2007 Fiscal Year Final Research Report Summary
Self-Orgamzation in Low-Aspect Ratio Tens Plasma and Healing of Magnetic Chaos
| Project/Area Number |
17360441
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
MASAMUNE Sadao Kyoto Institute of Technology, Graduate School of Science and Technology, Professor (00157182)
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| Co-Investigator(Kenkyū-buntansha) |
SANPEI Akio Kyoto Institute of Technology, Graduate School of Science and Technology, Assistant Professor (90379066)
HIMURA Haruhiko Kyoto Institute of Technology, Graduate School of Science and Technology, Associate Professor (30311632)
ISHIJIMA Dai Technology Research Institute of Osaka Prefecture, Infonnation & Electronics Department, Researcher (80359398)
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| Project Period (FY) |
2005 – 2007
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| Keywords | fusion plasma / magnetic confinement / reversed field ninch(RFP) / low aspect ratio / self-organization / nonlinear MHD / magnetic chaos |
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| Research Abstract |
In this research project, we have constructed an RFP machine RELAX, whose aspect ratio (A) is 2, the world's lowest value to date. During its 1st phase operation for about a year the following discharge parameters have been achieved: maximum plasma current of <80kA, minimum discharge resistance of 1 mΩ discharge duration longer than 2 ms with RFP configuration sustained for L5-2 ms. The MHD characteristics of low-ARFP plasmas can be summarizes as follows. In flat-topped discharges, we have observed two types of toroidal mode spectrum of the m=1 modes depending upon the discharge phases. In the later phase, where the magnetic fluctuation level tends to be the lowest, the edge magnetic fluctuation has a characteristic of multi-helicity (MH) state with dominant core resonant m=1/n=4,5 modes. In the early to mid phase, periodic growth and decay of a low-amplitude (but higher than in the later phase) single mode, either n=4 or n=5, has been observed. In round-topped RFP discharges, a m=1/n=
… More
4 single dominant mode tends to grow quasi-periodically with suppression of the neighboring modes, and the toroidal mode spectrum has the quasi-single helicity (QSH) characteristic with dominant mode amplitude higher than in other RFP experiments. These observations are in agreement with theoretical predictions from low-ARFP equilibrium profiles. In RELAX, the self-reversal mode operation has also become possible, which discharge is characterized by a large-scale change in magnetic field profile. The measured profiles of asymmetric components are in good agreement with those of Helical Ohmic Equilibrium (HOE), in which RFP configuration is sustained without magnetic chaos. The measured oscillation may be an indication of toroidal rotation of the HOE configuration. A new equilibrium reconstruction code, RELAXFit, has been developed. We have extended the operation regime of the MSTFit code to the lower-A regime. This work has been performed as a part of US-Japan Fusion Collaboration Program. In the RELAXFit, we have taken into account the neoclassical effect in order to estimate the bootstrap current in RELAX. Throughout this research project, we have established the basis for further experimental study of low-A RFP configuration, a new regime of toroidal plasmas. Less
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[Journal Article] Observation of Simple Helical Structure in Low-Aspect Ratio RFP Using Fast Camera2008
Author(s)
T, Onchi, N., Nishino, R., Ikezoe, A., Sanpei, H., Himura, S., Masamune
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Journal Title
Plasma Fusion Res 3
Pages: 005-1-005-2
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Quasi-periodic growth of a single helical instability in a low-aspect raio RFP2008
Author(s)
R., Ikezoe, A., Sanpei, T., Onchi, K., Oki, H., Himura, S., Masamune
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Journal Title
Plasma Fusion Res 3(in press)
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Observation of a large-scale change of magnetic field profile in a low-aspect ratio reversed field pinch2008
Author(s)
K., Oki, R., Ikezoe, T., Onchi, A., Sanpei, H., Himura, S., Masamune, R., Paccagnella
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Journal Title
J. Phys. Soc. Jpn 77,No.7(in press)
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Experimental verification of non-constant potential and density on magnetic surfaces of helical nonneutral plasmas2007
Author(s)
H., Himura, H., Wakabayashi, Y., Yamamoto, M., Isobe, S., Okamura, K., Matsuoka, A., Sanpei, S., Masamune
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Journal Title
Phys. Plasmas 14
Pages: 022507-1-022507-7
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Research plans for low-aspect ratio Reversed Field Pinch(RFP)2007
Author(s)
S., Masamune, A., Sanpei, H., Himura, R., Ikezoe, T., Onchi, M., Nagata, H., Hiramatsu, D., Ishijima
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Journal Title
Trans. Fusion Science and Technology 51(No.2T)
Pages: 197-199
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Hot Electron Plasmas Trapped in Helical Magnetic Surfaces2007
Author(s)
H., Himura, H., Wakabayashi, Y., Yamamoto, M., Isobe, S., Okamura, K., Matsuoka, A., Sanpei, S., Masamune
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Journal Title
Hyperfine Interactions 174
Pages: 83-88
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Electron current measurement of helical nonneutral plasmas for investigating plasma disruption observed in CHS experiments2007
Author(s)
H., Himura, Y., Yamamoto, A., Sanpei, S., Masamune, M., Isobe, S., Okamura, K., Matsuoka
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Journal Title
Plasma Fusion Res 2
Pages: S1089-1-S1089-4
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Probing of toroidal electron plasmas confined on helical magnetic surfaces2007
Author(s)
Y., Yamamoto, H., Himura, A., Sanpei, S., Masamune, M., Isobe, S., Okamura, K., Matsuoka
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Journal Title
Plasma Fusion Res 2
Pages: S1093-1-S1093-4
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Characterization of Initial Low-Aspect Ratio RFP Plasmas in "RELAX"2007
Author(s)
S., Masamune, A., Sanpei, R., Ikezoe, T., Onchi, K., Murata, K., Oki, H., Shimazu, T., Yamashita, H., Himura
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Journal Title
J. Phys. Soc. Jpn 76
Pages: 123501-1-123501-4
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] An optimized method of producing washers of titanium hydride for plasma gun using occluded hydrogen gas2006
Author(s)
H., Himura, Y., Saito, A., Sanpei, S., Masamune, N., Takeuchi, T., Shiono
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Journal Title
Rev. Sci. Instrum 77
Pages: 073506-1-073506-5
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Recent Results of Helical Nonneutral Plasmas on Compact Helical System2006
Author(s)
H., Himura, Y., Yamamoto, A., Sanpei, S., asamune, H., Wakabayashi, M., Isobe
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Journal Title
AIP Conf. Proc. Non-Neutral Plasma Phys 862
Pages: 51-55
Description
「研究成果報告書概要(欧文)」より
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[Presentation] Hot Electron Plasmas Trapped in Helical Magnetic Surfaces2006
Author(s)
H., Himura, H., Wakabayashi, Y., Yamamoto, M., Isobe, S., Okamura, K., Matsuoka A., Sanpei, S., Masamune
Organizer
Int. Conf. on Trapped Charged Particles and fundamental Physics 2006
Place of Presentation
Parksville, Canada
Year and Date
20060903-08
Description
「研究成果報告書概要(欧文)」より
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[Presentation] Recent Results of Helical Nonneutral Plasmas on Compact Helical System2006
Author(s)
H., Himura, Y., Yamamoto, A., Sanpei, S., Masamune, H., Wakabayashi, M., Isobe
Organizer
Workshop on Non-Netral Plasmas-2006
Place of Presentation
Aarhus, Denmark
Year and Date
20060625-29
Description
「研究成果報告書概要(欧文)」より
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