1992 Fiscal Year Final Research Report Summary
Studies on the Current-Density-Dependences of Transports and Heating in Low q Current-Carrying Plasmas
| Project/Area Number |
02402052
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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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 | University of Tokyo |
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Principal Investigator |
INOUE Nobuyuki University of Tokyo, Department of Nuclear Engineering, Professor, 工学部, 教授 (60023719)
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| Co-Investigator(Kenkyū-buntansha) |
TOYAMA Hiroshi University of Tokyo, Department of Physics, Associate Professor, 工学部, 助教授 (50023718)
MORIKAWA Junji University of Tokyo, Department of Nuclear Engineering, Technical Staff, 工学部, 教務職員 (70192375)
NIHEI Hitoshi University of Tokyo, Department of Nuclear Engineering, Research Associate, 工学部, 助手 (70010973)
YOSHIDA Zensho University of Tokyo, Department of Nuclear Engineering, Associate Professor, 工学部, 助教授 (80182765)
OGAWA Yuichi University of Tokyo, Department of Nuclear Engineering, Associate Professor, 工学部, 助教授 (90144170)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Plasma / Nuclear Fusion / Anomalous Heating / Anomalous Resistance / ULQ / Tokamak / Ion Viscosity |
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| Research Abstract |
When we increase the plasma current in a toroidal discharge, the plasma becomes unstable against kink modes. Simultaneously we observe an appreciableincrease in the effective resistance (dissipating impedance) of the discharge. The transition into a turbulent discharge resembles the appearance of a turbulent viscosity in a flow through a tube. To characterize a toroidal discharge, we use the surface safety factor q_a which is approximately proportional to the ratio of the toroidal and poloidal magnetic fields at the plasma surface. A smaller q_a, for example q_a<1, is obtained only when we apply an anomalously large loop voltage to sustain the discharge. An experimental scaling law of the anomalous impedance has been established. Expentimantal and theoretical analyzes of the kink-tearing turbulence have clarified the self-consistent relations among the anomalous impedance, anomalous heation, and the self-organization phenomena which are key characteristics of the high current density plasmas.
In the magnetohydrodynamic relaxation accompanying fast reconnections, magnetic fluctuations originating from kink-type instabilities yield a finite magnetic compression, and the corresponding transverse electric field is dissipated through the transit-time damping. This dissipation mechanism does not change the helicity, while it dissipates the fluctuation energy to result in direct heating of ions. This is in contrast to a slow relaxation process based on the tearing mode turbulence, where the parallel electric field is predominantly dissipated, which accompanies preferential heating of electrons and dissipation of the helicity.
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