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491 results on '"Funaba, H."'

1. Initial operation and data processing on a system for real-time evaluation of Thomson scattering signals on the Large Helical Device

Author

Hammond, K. C., Laggner, F. M., Diallo, A., Doskoczynski, S., Freeman, C., Funaba, H., Gates, D. A., Rozenblat, R., Tchilinguirian, G., Xing, Z., Yamada, I., Yasuhara, R., Zimmer, G., and Kolemen, E.

Subjects
Physics - Plasma Physics
Abstract

A scalable system for real-time analysis of electron temperature and density based on signals from the Thomson scattering diagnostic, initially developed for and installed on the NSTX-U experiment, was recently adapted for the Large Helical Device (LHD) and operated for the first time during plasma discharges. During its initial operation run, it routinely recorded and processed signals for four spatial points at the laser repetition rate of 30 Hz, well within the system's rated capability for 60 Hz. We present examples of data collected from this initial run and describe subsequent adaptations to the analysis code to improve the fidelity of the temperature calculations., Comment: 5 pages, 5 figures

Published
2021
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3. Turbulence Transition in Magnetically Confined Hydrogen and Deuterium Plasmas

Author

Kinoshita, T., primary, Tanaka, K., additional, Ishizawa, A., additional, Sakai, H., additional, Nunami, M., additional, Ohtani, Y., additional, Yamada, H., additional, Sato, M., additional, Nakata, M., additional, Tokuzawa, T., additional, Yasuhara, R., additional, Takemura, Y., additional, Yamada, I., additional, Funaba, H., additional, Ida, K., additional, Yoshinuma, M., additional, Tsujimura, T., additional, Seki, R., additional, Ichiguchi, K., additional, and Michael, C. A., additional

Published
2024
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6. Turbulence Transition in Magnetically Confined Hydrogen and Deuterium Plasmas

Author

Kinoshita, T., Tanaka, K., Ishizawa, A., Sakai, H., Nunami, M., Ohtani, Y., Yamada, H., Sato, M., Nakata, M., Tokuzawa, T., Yasuhara, R., Takemura, Y., Yamada, I., Funaba, H., Ida, K., Yoshinuma, M., Tsujimura, T., Seki, R., Ichiguchi, K., Michael, C. A., Kinoshita, T., Tanaka, K., Ishizawa, A., Sakai, H., Nunami, M., Ohtani, Y., Yamada, H., Sato, M., Nakata, M., Tokuzawa, T., Yasuhara, R., Takemura, Y., Yamada, I., Funaba, H., Ida, K., Yoshinuma, M., Tsujimura, T., Seki, R., Ichiguchi, K., and Michael, C. A.

Abstract

In this study, we discovered a turbulence transition in a large helical device. The turbulence level and turbulence-driven energy transport decrease to a specific transition density and increase above it. The ruling turbulences below and above the transition density were ion-temperature gradient (ITG) and resistive-interchange (RI) turbulences, consistent with the predictions of gyrokinetic theory and two-fluid MHD model, respectively. Isotope experiments on hydrogen (H) and deuterium (D) clarified the role of transitions. In the ITG regime, turbulence levels and energy transport were comparable in the H and D plasmas. In contrast, in the RI regime, they were clearly suppressed in the D plasma. The results provide crucial knowledge for understanding isotope effects and future optimization of stellarator and heliotron devices.

Published
2024

7. Influence of sawtooth oscillations on fast ions in a stellarator

Author

Moseev, D., Zanini, M., Kasahara, H., Laqua, H.P., Funaba, H., Hayashi, W.H.J., Heidbrink, W., Ida, K., Igami, H., Kawamoto, Y., Kenmochi, N., Lazerson, S.A., Nishiura, M., Ochoukov, R., Ogawa, K., Rud, M., Salewski, M., Seki, T., Tamura, N., Tanaka, K., Tokuzawa, T., Yoshinuma, M., Moseev, D., Zanini, M., Kasahara, H., Laqua, H.P., Funaba, H., Hayashi, W.H.J., Heidbrink, W., Ida, K., Igami, H., Kawamoto, Y., Kenmochi, N., Lazerson, S.A., Nishiura, M., Ochoukov, R., Ogawa, K., Rud, M., Salewski, M., Seki, T., Tamura, N., Tanaka, K., Tokuzawa, T., and Yoshinuma, M.

Abstract

Sawtooth oscillations in tokamaks frequently lead to the redistribution of energetic ions, mainly on passing orbits, causing their expulsion from the core. This paper discusses the first measurements of the interaction of fast ions and sawteeth in the Large Helical Device. The crashes were caused by the plasma current induced by Electron Cyclotron Current Drive and Neutral Beam Current Drive. Despite these crashes, there was no detectable redistribution effect on fast ions in either the core or at the edge of the plasma.

Published
2024

9. Estimation of plasma parameter profiles and their derivatives from linear observations by using Gaussian processes

Author

Nishizawa, T, primary, Tokuda, S, additional, Kobayashi, T, additional, Tanaka, K, additional, Funaba, H, additional, Yamada, I, additional, Takemura, Y, additional, Tokuzawa, T, additional, Yasuhara, R, additional, Uehara, H, additional, Ida, K, additional, Takahashi, H, additional, Kawachi, Y, additional, Inagaki, S, additional, Kado, S, additional, Sasaki, M, additional, and Fujisawa, A, additional

Published
2023
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12. Overview of results from the National Spherical Torus Experiment (NSTX)

Author

Gates, DA, Ahn, J, Allain, J, Andre, R, Bastasz, R, Bell, M, Bell, R, Belova, E, Berkery, J, Betti, R, Bialek, J, Biewer, T, Bigelow, T, Bitter, M, Boedo, J, Bonoli, P, Boozer, A, Brennan, D, Breslau, J, Brower, D, Bush, C, Canik, J, Caravelli, G, Carter, M, Caughman, J, Chang, C, Choe, W, Crocker, N, Darrow, D, Delgado-Aparicio, L, Diem, S, D'Ippolito, D, Domier, C, Dorland, W, Efthimion, P, Ejiri, A, Ershov, N, Evans, T, Feibush, E, Fenstermacher, M, Ferron, J, Finkenthal, M, Foley, J, Frazin, R, Fredrickson, E, Fu, G, Funaba, H, Gerhardt, S, Glasser, A, Gorelenkov, N, Grisham, L, Hahm, T, Harvey, R, Hassanein, A, Heidbrink, W, Hill, K, Hillesheim, J, Hillis, D, Hirooka, Y, Hosea, J, Hu, B, Humphreys, D, Idehara, T, Indireshkumar, K, Ishida, A, Jaeger, F, Jarboe, T, Jardin, S, Jaworski, M, Ji, H, Jung, H, Kaita, R, Kallman, J, Katsuro-Hopkins, O, Kawahata, K, Kawamori, E, Kaye, S, Kessel, C, Kim, J, Kimura, H, Kolemen, E, Krasheninnikov, S, Krstic, P, Ku, S, Kubota, S, Kugel, H, La Haye, R, Lao, L, LeBlanc, B, Lee, W, Lee, K, Leuer, J, Levinton, F, Liang, Y, Liu, D, Luhmann, N, Maingi, R, Majeski, R, Manickam, J, and Mansfield, D

Subjects
Atomic, Molecular, Nuclear, Particle and Plasma Physics, Fluids & Plasmas
Abstract

The mission of the National Spherical Torus Experiment (NSTX) is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of high harmonic fast-waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance li ∼ 0.4 with strong shaping (κ ∼ 2.7, δ ∼ 0.8) with βN approaching the with-wall β-limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction fNI ∼ 71%. Instabilities driven by super-Alfvénic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvénic. Linear toroidal Alfvén eigenmode thresholds and appreciable fast ion loss during multi-mode bursts are measured and these results are compared with theory. The impact of n > 1 error fields on stability is an important result for ITER. Resistive wall mode/resonant field amplification feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas and coupling of coaxial helicity injection plasmas to ohmic heating ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF. © 2009 IAEA, Vienna.

Published
2009

16. Spatial Distribution Measurement of High Energy Particle using Time-Of-Flight Neutral Particle Energy Analyzer in Large Helical Device

Author

G1/G2 Group, Ozaki, T., Goncharov, P., Murakami, S., Sudo, S., Shoji, M., Emoto, M., Funaba, H., Goto, M., Ida, K., Idei, H., Ikeda, K., Kanko, O., Kawahata, K., Kobuchi, T., Kubo, S., Kumazawa, R., Morita, S., Motojima, O., Muto, S., Mutoh, T., Nagayama, Y., Nakamura, Y., Nakanishi, H., Narihara, K., Noda, N., Ohdachi, S., Ohyabu, N., Oka, Y., Osakabe, M., Peterson, B., Saito, K., Sakakibara, S., Sasao, M., Sato, K., Seki, T., Shimozuma, T., Takeiri, Y., Tanaka, K., Torii, H., Tsumori, K., Watanabe, T., Watari, T., Zanza, V., Bracco, G., Sibio, A., Tilia, B., Stott, Peter E., editor, Wootton, Alan, editor, Gorini, Giuseppe, editor, Sindoni, Elio, editor, and Batani, Dimitri, editor

Published
2002
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17. Direct observation of the non-locality of non-diffusive counter-gradient electron thermal transport during the formation of hollow electron-temperature profiles in the Large Helical Device

Author

Tsujimura, T. I., primary, Kobayashi, T., additional, Tanaka, K., additional, Ida, K., additional, Nagaoka, K., additional, Yoshinuma, M., additional, Yamada, I., additional, Funaba, H., additional, Seki, R., additional, Satake, S., additional, Kinoshita, T., additional, Tokuzawa, T., additional, Kenmochi, N., additional, Igami, H., additional, Mukai, K., additional, Goto, M., additional, and Kawamoto, Y., additional

Published
2022
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18. Publisher’s Note: “Study of detached plasma profile in the divertor simulation experimental module of tandem mirror GAMMA 10/PDX” [AIP Advances 11, 125231 (2021)]

Author

Yoshikawa, M., primary, Kohagura, J., additional, Ezumi, N., additional, Iijima, T., additional, Nojiri, K., additional, Terakado, A., additional, Nakashima, Y., additional, Kariya, T., additional, Numakura, T., additional, Hirata, M., additional, Minami, R., additional, Sakamoto, M., additional, Ichimura, M., additional, Islam, M. S., additional, Shima, Y., additional, Yasuhara, R., additional, Yamada, I., additional, Funaba, H., additional, Minami, T., additional, Kenmochi, N., additional, Kuwahara, D., additional, and van der Meiden, H. J., additional

Published
2022
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20. Study of detached plasma profile in the divertor simulation experimental module of tandem mirror GAMMA 10/PDX

Author

Yoshikawa, M., primary, Kohagura, J., additional, Ezumi, N., additional, Iijima, T., additional, Nojiri, K., additional, Terakado, A., additional, Nakashima, Y., additional, Kariya, T., additional, Numakura, T., additional, Hirata, M., additional, Minami, R., additional, Sakamoto, M., additional, Ichimura, M., additional, Islam, M. S., additional, Shima, Y., additional, Yasuhara, R., additional, Yamada, I., additional, Funaba, H., additional, Minami, T., additional, Kenmochi, N., additional, Kuwahara, D., additional, and van der Meiden, H. J., additional

Published
2021
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22. 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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23. Initial operation and data processing on a system for real-time evaluation of Thomson scattering signals on the Large Helical Device

Author

Hammond, K. C., primary, Laggner, F. M., additional, Diallo, A., additional, Doskoczynski, S., additional, Freeman, C., additional, Funaba, H., additional, Gates, D. A., additional, Rozenblat, R., additional, Tchilinguirian, G., additional, Xing, Z., additional, Yamada, I., additional, Yasuhara, R., additional, Zimmer, G., additional, and Kolemen, E., additional

Published
2021
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26. Control, data acquisition, data analysis and remote participation in LHD

Author

Nagayama, Y., Emoto, M., Nakanishi, H., Sudo, S., Imazu, S., Inagaki, S., Iwata, C., Kojima, M., Nonomura, M., Ohsuna, M., Tsuda, K., Yoshida, M., Chikaraishi, H., Funaba, H., Horiuchi, R., Ishiguro, S., Ito, Y., Kubo, S., Mase, A., Mito, T., Miyazawa, J., Mutoh, T., Nakamura, Y., Saito, K., Sakamoto, R., Seki, T., Shoji, M., Takami, S., Watanabe, T., Yamamoto, T., Komori, A., and Motojima, O.

Published
2008
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27. Improvement in multipass Thomson scattering system comprising laser amplification system developed in GAMMA 10/PDX

Author

Yoshikawa, M., primary, Mouri, T., additional, Nakanishi, H., additional, Kohagura, J., additional, Shima, Y., additional, Sakamoto, M., additional, Nakashima, Y., additional, Ezumi, N., additional, Minami, R., additional, Yamada, I., additional, Yasuhara, R., additional, Funaba, H., additional, Minami, T., additional, and Kenmochi, N., additional

Published
2021
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29. First electron temperature and density measurements using the multi-pass Thomson scattering system with the laser amplification system in GAMMA 10/PDX

Author

Yoshikawa, M., primary, Mouri, T., additional, Nakanishi, H., additional, Kohagura, J., additional, Shima, Y., additional, Sakamoto, M., additional, Nakashima, Y., additional, Ezumi, N., additional, Minami, R., additional, Yamada, I., additional, Yasuhara, R., additional, Funaba, H., additional, Minami, T., additional, and Kenmochi, N., additional

Published
2020
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30. Local island divertor experiments on LHD

Author

Morisaki, T., Masuzaki, S., Komori, A., Ohyabu, N., Kobayashi, M., Feng, Y., Sardei, F., Narihara, K., Tanaka, K., Ida, K., Peterson, B.J., Yoshinuma, M., Ashikawa, N., Emoto, M., Funaba, H., Goto, M., Ikeda, K., Inagaki, S., Kaneko, O., Kawahata, K., Kubo, S., Miyazawa, J., Morita, S., Nagaoka, K., Nagayama, Y., Nakanishi, H., Ohkubo, K., Oka, Y., Osakabe, M., Shimozuma, T., Shoji, M., Takeiri, Y., Sakakibara, S., Sakamoto, R., Sato, K., Toi, K., Tsumori, K., Watababe, K.Y., Yamada, H., Yamada, I., Yoshimura, Y., and Motojima, O.

Published
2005
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33. 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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34. First electron temperature and density measurements of D-module plasma in GAMMA 10/PDX using Thomson scattering and microwave interferometer systems

Author

Yoshikawa, M., primary, Kohagura, J., additional, Shima, Y., additional, Nakanishi, H., additional, Mouri, T., additional, Suto, S., additional, Nojiri, K., additional, Terakado, A., additional, Ezumi, N., additional, Sakamoto, M., additional, Nakashima, Y., additional, Minami, R., additional, Yamada, I., additional, Yasuhara, R., additional, Funaba, H., additional, Minami, T., additional, Kenmochi, N., additional, Kuwahara, D., additional, and Meiden, H. Van der, additional

Published
2019
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36. Review of initial experimental results of the PSI studies in the large helical device

Author

Masuzaki, S, Akaishi, K, Funaba, H, Goto, M, Ida, K, Inagaki, S, Inoue, N, Kawahata, K, Komori, A, Kubota, Y, Morisaki, T, Morita, S, Nakamura, Y, Narihara, K, Nishimura, K, Noda, N, Ohyabu, N, Peterson, B.J, Sagara, A, Sakamoto, R, Sato, K, Shoji, M, Suzuki, H, Takeiri, Y, Tanaka, K, Tokuzawa, T, Watanabe, T, Tsuzuki, K, Hino, T, Matsumoto, Y, Kado, S, and Motojima, O

Published
2001
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41. LHD divertor experimental program

Author

Ohyabu, N, Komori, A, Suzuki, H, Morisaki, T, Masuzaki, S, Funaba, H, Noda, N, Nakamura, Y, Sagara, A, Inoue, N, Sakamoto, R, Inagaki, S, Morita, S, Takeiri, Y, Watanabe, T, Motojima, O, Fujiwara, M, and Iiyoshi, A

Published
1999
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42. Enhancement of Helium Exhaust by Resonant Magnetic Perturbation Fields

Author

Schmitz O., Ida K., Kobayashi M., Bader A., Brezinsek S., Evans T.E., Feng Y., Funaba H., Goto M., Hegna C.C., Mitarai O., Morisaki T., Motojima G., Narushima Y., Nicolai D., Samm U., Spizzo G., Tanaka H., Yoshinuma M., and Xu Y.

Subjects
Helium Exhaust, Physics::Plasma Physics, Resonant Magnetic Perturbation Fields
Abstract

Exhaust of helium as a fusion born plasma impurity is a critical requirement for future burning plasmas. We demonstrate in this paper that resonant magnetic perturbation (RMP) fields can be used to actively improve helium exhaust features. We present results from the TEXTOR tokamak with a pumped limiter and from the LHD heliotron with the closed helical divertor. The results show an important additional functionality of the ITER RMP ELM control coils and dedicated experiments on present day devices like DIII-D, EAST or KSTAR which obtained full ELM suppression by RMP field application are motivated. In both devices RMP fields are applied to generate a magnetic island located in the very plasma edge and this magnetic island has a noticeable impact on the helium exhaust. At the TEXTOR tokamak, the effective helium confinement time p;He is reduced by up to 43% and the actual reduction depends on the coupling of the magnetic island to the pump device. The LHD heliotron device, in contrast, features intrinsically a 3D boundary and the closed helical divertor was designed for optimal pumping in this geometry. Without RMP field applied, p;He is a factor of 4 higher for LHD compared to TEXTOR discharges in a comparable plasma density range. Ion root transport -- one out of several different impurity transport regimes at LHD--is the most likely inward transport driver causing the high p;He. When a magnetic island is seeded into the intrinsic edge stochastic layer, a decrease of p;He by up to 30% and hence values closer to the tokamak situation are established. This shows that RMP fields are a fine-tuning actuator for the exhaust of helium, which is an attractive additional functionality for the ITER ELM control coils. 3D fluid plasma edge transport and kinetic neutral gas modeling with the EMC3-EIRENE code shows for LHD that the actual helium concentration in the plasma core is dominated by wall recycling of helium. This points out that the back-fuelling of the plasma by helium emitted from the plasma and recycled at the wall elements needs to be controlled. The edge magnetic island induced is shown to be an effective actuator to retain the recycled helium in the plasma periphery where it can be pumped away.

Published
2016

43. 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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44. Flow damping due to stochastization of the magnetic field

Author

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

Subjects
Physics::Fluid Dynamics, Physical sciences, Physics::Plasma Physics, Fluids and plasma physics, food and beverages, sense organs, equipment and supplies, human activities
Abstract

The driving and damping mechanism of plasma flow is an important issue because flow shear has a significant impact on turbulence in a plasma, which determines the transport in the magnetized plasma. Here we report clear evidence of the flow damping due to stochastization of the magnetic field. Abrupt damping of the toroidal flow associated with a transition from a nested magnetic flux surface to a stochastic magnetic field is observed when the magnetic shear at the rational surface decreases to 0.5 in the large helical device. This flow damping and resulting profile flattening are much stronger than expected from the Rechester-Rosenbluth model. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. This observation suggests that the flow damping is due to the change in the non-diffusive term of momentum transport.

Published
2015

46. Experimental study of particle transport and density fluctuations in LHD

Author

Tanaka, K, Michael, C, Sanin, AL, Vyacheslavov, LN, Kawahata, K, Murakami, S, Wakasa, A, Okajima, S, Yamada, H, Shoji, M, Miyazawa, J, Morita, S, Tokuzawa, T, Akiyama, T, Goto, M, Ida, K, Yoshinuma, M, Yamada, I, Yokoyama, M, Masuzaki, S, Morisaki, T, Sakamoto, R, Funaba, H, Inagaki, S, Kobayashi, M, and Komori, A

Published
2006

47. Compatibility between high energy particle confinement and magnetohydrodynamic stability in the inward-shifted plasmas of the Large Helical Device

Author

KANEKO, O., KOMORI, A., YAMADA, H., OHYABU, N., KAWAHATA, K., NAKAMURA, Y., IDA, K., MURAKAMI, S., MUTOH, T., SAKAKIBARA, S., Masuzaki, S., Ashikawa, N., Emoto, M., Funaba, H., Goto, M., Idei, H., Ikeda, K., Inagaki, S., Inoue, N., Isobe, M., Khlopenkov, K., Kubo, S., Kumazawa, R., Minami, T., Miyazawa, J., Morisaki, T., Morita, S., Muto, S., Nagayama, Y., Nakajima, N., Nakanishi, H., Narihara, K., Nishimura, K., Noda, N., Notake, T., Kobuchi, T., Liang, Y., Ohdachi, S., Oka, Y., Osakabe, M., Ozaki, T., Peterson, B. J., Sagara, A., Saito, K., Sakamoto, R., Sasao, M., Sato, K., Sato, M., Seki, T., SHIMOZUKA, T., SHOJI, M., Suzuki, H., Takechi, M., Takeiri, Y., Tamura, N., Tanaka, K., Toi, K., Tokuzawa, T., Torii, Y., Tsumori, K., Yamada, I., Yamamoto, S., Yokoyama, M., Yoshimura, Y., Yoshinuma, M., Watanabe, K.Y., Watari, T., Xu, Y., Itoh, K., Matsuoka, K., Ohkubo, K., Ohtake, I., Satow, T., Sudo, S., Yamazaki, K., Hamada, Y., Motojima, O., Fujiwara, M., O., Kaneko, A., KOMORI, H., YAMADA, N., Ohyabu, K., Kawahata, Y., Nakamura, K., Ida, S., Murakami, T., Mutoh, S., Sakakibara, S., Masuzaki, N., Ashikawa, M., Emoto, H., Funaba, M., Goto, H., Idei, K., Ikeda, S., Inagaki, N., Inoue, M., Isobe, K., Khlopenkov, S., Kubo, R., Kumazawa, T., Minami, J., Miyazawa, T., Morisaki, S., Morita, S., Muto, Y., Nagayama, N., Nakajima, H., Nakanishi, K., Narihara, K., Nishimura, N., Noda, T., Notake, T., Kobuchi, Y., Liang, S., Ohdachi, Y., Oka, M., Osakabe, T., Ozaki, B.J., Peterson, A., Sagara, K., Saito, R., Sakamoto, M., Sasao, K., Sato, M., Sato, T., Seki, T., Shimozuma, M., Shoji, H., Suzuki, M., Takechi, Y., Takeiri, N., Tamura, K., Tanaka, K., Toi, T., Tokuzawa, Y., Torii, K., Tsumori, I., Yamada, S., Yamamoto, M., Yokoyama, Y., Yoshimura, M., Yoshinuma, K.Y., Watanabe, T., Watari, Y., Xu, K., Itoh, K., Matsuoka, K., Ohkubo, I., Ohtake, T., Satow, S., Sudo, K., Yamazaki, Y., Hamada, O., Motojima, and M., Fujiwara

Subjects
Physics, High energy particle, Cyclotron, Plasma, Condensed Matter Physics, Neutral beam injection, Magnetic field, law.invention, Large Helical Device, law, Physics::Plasma Physics, Magnetohydrodynamic drive, Magnetohydrodynamics, Atomic physics
Abstract

The experimentally optimized magnetic field configuration of the Large Helical Device [A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999)], where the magnetic axis is shifted inward by 15 cm from the early theoretical prediction, reveals 50% better global energy confinement than the prediction of the scaling law. This configuration has been investigated further from the viewpoints of high energy particle confinement and magnetohydrodynamic (MHD) stability. The confinement of high energy ions is improved as expected. The minority heating of ion cyclotron range of frequency was successful and the heating efficiency was improved by the inward shift. The confinement of passing particles by neutral beam injection was also improved under low magnetic field strength, and there could be obtained an almost steady high beta discharge up to 3% in volume average. This was a surprising result because the observed pressure gradient exceeded the Mercier unstable limit. The observed MHD activities became as high as beta but they did not grow enough to deteriorate the confinement of high energy ions or the performance of the bulk plasma, which was still 50% better than the scaling. According to these favorable results, better performance would be expected by increasing the heating power because the neoclassical transport can also be improved there.

Published
2002

48. Analysis method for Thomson scattering diagnostics in GAMMA 10/PDX

Author

Ohta, K., primary, Yoshikawa, M., additional, Yasuhara, R., additional, Chikatsu, M., additional, Shima, Y., additional, Kohagura, J., additional, Sakamoto, M., additional, Nakasima, Y., additional, Imai, T., additional, Ichimura, M., additional, Yamada, I., additional, Funaba, H., additional, and Minami, T., additional

Published
2016
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50. Validations of calibration-free measurements of electron temperature using double-pass Thomson scattering diagnostics from theoretical and experimental aspects

Author

Tojo, H., primary, Yamada, I., additional, Yasuhara, R., additional, Ejiri, A., additional, Hiratsuka, J., additional, Togashi, H., additional, Yatsuka, E., additional, Hatae, T., additional, Funaba, H., additional, Hayashi, H., additional, Takase, Y., additional, and Itami, K., additional

Published
2016
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