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36 results on '"Igami, H."'

1. Isotope effects on transport in LHD

Author

Tanaka, K, primary, Nagaoka, K, additional, Ida, K, additional, Yamada, H, additional, Kobayashi, T, additional, Satake, S, additional, Nakata, M, additional, Kinoshita, T, additional, Ohtani, Y, additional, Tokuzawa, T, additional, Takahashi, H, additional, Warmer, F, additional, Mukai, K, additional, Murakami, S, additional, Sakamoto, R, additional, Nakano, H, additional, Osakabe, M, additional, Morisaki, T, additional, Nunami, M, additional, Tala, T, additional, Tsujimura, T, additional, Takemura, Y, additional, Yokoyama, M, additional, Seki, R, additional, Igami, H, additional, Yoshimura, Y, additional, Kubo, S, additional, Shimozuma, T, additional, Akiyama, T, additional, Yamada, I, additional, Yasuhara, R, additional, Funaba, H, additional, Yoshinuma, M, additional, Goto, M, additional, Oishi, T, additional, Morita, S, additional, Motojima, G, additional, Shoji, M, additional, Masuzaki, S, additional, Michael, C A, additional, and Vacheslavov, L N, additional

Published
2021
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3. First observation and interpretation of spontaneous collective radiation from fusion-born ions in a stellarator plasma.

Author

Reman, B C G, Dendy, R O, Igami, H, Akiyama, T, Salewski, M, Chapman, S C, Cook, J W S, Inagaki, S, Saito, K, Seki, R, Toida, M, Kim, M H, Thatipamula, S G, and Yun, G S

Subjects
DEUTERIUM plasma, CYLINDRICAL plasmas, ION beams, PLASMA confinement, RADIATION, THERMAL plasmas, DEUTERIUM
Abstract

During bursty MHD events, transient ion cyclotron emission (ICE) is observed from deuterium plasmas in the large helical device (LHD) heliotron-stellarator. Unusually, the frequencies of the successive ICE spectral peaks are not close to integer multiples of the local cyclotron frequency of an energetic ion population in the likely emitting region. We show that this ICE is probably driven by a subset of the fusion-born protons near their birth energy E H = 3.02 MeV. This subset has a kinetic energy component parallel to the magnetic field, m H v ∥ 2 / 2 , significantly greater than its perpendicular energy m H v ⊥ 2 / 2 , for which v ⊥ ∼ V A , the AlfvĂ©n speed. First principles computations of the collective relaxation of this proton population, within a majority thermal deuterium plasma, are carried out using a particle-in-cell approach. This captures the full gyro-orbit kinetics of all ions which, together with an electron fluid, evolve self-consistently with the electric and magnetic fields under the Maxwellâ€"Lorentz equations. The simulated ICE spectra are derived from the Fourier transform of the fields which are excited. We find substantial frequency shifts in the peaks of the simulated ICE spectra, which correspond closely to the measured ICE spectra following the resonance condition ω = k ∥ v ∥ + n Ω H for n th proton harmonic. This suggests that the transient ICE in LHD is generated by the identified subset of the fusion-born protons, relaxing under the magnetoacoustic cyclotron instability. So far as is known, this is the first report of a collective radiation signal from fusion-born ions in anon-tokamak magnetically confined plasma. Disambiguation between two or more energetic ion species that could potentially generate complex observed ICE spectra is an increasing challenge, and the results and methodology developed here will assist this. Our approach is also expected to be relevant to ICE driven by ion beams with lower parallel velocities, for example in cylindrical plasma experiments. [ABSTRACT FROM AUTHOR]

Published
2022
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4. Improved performance of electron cyclotron resonance heating by perpendicular injection in the Large Helical Device

Author

Tsujimura, T.I., primary, Yanai, R., additional, Mizuno, Y., additional, Tanaka, K., additional, Yoshimura, Y., additional, Tokuzawa, T., additional, Nishiura, M., additional, Sakamoto, R., additional, Motojima, G., additional, Kubo, S., additional, Shimozuma, T., additional, Igami, H., additional, Takahashi, H., additional, Yoshinuma, M., additional, and Ohshima, S., additional

Published
2020
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5. Isotope effect in transient electron thermal transport property and its impact on the electron internal transport barrier formation in LHD

Author

Kobayashi, T., primary, Ida, K., additional, Tanaka, K., additional, Yoshinuma, M., additional, Tsujimura, T.Ii, additional, Inagaki, S., additional, Tokuzawa, T., additional, Tsuchiya, H., additional, Tamura, N., additional, Igami, H., additional, Yoshimura, Y., additional, Itoh, S.-I., additional, Itoh, K., additional, and Experiment Group, LHD, additional

Published
2020
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6. Collective Thomson scattering with 77, 154, and 300 GHz sources in LHD

Author

Nishiura, M., primary, Tanaka, K., additional, Kubo, S., additional, Saito, T., additional, Kenmochi, N., additional, Nuga, H., additional, Seki, R., additional, Shimozuma, T., additional, Yoshimura, Y., additional, Igami, H., additional, Takahashi, H., additional, Tsujimura, T.I., additional, Yanai, R., additional, and Tatematsu, Y., additional

Published
2020
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7. Correcting for non-periodic behaviour in perturbative experiments: application to heat pulse propagation and modulated gas-puff experiments

Author

van Berkel, M., van Kampen, R.J. R., Vandersteen, G., Kobayashi, T., Ravensbergen, T., Igami, H., Lammers, J.T., Oosterwegel, G., Galperti, C., Felici, F., de Baar, M.R., Group, LHDExperiment, team, TCV, Control Systems Technology, Group Heemels, Applied Physics and Science Education, Science and Technology of Nuclear Fusion, and Electricity

Subjects
perturbative experiments, Radiation, 01 natural sciences, gas puff, 010305 fluids & plasmas, power, symbols.namesake, Quality (physics), 0103 physical sciences, Initial value problem, electron transport, 010306 general physics, Physics, Divertor, System identification, local polynomial method, Mechanics, Condensed Matter Physics, Fourier analysis, Core (optical fiber), Fourier transform, Nuclear Energy and Engineering, transport, detachment, symbols, identification, systems
Abstract

This paper introduces a recent innovation in dealing with non-periodic behavior often referred to as transients in perturbative experiments. These transients can be the result from the unforced response due to the initial condition and other slow trends in the measurement data and are a source of error when performing and interpreting Fourier spectra. Fourier analysis is particularly relevant in system identification used to build feedback controllers and the analysis of various pulsed experiments such as heat pulse propagation studies. The basic idea behind the methodology is that transients are continuous complex-valued smooth functions in the Fourier domain which can be estimated from the Fourier data. Then, these smooth functions can be subtracted from the data such that only periodic components are retained. The merit of the approach is shown in two experimental examples, i.e. heat pulse propagation (core transport analysis) and radiation front movement due to gas puffing in the divertor. The examples show that the quality of the data is significantly improved such that it allows for new interpretation of the results even for non-ideal measurements.

Published
2020

8. Isotope effects on energy, particle transport and turbulence in electron cyclotron resonant heating plasma of the Large Helical Device

Author

Tanaka, K., primary, Ohtani, Y., additional, Nakata, M., additional, Warmer, F., additional, Tsujimura, T., additional, Takemura, Y., additional, Kinoshita, T., additional, Takahashi, H., additional, Yokoyama, M., additional, Seki, R., additional, Igami, H., additional, Yoshimura, Y., additional, Kubo, S., additional, Shimozuma, T., additional, Tokuzawa, T., additional, Akiyama, T., additional, Yamada, I., additional, Yasuhara, R., additional, Funaba, H., additional, Yoshinuma, M., additional, Ida, K., additional, Goto, M., additional, Motojima, G., additional, Shoji, M., additional, Masuzaki, S., additional, Michael, C.A., additional, Vacheslavov, L.N., additional, Osakabe, M., additional, and Morisaki, T., additional

Published
2019
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10. Improved performance of electron cyclotron resonance heating by perpendicular injection in the Large Helical Device.

Author

Tsujimura, T.I., Yanai, R., Mizuno, Y., Tanaka, K., Yoshimura, Y., Tokuzawa, T., Nishiura, M., Sakamoto, R., Motojima, G., Kubo, S., Shimozuma, T., Igami, H., Takahashi, H., Yoshinuma, M., Ohshima, S., and Group, The LHD Experiment

Subjects
CYCLOTRON resonance, ELECTRON cyclotron resonance heating, ELECTRON density, CYCLOTRONS
Abstract

A real-time interlock system for power injection in electron cyclotron resonance heating (ECRH) was developed to be applied to Large Helical Device (LHD) plasma. This system enabled perpendicular injection, thus improving the performance of ECRH more than has ever been achieved before in LHD. Perpendicular propagation of the electron cyclotron wave at 77 GHz became more insensitive to the effect of refraction in comparison to the conventional oblique propagation. The achieved central electron temperature in the case of perpendicular injection was approximately 2 keV higher than that in the case of standard oblique injection for a central electron density of 1 × 1019 m−3 by 1 MW injection. With such improved performance of ECRH, high-density ECRH plasma of 8 × 1019 m−3 was successfully sustained after the injection of multiple hydrogen ice pellets for the first time in LHD. [ABSTRACT FROM AUTHOR]

Published
2021
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11. Extended investigations of isotope effects on ECRH plasma in LHD.

Author

Tanaka, K., Nakata, M., Ohtani, Y., Tokuzawa, T., Yamada, H., Warmer, F., Nunami, M., Satake, S., Tala, T., Tsujimura, T., Takemura, Y., Kinoshita, T., Takahashi, H., Yokoyama, M., Seki, R., Igami, H., Yoshimura, Y., Kubo, S., Shimozuma, T., and Akiyama, T.

Subjects
PLASMA turbulence, ISOTOPES, INVESTIGATIONS, ELECTRON transport, ION temperature
Abstract

Isotope effects of ECRH plasma in LHD were investigated in detail. A clear difference of transport and turbulence characteristics in H and D plasmas was found in the core region, with normalized radius ρ < 0.8 in high collisionality regime. On the other hand, differences of transport and turbulence were relatively small in low collisionality regime. Power balance analysis and neoclassical calculation showed a reduction of the anomalous contribution to electron and ion transport in D plasma compared with H plasma in the high collisionality regime. In core region, density modulation experiments also showed more reduced particle diffusion in D plasma than in H plasma, in the high collisionality regime. Ion scale turbulence was clearly reduced at ρ < 0.8 in high collisionality regime in D plasma compared with H plasma. The gyrokinetic linear analyses showed that the dominant instability ρ = 0.5 and 0.8 were ion temperature gradient mode (ITG). The linear growth rate of ITG was reduced in D plasma than in H plasma in high collisionality regime. This is due to the lower normalized ITG and density gradient. More hollowed density profile in D plasma is likely to be the key control parameter. Present analyses suggest that anomalous process play a role to make hollower density profiles in D plasma rather than neoclassical process. Electron scale turbulence were also investigated from the measurements and linear gyrokinetic simulations. [ABSTRACT FROM AUTHOR]

Published
2020
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12. Extension of the operational regime of the LHD towards a deuterium experiment

Author

Takeiri, Y., primary, Morisaki, T., additional, Osakabe, M., additional, Yokoyama, M., additional, Sakakibara, S., additional, Takahashi, H., additional, Nakamura, Y., additional, Oishi, T., additional, Motojima, G., additional, Murakami, S., additional, Ito, K., additional, Ejiri, A., additional, Imagawa, S., additional, Inagaki, S., additional, Isobe, M., additional, Kubo, S., additional, Masamune, S., additional, Mito, T., additional, Murakami, I., additional, Nagaoka, K., additional, Nagasaki, K., additional, Nishimura, K., additional, Sakamoto, M., additional, Sakamoto, R., additional, Shimozuma, T., additional, Shinohara, K., additional, Sugama, H., additional, Watanabe, K.Y., additional, Ahn, J.W., additional, Akata, N., additional, Akiyama, T., additional, Ashikawa, N., additional, Baldzuhn, J., additional, Bando, T., additional, Bernard, E., additional, Castejón, F., additional, Chikaraishi, H., additional, Emoto, M., additional, Evans, T., additional, Ezumi, N., additional, Fujii, K., additional, Funaba, H., additional, Goto, M., additional, Goto, T., additional, Gradic, D., additional, Gunsu, Y., additional, Hamaguchi, S., additional, Hasegawa, H., additional, Hayashi, Y., additional, Hidalgo, C., additional, Higashiguchi, T., additional, Hirooka, Y., additional, Hishinuma, Y., additional, Horiuchi, R., additional, Ichiguchi, K., additional, Ida, K., additional, Ido, T., additional, Igami, H., additional, Ikeda, K., additional, Ishiguro, S., additional, Ishizaki, R., additional, Ishizawa, A., additional, Ito, A., additional, Ito, Y., additional, Iwamoto, A., additional, Kamio, S., additional, Kamiya, K., additional, Kaneko, O., additional, Kanno, R., additional, Kasahara, H., additional, Kato, D., additional, Kato, T., additional, Kawahata, K., additional, Kawamura, G., additional, Kisaki, M., additional, Kitajima, S., additional, Ko, W.H., additional, Kobayashi, M., additional, Kobayashi, S., additional, Kobayashi, T., additional, Koga, K., additional, Kohyama, A., additional, Kumazawa, R., additional, Lee, J.H., additional, López-Bruna, D., additional, Makino, R., additional, Masuzaki, S., additional, Matsumoto, Y., additional, Matsuura, H., additional, Mitarai, O., additional, Miura, H., additional, Miyazawa, J., additional, Mizuguchi, N., additional, Moon, C., additional, Morita, S., additional, Moritaka, T., additional, Mukai, K., additional, Muroga, T., additional, Muto, S., additional, Mutoh, T., additional, Nagasaka, T., additional, Nagayama, Y., additional, Nakajima, N., additional, Nakanishi, H., additional, Nakano, H., additional, Nakata, M., additional, Narushima, Y., additional, Nishijima, D., additional, Nishimura, A., additional, Nishimura, S., additional, Nishitani, T., additional, Nishiura, M., additional, Nobuta, Y., additional, Noto, H., additional, Nunami, M., additional, Obana, T., additional, Ogawa, K., additional, Ohdachi, S., additional, Ohno, M., additional, Ohno, N., additional, Ohtani, H., additional, Okamoto, M., additional, Oya, Y., additional, Ozaki, T., additional, Peterson, B.J., additional, Preynas, M., additional, Sagara, S., additional, Saito, K., additional, Sakaue, H., additional, Sanpei, A., additional, Satake, S., additional, Sato, M., additional, Saze, T., additional, Schmitz, O., additional, Seki, R., additional, Seki, T., additional, Sharov, I., additional, Shimizu, A., additional, Shiratani, M., additional, Shoji, M., additional, Skinner, C., additional, Soga, R., additional, Stange, T., additional, Suzuki, C., additional, Suzuki, Y., additional, Takada, S., additional, Takahata, K., additional, Takayama, A., additional, Takayama, S., additional, Takemura, Y., additional, Takeuchi, Y., additional, Tamura, H., additional, Tamura, N., additional, Tanaka, H., additional, Tanaka, K., additional, Tanaka, M., additional, Tanaka, T., additional, Tanaka, Y., additional, Toda, S., additional, Todo, Y., additional, Toi, K., additional, Toida, M., additional, Tokitani, M., additional, Tokuzawa, T., additional, Tsuchiya, H., additional, Tsujimura, T., additional, Tsumori, K., additional, Usami, S., additional, Velasco, J.L., additional, Wang, H., additional, Watanabe, T.-H., additional, Watanabe, T., additional, Yagi, J., additional, Yajima, M., additional, Yamada, H., additional, Yamada, I., additional, Yamagishi, O., additional, Yamaguchi, N., additional, Yamamoto, Y., additional, Yanagi, N., additional, Yasuhara, R., additional, Yatsuka, E., additional, Yoshida, N., additional, Yoshinuma, M., additional, Yoshimura, S., additional, and Yoshimura, Y., additional

Published
2017
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13. Analysis of higher harmonics on bidirectional heat pulse propagation experiment in helical and tokamak plasmas

Author

Kobayashi, T., primary, Ida, K., additional, Inagaki, S., additional, Tsuchiya, H., additional, Tamura, N., additional, Choe, G.H., additional, Yun, G.S., additional, Park, H.K., additional, Ko, W.H., additional, Evans, T.E., additional, Austin, M.E., additional, Shafer, M.W., additional, Ono, M., additional, López-bruna, D., additional, Ochando, M.A., additional, Estrada, T., additional, Hidalgo, C., additional, Moon, C., additional, Igami, H., additional, Yoshimura, Y., additional, Tsujimura, T.Ii., additional, Itoh, S.-I., additional, and Itoh, K., additional

Published
2017
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15. Progress of long pulse discharges by ECH in LHD

Author

Yoshimura, Y., primary, Kasahara, H., additional, Tokitani, M., additional, Sakamoto, R., additional, Ueda, Y., additional, Ito, S., additional, Okada, K., additional, Kubo, S., additional, Shimozuma, T., additional, Igami, H., additional, Takahashi, H., additional, Tsujimura, T.I., additional, Makino, R., additional, Kobayashi, S., additional, Mizuno, Y., additional, Akiyama, T., additional, Ashikawa, N., additional, Masuzaki, S., additional, Motojima, G., additional, Shoji, M., additional, Suzuki, C., additional, Tanaka, H., additional, Tanaka, K., additional, Tokuzawa, T., additional, Tsuchiya, H., additional, Yamada, I., additional, Goto, Y., additional, Yamada, H., additional, Mutoh, T., additional, Komori, A., additional, and Takeiri, Y., additional

Published
2016
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16. Development and application of a ray-tracing code integrating with 3D equilibrium mapping in LHD ECH experiments

Author

Ii Tsujimura, T., primary, Kubo, S., additional, Takahashi, H., additional, Makino, R., additional, Seki, R., additional, Yoshimura, Y., additional, Igami, H., additional, Shimozuma, T., additional, Ida, K., additional, Suzuki, C., additional, Emoto, M., additional, Yokoyama, M., additional, Kobayashi, T., additional, Moon, C., additional, Nagaoka, K., additional, Osakabe, M., additional, Kobayashi, S., additional, Ito, S., additional, Mizuno, Y., additional, Okada, K., additional, Ejiri, A., additional, and Mutoh, T., additional

Published
2015
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17. Integrated discharge scenario for high-temperature helical plasma in LHD

Author

Nagaoka, K., primary, Takahashi, H., additional, Murakami, S., additional, Nakano, H., additional, Takeiri, Y., additional, Tsuchiya, H., additional, Osakabe, M., additional, Ida, K., additional, Yokoyama, M., additional, Yoshinuma, M., additional, Morita, S., additional, Goto, M., additional, Oishi, T., additional, Pablant, N., additional, Fujii, K., additional, Tanaka, K., additional, Tamura, N., additional, Nakamura, Y., additional, Du, X., additional, Ido, T., additional, Shimizu, A., additional, Kubo, S., additional, Igami, H., additional, Seki, R., additional, Suzuki, C., additional, Suzuki, Y., additional, Tsumori, K., additional, Ikeda, K., additional, Kisaki, M., additional, Yoshimura, Y., additional, Shimozuma, T., additional, Seki, T., additional, Saito, K., additional, Kasahara, H., additional, Kamio, S., additional, Mutoh, T., additional, Kaneko, O., additional, Yamada, H., additional, and Komori, A., additional

Published
2015
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18. Development of gyrotrons for fusion with power exceeding 1 MW over a wide frequency range

Author

Kariya, T., primary, Imai, T., additional, Minami, R., additional, Numakura, T., additional, Eguchi, T., additional, Kato, T., additional, Endo, Y., additional, Ichimura, M., additional, Shimozuma, T., additional, Kubo, S., additional, Takahashi, H., additional, Yoshimura, Y., additional, Igami, H., additional, Ito, S., additional, Mutoh, T., additional, Sakamoto, K., additional, Idei, H., additional, Zushi, H., additional, Nagasaki, K., additional, Sano, F., additional, Ono, M., additional, and Mitsunaka, Y., additional

Published
2015
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19. Overview of transport and MHD stability study: focusing on the impact of magnetic field topology in the Large Helical Device

Author

Ida, K., Nagaoka, K., Inagaki, S., Kasahara, H., Evans, T., Yoshinuma, M., Kamiya, K., Ohdach, S., Osakabe, M., Kobayashi, M., Sudo, S., Itoh, K., Akiyama, T., Emoto, M., Dinklage, A., Du, X., Fujii, K., Goto, M., Goto, T., Hasuo, M., Hidalgo, C., Ichiguchi, K., Ishizawa, A., Jakubowski, M., Kawamura, G., Kato, D., Morita, S., Mukai, K., Murakami, I., Murakami, S., Narushima, Y., Nunami, M., Ohno, N., Pablant, N., Sakakibara, S., Seki, T., Shimozuma, T., Shoji, M., Tanaka, K., Tokuzawa, T., Todo, Y., Wang, H., Yokoyama, M., Yamada, H., Takeiri, Y., Mutoh, T., Imagawa, S., Mito, T., Nagayama, Y., Watanabe, K.Y., Ashikawa, N., Chikaraishi, H., Ejiri, A., Furukawa, M., Fujita, T., Hamaguchi, S., Igami, H., Isobe, M., Masuzaki, S., Morisaki, T., Motojima, G., Nagasaki, K., Nakano, H., Oya, Y., Suzuki, C., Suzuki, Y., Sakamoto, R., Sakamoto, M., Sanpei, A., Takahashi, H., Tsuchiya, H., Tokitani, M., Ueda, Y., Yoshimura, Y., Yamamoto, S., Nishimura, K., Sugama, H., Yamamoto, T., Idei, H., Isayama, A., Kitajima, S., Masamune, S., Shinohara, K., Bawankar, P.S., Bernard, E., von Berkel, M., Funaba, H., Huang, X.L., Ii, T., Ido, T., Ikeda, K., Kamio, S., Kumazawa, R., Kobayashi, T., Moon, C., Muto, S., Miyazawa, J., Ming, T., Nakamura, Y., Nishimura, S., Ogawa, K., Ozaki, T., Oishi, T., Ohno, M., Pandya, S., Shimizu, A., Seki, R., Sano, R., Saito, K., Sakaue, H., Takemura, Y., Tsumori, K., Tamura, N., Tanaka, H., Toi, K., Wieland, B., Yamada, I., Yasuhara, R., Zhang, H., Kaneko, O., Komori, A., and Collaborators

Subjects
Nuclear and High Energy Physics, Electron density, topology, Materials science, Plasma, Electron, Condensed Matter Physics, Topology, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, Ion, Magnetic field, Momentum, Large Helical Device, transport, 0103 physical sciences, Atomic physics, Magnetohydrodynamics, 010306 general physics, helical
Abstract

The progress in the understanding of the physics and the concurrent parameter extension in the large helical device since the last IAEA-FEC, in 2012 (Kaneko O et al 2013 Nucl. Fusion 53 095024), is reviewed. Plasma with high ion and electron temperatures (Ti(0) ~ Te(0) ~ 6 keV) with simultaneous ion and electron internal transport barriers is obtained by controlling recycling and heating deposition. A sign flip of the nondiffusive term of impurity/momentum transport (residual stress and convection flow) is observed, which is associated with the formation of a transport barrier. The impact of the topology of three-dimensional magnetic fields (stochastic magnetic fields and magnetic islands) on heat momentum, particle/impurity transport and magnetohydrodynamic stability is also discussed. In the steady state operation, a 48 min discharge with a line-averaged electron density of 1 × 1019 m−3 and with high electron and ion temperatures (Ti(0) ~ Te(0) ~ 2 keV), resulting in 3.36 GJ of input energy, is achieved.

Published
2015

21. Feedback control of ECRH polarization on LHD

Author

Felici, F., primary, Shimozuma, T., additional, Kubo, S., additional, Yoshimura, Y., additional, Takahashi, H., additional, Igami, H., additional, Goodman, T.P., additional, Seki, T., additional, Tsuchiya, H., additional, Ito, S., additional, Mizuno, Y., additional, Sauter, O., additional, and Mutoh, T., additional

Published
2010
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22. Development of net-current free heliotron plasmas in the Large Helical Device

Author

Komori, A., primary, Yamada, H., additional, Sakakibara, S., additional, Kaneko, O., additional, Kawahata, K., additional, Mutoh, T., additional, Ohyabu, N., additional, Imagawa, S., additional, Ida, K., additional, Nagayama, Y., additional, Shimozuma, T., additional, Watanabe, K.Y., additional, Mito, T., additional, Kobayashi, M., additional, Nagaoka, K., additional, Sakamoto, R., additional, Yoshida, N., additional, Ohdachi, S., additional, Ashikawa, N., additional, Feng, Y., additional, Fukuda, T., additional, Igami, H., additional, Inagaki, S., additional, Kasahara, H., additional, Kubo, S., additional, Kumazawa, R., additional, Mitarai, O., additional, Murakami, S., additional, Nakamura, Yuji, additional, Nishiura, M., additional, Hino, T., additional, Masuzaki, S., additional, Tanaka, K., additional, Toi, K., additional, Weller, A., additional, Yoshinuma, M., additional, Narushima, Y., additional, Ohno, N., additional, Okamura, T., additional, Tamura, N., additional, Saito, K., additional, Seki, T., additional, Sudo, S., additional, Tanaka, H., additional, Tokuzawa, T., additional, Yanagi, N., additional, Yokoyama, M., additional, Yoshimura, Y., additional, Akiyama, T., additional, Chikaraishi, H., additional, Chowdhuri, M., additional, Emoto, M., additional, Ezumi, N., additional, Funaba, H., additional, Garcia, L., additional, Goncharov, P., additional, Goto, M., additional, Ichiguchi, K., additional, Ichimura, M., additional, Idei, H., additional, Ido, T., additional, Iio, S., additional, Ikeda, K., additional, Irie, M., additional, Isayama, A., additional, Ishigooka, T., additional, Isobe, M., additional, Ito, T., additional, Itoh, K., additional, Iwamae, A., additional, Hamaguchi, S., additional, Hamajima, T., additional, Kitajima, S., additional, Kado, S., additional, Kato, D., additional, Kato, T., additional, Kobayashi, S., additional, Kondo, K., additional, Masamune, S., additional, Matsumoto, Y., additional, Matsunami, N., additional, Minami, T., additional, Michael, C., additional, Miura, H., additional, Miyazawa, J., additional, Mizuguchi, N., additional, Morisaki, T., additional, Morita, S., additional, Motojima, G., additional, Murakami, I., additional, Muto, S., additional, Nagasaki, K., additional, Nakajima, N., additional, Nakamura, Y., additional, Nakanishi, H., additional, Nakano, H., additional, Narihara, K., additional, Nishimura, A., additional, Nishimura, H., additional, Nishimura, K., additional, Nishimura, S., additional, Nishino, N., additional, Notake, T., additional, Obana, T., additional, Ogawa, K., additional, Oka, Y., additional, Ohishi, T., additional, Okada, H., additional, Okuno, K., additional, Ono, K., additional, Osakabe, M., additional, Osako, T., additional, Ozaki, T., additional, Peterson, B.J., additional, Sakaue, H., additional, Sasao, M., additional, Satake, S., additional, Sato, K., additional, Sato, M., additional, Shimizu, A., additional, Shiratani, M., additional, Shoji, M., additional, Sugama, H., additional, Suzuki, C., additional, Suzuki, Y., additional, Takahata, K., additional, Takahashi, H., additional, Takase, Y., additional, Takeiri, Y., additional, Takenaga, H., additional, Toda, S., additional, Todo, Y., additional, Tokitani, M., additional, Tsuchiya, H., additional, Tsumori, K., additional, Urano, H., additional, Veshchev, E., additional, Watanabe, F., additional, Watanabe, T., additional, Watanabe, T.H., additional, Yamada, I., additional, Yamada, S., additional, Yamagishi, O., additional, Yamaguchi, S., additional, Yoshimura, S., additional, Yoshinaga, T., additional, and Motojima, O., additional

Published
2009
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23. Core electron temperature rise due to Ar gas-puff in EC-heated LHD plasmas

Author

Tamura, N, primary, Inagaki, S, additional, Ida, K, additional, Tanaka, K, additional, Michael, C, additional, Tokuzawa, T, additional, Yamada, I, additional, Narihara, K, additional, Shimozuma, T, additional, Kubo, S, additional, Igami, H, additional, Fukuda, T, additional, Itoh, K, additional, Nagayama, Y, additional, Kawahata, K, additional, Sudo, S, additional, Komori, A, additional, and Team, the LHD, additional

Published
2008
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24. Steady-state operation and high energy particle production of MeV energy in the Large Helical Device

Author

Mutoh, T., primary, Kumazawa, R., additional, Seki, T., additional, Saito, K., additional, Kasahara, H., additional, Nakamura, Y., additional, Masuzaki, S., additional, Kubo, S., additional, Takeiri, Y., additional, Shimozuma, T., additional, Yoshimura, Y., additional, Igami, H., additional, Watanabe, T., additional, Ogawa, H., additional, Miyazawa, J., additional, Shoji, M., additional, Ashikawa, N., additional, Nishimura, K., additional, Osakabe, M., additional, Tsumori, K., additional, Ikeda, K., additional, Nagaoka, K., additional, Oka, Y., additional, Chikaraishi, H., additional, Funaba, H., additional, Morita, S., additional, Goto, M., additional, Inagaki, S., additional, Narihara, K., additional, Tokuzawa, T., additional, Sakamoto, R., additional, Morisaki, T., additional, Peterson, B.J., additional, Tanaka, K., additional, Nakanishi, H., additional, Nishiura, M., additional, Ozaki, T., additional, Shimpo, F., additional, Nomura, G., additional, Takahashi, C., additional, Yokota, M., additional, Zhao, Y.P., additional, Kwak, J.G., additional, Murakami, S., additional, Okada, H., additional, Yamada, H., additional, Kawahata, K., additional, Ohyabu, N., additional, Kaneko, O., additional, Ida, K., additional, Nagayama, Y., additional, Watanabe, K.Y., additional, Noda, N., additional, Komori, A., additional, Sudo, S., additional, and Motojima, O., additional

Published
2007
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25. Long-pulse plasma discharge on the Large Helical Device

Author

Kumazawa, R, primary, Mutoh, T, additional, Saito, K, additional, Seki, T, additional, Nakamura, Y, additional, Kubo, S, additional, Shimozuma, T, additional, Yoshimura, Y, additional, Igami, H, additional, Ohkubo, K, additional, Takeiri, Y, additional, Oka, Y, additional, Tsumori, K, additional, Osakabe, M, additional, Ikeda, K, additional, Nagaoka, K, additional, Kaneko, O, additional, Miyazawa, J, additional, Morita, S, additional, Narihara, K, additional, Shoji, M, additional, Masuzaki, S, additional, Kobayashi, M, additional, Ogawa, H, additional, Goto, M, additional, Morisaki, T, additional, Peterson, B.J, additional, Sato, K, additional, Tokuzawa, T, additional, Ashikawa, N, additional, Nishimura, K, additional, Funaba, H, additional, Chikaraishi, H, additional, Watari, T, additional, Watanabe, T, additional, Sakamoto, M, additional, Ichimura, M, additional, Takase, Y, additional, Notake, T, additional, Takeuchi, N, additional, Torii, Y, additional, Shimpo, F, additional, Nomura, G, additional, Takahashi, C, additional, Yokota, M, additional, Kato, A, additional, Zhao, Y, additional, Kwak, J.G, additional, Yoon, J.S, additional, Yamada, H, additional, Kawahata, K, additional, Ohyabu, N, additional, Ida, K, additional, Nagayama, Y, additional, Noda, N, additional, Komori, A, additional, Sudo, S, additional, Motojima, O, additional, and group, LHD experiment, additional

Published
2006
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26. ICRF Heated Long-Pulse Plasma Discharges in LHD

Author

Kumazawa, R, primary, Seki, T, additional, Mutoh, T, additional, Saito, K, additional, Watari, T, additional, Nakamura, Y, additional, Sakamoto, M, additional, Watanabe, T, additional, Kubo, S, additional, Shimozuma, T, additional, Yoshimura, Y, additional, Igami, H, additional, Takeiri, Y, additional, Oka, Y, additional, Tsumori, K, additional, Osakabe, M, additional, Ikeda, K, additional, Nagaoka, K, additional, Kaneko, O, additional, Miyazawa, J, additional, Morita, S, additional, Narihara, K, additional, Shoji, M, additional, Masuzaki, S, additional, Goto, M, additional, Morisaki, T, additional, Peterson, B J, additional, Sato, K, additional, Tokuzawa, T, additional, Ashikawa, N, additional, Nishimura, K, additional, Funaba, H, additional, Chikaraishi, H, additional, Notake, T, additional, Torii, Y, additional, Okada, H, additional, Ichimura, M, additional, Higaki, H, additional, Takase, Y, additional, Kasahara, H, additional, Shimpo, F, additional, Nomura, G, additional, Takahashi, C, additional, Yokota, M, additional, Kato, A, additional, Yanping, Zhao, additional, Yoon, J S, additional, Kwak, J G, additional, Yamada, H, additional, Kawahata, K, additional, Ohyabu, N, additional, Ida, K, additional, Nagayama, Y, additional, Noda, N, additional, Komori, A, additional, Sudo, S, additional, Motojima, O, additional, and Group, the LHD Experimental, additional

Published
2006
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27. Formation of spherical tokamak equilibria by ECH in the LATE device

Author

Maekawa, T, primary, Terumichi, Y, additional, Tanaka, H, additional, Uchida, M, additional, Yoshinaga, T, additional, Yamaguchi, S, additional, Igami, H, additional, Konno, M, additional, Katsuura, K, additional, Hayashi, K, additional, Abe, Y, additional, Yamada, J, additional, Maebara, S, additional, and Imai, T, additional

Published
2005
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28. Overview of confinement and MHD stability in the Large Helical Device

Author

Motojima, O, primary, Ida, K, additional, Watanabe, K.Y, additional, Nagayama, Y, additional, Komori, A, additional, Morisaki, T, additional, Peterson, B.J, additional, Takeiri, Y, additional, Ohkubo, K, additional, Tanaka, K, additional, Shimozuma, T, additional, Inagaki, S, additional, Kobuchi, T, additional, Sakakibara, S, additional, Miyazawa, J, additional, Yamada, H, additional, Ohyabu, N, additional, Narihara, K, additional, Nishimura, K, additional, Yoshinuma, M, additional, Morita, S, additional, Akiyama, T, additional, Ashikawa, N, additional, Beidler, C.D, additional, Emoto, M, additional, Fujita, T, additional, Fukuda, T, additional, Funaba, H, additional, Goncharov, P, additional, Goto, M, additional, Ido, T, additional, Ikeda, K, additional, Isayama, A, additional, Isobe, M, additional, Igami, H, additional, Ishii, K, additional, Itoh, K, additional, Kaneko, O, additional, Kawahata, K, additional, Kawazome, H, additional, Kubo, S, additional, Kumazawa, R, additional, Masuzaki, S, additional, Matsuoka, K, additional, Minami, T, additional, Murakami, S, additional, Muto, S, additional, Mutoh, T, additional, Nakamura, Y, additional, Nakanishi, H, additional, Narushima, Y, additional, Nishiura, M, additional, Nishizawa, A, additional, Noda, N, additional, Notake, T, additional, Nozato, H, additional, Ohdachi, S, additional, Oka, Y, additional, Okajima, S, additional, Osakabe, M, additional, Ozaki, T, additional, Sagara, A, additional, Saida, T, additional, Saito, K, additional, Sakamoto, M, additional, Sakamoto, R, additional, Sakamoto, Y, additional, Sasao, M, additional, Sato, K, additional, Sato, M, additional, Seki, T, additional, Shoji, M, additional, Sudo, S, additional, Takeuchi, N, additional, Takenaga, H, additional, Tamura, N, additional, Toi, K, additional, Tokuzawa, T, additional, Torii, Y, additional, Tsumori, K, additional, Uda, T, additional, Wakasa, A, additional, Watari, T, additional, Yamada, I, additional, Yamamoto, S, additional, Yamazaki, K, additional, Yokoyama, M, additional, and Yoshimura, Y, additional

Published
2005
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29. Achievement of One Hour Discharge with ECH on LHD

Author

Yoshimura, Y, primary, Kubo, S, additional, Shimozuma, T, additional, Igami, H, additional, Mutoh, T, additional, Nakamura, Y, additional, Ohkubo, K, additional, Notake, T, additional, Takita, Y, additional, Kobayashi, S, additional, Ito, S, additional, Mizuno, Y, additional, Inagaki, S, additional, Kojima, M, additional, Kobayashi, M, additional, Sakakibara, S, additional, Tokuzawa, T, additional, Nakanishi, H, additional, Narihara, K, additional, Masuzaki, S, additional, Miyazawa, J, additional, Morisaki, T, additional, Komori, A, additional, Motojima, O, additional, and Group, the LHD Experimental, additional

Published
2005
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32. Electron Bernstein wave heating by electron cyclotron wave injection from the high-field side in LHD.

Author

Yoshimura, Y., Igami, H., Kubo, S., Shimozuma, T., Takahashi, H., Nishiura, M., Ohdachi, S., Tanaka, K., Ida, K., Yoshinuma, M., Suzuki, C., Ogasawara, S., Makino, R., Idei, H., Kumazawa, R., Mutoh, T., and Yamada, H.

Subjects
*PLASMA Bernstein waves, *PLASMA heating, *ELECTRON cyclotron resonance heating, *HELICAL waveguides, *GYROTRONS, *ELECTRON density
Abstract

In the Large Helical Device (LHD), evident electron Bernstein wave (EBW) heating was successfully performed. The experiment was carried out using the electron cyclotron heating (ECH) system that was upgraded by installation of high-power, long-pulse 77 GHz gyrotrons. The EBW heating was achieved by a mode conversion from injected EC wave to EBW by the so-called slow-XB technique where an X-mode wave is injected to the plasma from the high magnetic field side. The specific magnetic configuration of LHD provides a good opportunity to realize the slow-XB technique, which is generally difficult for tokamaks. With the slow-XB technique, increases in kinetically evaluated electron energy Wpe and electron temperature Te were observed in overdense plasmas. An electron heating in the so-called super dense core plasma in LHD, which is characterized with an internal diffusion barrier and a steep density gradient at the plasma core, was successfully demonstrated in the plasma core region where the central electron density ne0 of 17 x 1019 m-3 was about 1.2 times higher, at the beginning of the EC-wave injection, than the left-hand cut-off density of applied 77 GHz EC waves. [ABSTRACT FROM AUTHOR]

Published
2013
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33. Steady-state operation using a dipole mode ion cyclotron heating antenna and 77 GHz electron cyclotron heating in the Large Helical Device.

Author

Mutoh, T., Seki, T., Kumazawa, R., Saito, K., Kasahara, H., Seki, R., Kubo, S., Shimozuma, T., Yoshimura, Y., Igami, H., Takahashi, H., Nishiura, M., Shoji, M., Miyazawa, J., Nakamura, Y., Tokitani, M., Ashikawa, N., Masuzaki, S., Idei, H., and Nomura, G.

Subjects
DIPOLE antennas, STEADY-state flow, HEAT transfer, ELECTRON cyclotron resonance heating, TOKAMAKS, PARTICLES (Nuclear physics)
Abstract

The steady-state operation of high-performance plasmas in the Large Helical Device (LHD) has progressed since the 2010 IAEA Conference in Korea by means of a newly installed ion cyclotron heating (ICH) antenna (HAS antenna) and an improved electron cyclotron heating (ECH) system. The HAS antenna can control the launched parallel wave number and heat the core plasma efficiently in the case of dipole mode operation. Understanding of the physics and technology of wave heating, particle and heat flow balances, and plasma-wall interactions in LHD has also improved. The heating power of steady-state ICH and ECH exceeded 1MWand 500kW, respectively, and a higher density helium plasma with minority hydrogen ions was maintained using the HAS antenna and new 77 GHz gyrotrons. As a result, plasma performance improved, e.g. electron temperature of more than 2 keV at a density of more than 2 × 1019 m-3became possible for more than 1 min. Heat flow balance and particle flux balance of steady-state operation were evaluated. Particle balance analysis indicated that externally fed helium and hydrogen particles were mainly absorbed by the chamber wall and divertor plates, even after the 54 min operation. [ABSTRACT FROM AUTHOR]

Published
2013
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34. Development of multi-purpose MW gyrotrons for fusion devices.

Author

Minami, R., Kariya, T., Imai, T., Numakura, T., Endo, Y., Nakabayashi, H., Eguchi, T., Shimozuma, T., Kubo, S., Yoshimura, Y., Igami, H., Takahashi, H., Mutoh, T., Ito, S., Idei, H., Zushi, H., Yamaguchi, Y., Sakamoto, K., and Mitsunaka, Y.

Subjects
GYROTRONS, FUSION reactors, TECHNICAL specifications, HIGH-density plasmas, PLASMA heating
Abstract

The latest development achievements in the University of Tsukuba of over-1MW power level gyrotrons required in present-day fusion devices, GAMMA 10, Large Helical Device (LHD), QUEST, Heliotron J and NSTX, are presented. The obtained maximum outputs are 1.9MW for 0.1 s on the 77 GHz LHD tube and 1.2MW for 1ms on the 28 GHzGAMMA10 one, which are new records in these frequency ranges. In long-pulse operation, 0.3MWfor 40 min at 77 GHz and 0.54MW for 2 s at 28 GHz are achieved. A new programme of 154 GHz 1MW development has started for high-density plasma heating in LHD. On the first 154 GHz tube, 1.0MW for 1 s is achieved. As a next activity of the 28 GHz gyrotron, an over-1.5MW gyrotron is designed and fabricated to study the multi-MW oscillation. The possibility of 0.4MWcontinuous wave and 2MWlevel output in operations of a few seconds, after the improvements of output window and mode converter, is shown. Moreover, a new design study of dual-frequency gyrotron at 28 and 35 GHz has started, which indicates the practicability of the multi-purpose gyrotron. [ABSTRACT FROM AUTHOR]

Published
2013
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