1994 Fiscal Year Final Research Report Summary
MECHANISM FOR GENERATION AND RELAXATION OF DISRUPTIONS BASED ON NAMOLAOUS TRANSPORT
| Project/Area Number |
04808002
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
プラズマ理工学
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| Research Institution | National Institute for Fusion Science |
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Principal Investigator |
ITOH Kimitaka National Institute for Fusion Sicence, Associate Professor, 大型ヘリカル研究部, 助教授 (50176327)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUYAMA Atsusi Faculty of Engineering, Okayama University, Associate Professor, 工学部, 助教授
ITOH Sanae-i Research Institute for Applied Mechanics, Kyusyu University, Professor, 応用力学研究所, 教授 (70127611)
TOI Kazuo National Institute for Fusion Sicence, Professor, 大型ヘリカル研究部, 教授 (20093057)
SANUKI Heiji National Institute for Fusion Sicence, Associate Professor, 大型ヘリカル研究部, 助教授
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| Project Period (FY) |
1992 – 1994
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| Keywords | Disruptive Instability / Anomalous Transport / Toroidal Plasmas / Magnetic Stochasticity / Bifurcation / Turbulence / Viscosity |
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| Research Abstract |
This research aims to provide a basic understanding for the various disruptive phenomena in toroidal plasmas. We propose a new mechanism of the nonlinear link between the anomalous transport and the plasma instabilities. It is found that the electron viscosity, which is enhanced much if the stachasticity condition is satisfied, can cause the increment in the instability glowth rate. As a result of this coupling, an explosive burst of the plasma deformation occurs, in the case that the perturbation amplitude exceeds a threshold condition for the magnetic stochasticity. If the deformation becomes so large that the ion viscosity is enhanced, then the mode growth is prohibited. These mechanisms explain an abrupt occurence of the disruption, rapid growth which seems to be independent of the resistivity, and the sudden termination of the destruction.
This methodology is extended to the microscopic fluctuations in the plasma. It is found that the plasma turbulence can causes the growth of fluctuations : The stationary state is realized by the ballance between the nonlinear destabilization (via electreon viscosity) and the nonlinear stabilization (through ion viscosity and thermal diffusivity). This theoretical framwork gives a qualitative advancement in the transport theory in comparison with the conventional quasi-linear picture of turbulence. The transport coefficient, which is given by this'Self-sustained Thrbulence'theory, seems to explain various features in the L-mode and improved confinement modes in toroidal plasmas.
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