2002 Fiscal Year Final Research Report Summary
Effect of magnetic-field gradient on dissipation of high-beta plasmoid in high-temperature plasmas
| Project/Area Number |
11480115
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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 | National Institute for Fusion Science |
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Principal Investigator |
YAMADA Hiroshi National Institute for Fusion Science, Department of Large Helical Device, Associate Professor, 大型ヘリカル研究部, 助教授 (20200735)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Ryuichi National Institute for Fusion Science, Department of Large Helical Device, Research Associate, 助手 (10290917)
WATANABE Kiyomasa National Institute for Fusion Science, Department of Large Helical Device, Associate Professor, 大型ヘリカル研究部, 助教授 (00249963)
NAKAJIMA Noriyoshi National Institute for Fusion Science, Department of Large Helical Device, Associate Professor, 大型ヘリカル研究部, 助教授 (30172315)
TANAKA Kenji National Institute for Fusion Science, Department of Large Helical Device, Research Associate, 大型ヘリカル研究部, 助手 (50260047)
MIYAZAWA Junichi National Institute for Fusion Science, Department of Large Helical Device, Research Associate, 大型ヘリカル研究部, 助手 (50300728)
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| Project Period (FY) |
1999 – 2002
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| Keywords | Toroidal plasma / Fueling / Pellet / Cnrnpact Torus / Magnetic-field gradient / Drift / Ablation |
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| Research Abstract |
In the fueling scheme for a fusion reactor, the rank according to technical reliability is the order of gas puffing, super-sonic gas puffing, ordinary pellet injection (-1 km/s), high-speed pellet injection (>3 km/s) and compact torus (CT) injection. Potential for the efficient fueling into the core can be ranked in the opposite order. The objective of this research project is to improve efficiency of ordinary pellet injection and to promote understanding of physical process in CT injection, which have a common basis of dissipation of high-beta plasmoid in high-temprature plasmas. In particular, an effect of the gradient of magnetic field on the dissipation process has been intensively discussed. The experiment of pellet launching from different locations has been conducted in LHD which is full of variety in magnetic configuration. The outline of experimental results does not contradict the experimental observation in tokamaks. Large and quick outward density redistribution has been ob
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served in the case with low-field-side injection. Although the initial particle deposition shows an excellent agreement with the prediction from the neutral gas shielding model considering the effect of fast ions, the outward redistribution of density occurs within several hundreds μs, which cannot be described by an ordinary particle diffusion. Injection from the local high-field side mitigates this redistribution. These observations do not contradict the physical model of an ExB drift due to the gradient of magnetic field. However, the theoretical model which can deal with the toroidal averaging process during rapid expansion of the plasmoid along the magnetic field line is requisite for quantitative description of experimental results. This issue has not been recognized in the axisymmetric tokamak configuration. The acceleration of plasmoid by fast ions has been observed, which stimulates potential of tangential pellet injection. With regard to the CT injection, the analytic model to describe the motion of CT in toroidal plasmas has been investigated. The CT injector for LHD has been designed based on this analysis. The experimental verification has not been done yet, however the free flight of CT 3.6 m long has been demonstrated. The facility is now ready towards this experimental verification. Less
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Research Products
(12 results)
