1989 Fiscal Year Final Research Report Summary
Current Profile by Sub-mm Wave Polarimeter and Study of MHD Instabilities
| Project/Area Number |
63460221
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
TANAKA Shigetoshi Kyoto Univ., Phys. Dept., Professor, 理学部, 教授 (20025240)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Hitoshi Kyoto Univ., Phys. Dept., Researcher, 理学部, 教務職員 (90183863)
MAEKAWA Takashi Kyoto Univ., Phys. Dept., Researcher, 理学部, 助手 (20127137)
TERUMICHI Yasushi Kyoto Univ., Phys. Dept., As. Professor, 理学部, 助教授 (50025384)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Sub-mm Wave Polarimeter / Current Profile / MHD Instabilities / Sawtooth Oscillation |
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| Research Abstract |
A Sub-mm wave polarimeter using a HCN laser (lambda=337 mum) was produced, and the current profile of a Chemically heated (OH) plasma in WT-3 tokamak ( Ip=150 kA, N_e=5.3x10^<13> cm^<-3>, a=20 cm) was measured. The profile was consistent with the inversion radius of sawteeth oscillations (STO) determined by using CT imaging technique on soft X-ray emission in plasmas. These results suggest that overall current profile in OH plasmas depend on the value of the safety factor q_a.
STO in low density OH plasmas (n_e 0.5-1.0 x 10^<13> cm^<-3>)was suppressed completely by application of LHCD and/or ECH at the second harmonic resonance. The inversion radius of STO surface was nearly constant during application of the RF power up to the complete suppression of STO, suggesting that overall current profile was the same both in OH and RF heating plasmas. The suppression of STO therefore, seemed to be due to (1) the fast electrons and/or (2) modification of local current profile produced near the q=l surface by RF power.
Detection of the possible modification of local current profile near the q=l surface was beyond the ability of the present polarimeter. In order to overcome this difficulty, it is essential to upgrade the polarimeter in two points that (1) a long wave length probe beam (lambda=l mm may be optimum) and multi-channel measurement using an array detector.
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