| Project/Area Number |
02452270
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 Tsukuba |
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Principal Investigator |
INUTAKE Masaaki Univ. of Tsukuba, Institute of Applied Phys. Associate Professor, 物理工学系, 助教授 (90023738)
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| Co-Investigator(Kenkyū-buntansha) |
HOJO Hitoshi Univ. of Tsukuba, Institute of Phys. Associate Professor, 物理学系, 助教授 (30116660)
ICHIMURA Makoto Univ. of Tsukuba, Institute of Applied Phys. Assistant Professor, 物理工学系, 講師 (10151482)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 1991: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1990: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Alfven Wave / Mode Conversion / Tandem Mirror / Flute Instability / Alfven-Ion-Cyclotron Instability / Temperature Anisotropy / Radio-Frequency Heating / Plasma Physics / プラズマ理工学 / 不均一磁場 / 4重極磁場 / 非等方温度 / 微視的不安定 |
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| Research Abstract |
The quadrupole anchor cells are located between an axisymmetric central cell and axisymmetric plug /barrier cells in the GAMMA10 tandem mirror. There are recircularizing-transition regions on both sides of the anchor cell, where The magnetic flux tube has an elliptical cross section. ICRF antennas, of which azimuthal mode m can be controlled, are installed near both ends of the central cell.
It is found from wave-field measurements that a right-circularly polarized, m=+l fast Alfven wave excited in the central cell is efficiently mode converted to a left-circularly-polarized, m=-l slow Alfven wave in the anchor cell. As a physical mechanism is proposed a model that the mode conversion is brought about by a resonant mode coupling caused by the elliptical (m=<plus-minus>/-2) modulation of the flux tube in The quadruple transition region. Coupled-Alfven-wave equations are theoretically formulated, and are analytically solved under The assumption of a weakly-modulated, periodic quadruple fi
… More
eld. Theoretical results validate the above conversion model and tell that fast and slow Alfven waves do not couple with each other without the quadruple component and propagate independently. Resonant heating of the anchor ions by the mode-converted slow wave is directly confirmed with diamagnetic loops. It is found that the anchor ions are heated by the fast wave, not by the slow wave excited in the central cell and thus the conversion efficiency should be very high. Moreover, a stability boundary for the flute interchange mode has been identified by varying the anchor beta value, clearly demonstrating the validity of the averaged minimum-B stabilization of a flute mode in a tandem mirro
A microscopic instability, Alfven-ion-cyclotron (AIC) mode, expected in a high beta plasma with pressure anisotropy, has been identified in the ICRF-heaLed central-cell plasmas. Observed magnetic field fluctuations strongly depend on the temperature anisotropy and the beta value. Relaxation of the pressure anisotropy due to the AIC mode fluctuations and the concurrent increase of high energy ion loss into the mirror loss cone have been observed. Less
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