| Project/Area Number |
63580015
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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 | Nihon University |
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Principal Investigator |
TAKAHASHI Tsutomu Nihon University, College of Science and Technology, Assistant, 理工学部, 助手 (50179496)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMAMURA Shin Nihon University, College Science and Technology, Assistant, 理工学部, 助手 (00059627)
NOGI Yasuyuki Nihon University, College Science and Technology, Assistant Professor, 理工学部, 助教授 (90059569)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1988: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Field Reversed Configuration / Toroidal Field / Axial Alternating Current / Amplification of Bias Flux / Stabilization of Rotational Instability / Fluctuating Magnetic Field / Dipole Current / Quadrupole Current / 逆転磁場配位プラズマ / 動的安静化 / バイアス磁場の増幅 / 多重極電流 / FRC / トロイダル磁場を含むFRC / 高周波電流 / n=2回転不安定性の抑制 / Boプローブ / フォトダイオード / FRCプラズマの中心位置 / 逆転磁場配位 / プラズマの長さ計測 |
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| Research Abstract |
The application of an axial current was proposed to form a field reversed configuration (FRC) plasma with a toroidal magnetic field. Effects of the axial current and threshold values of a successful FRC formation and confinement were investigated by NUCTE-3. Various frequencies (<=4.7x10^5rad/s) and amplitudes(<=6OkA) of axial currents were examined. In the formation phase, two effects were clarified ;(1) heating of the embedded plasma in the bias field (2) amplification of bias flux. In the confinement phase, the effect of stabilization of rotational instability were clarified. Though the kink instability was excited by a large axial current in both phases, it was confirmed that the instability can be avoided by using alternating current. Threshold value of the formation phase seemed to have relation with the poloidal flux limitation of a FRC formation and disturbances of preheating plasma and bias field. The stabilizing current value is almost the same as the theoretical value. But the frequency was not so high to suppress the kink mode.
A FRC plasma is usually considered as an elongated compact toroid that contains no toroidal field. But an azumuthal fluctuating magnetic field was observed by magnetic probes located on the surface of the discharge tube. The Fourier analysis of the signals showed that the n=1 mode was kept at a small level throughout the discharge but the n=2 mode grew with onset of the rotational in- stability. Current distributions should be a dipole axial current for n=1 mode and a quadrupole axial current for n=2 mode, both of which are symmetrical to the axial mideplane of FRC plasma. The mechanism of the quadruple current generation was explained from the both effects of charge separation by centrifugal force and end shortening of the charge. The dipole current seemed to generate due to a plasma motion in the confining field.
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