Ni+90,94Zr at two near-barrier energies

Author

Corradi, L., primary, Napoli, D. R., additional, Stefanini, A. M., additional, Signorini, C., additional, Sugiyama, Y., additional, Ikezoe, H., additional, Tomita, Y., additional, Ideno, K., additional, Kim, H. J., additional, Nagashima, Y., additional, Masuda, T., additional, Fujiwara, H., additional, Pu, Ye Hu, additional, Tagishi, Y., additional, Sugimitsu, T., additional, and Qi, B., additional

Published
1992
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