1991 Fiscal Year Final Research Report Summary
Control of Sawteeth by ECH and LHCD in the WT-3 Tokamak
| Project/Area Number |
02452273
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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. Science Professor, 理学部, 教授 (20025240)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Masahiko Osaka Institute of Technology Associate Professor, 助教授 (50172440)
IIDA Motomi Kyoto Institute of Technology Assistant, 工芸学部, 助手 (80211712)
HANADA Kazuaki Kyoto Univ. Science Sub-assistant, 理学部, 教務職員 (30222219)
MAEKAWA Takashi Kyoto Univ. Science Assistant, 理学部, 助手 (20127137)
TERUMICHI Yasushi Kyoto Univ. Science Associate Professor, 理学部, 助教授 (50025384)
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| Project Period (FY) |
1990 – 1991
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| Keywords | MHD Instability in a tokamak / Stability of sawteeth / Stabilization of MHD Instability by ECH / Stabilization of MHD Instability by LHCD / Collapse of Sawtooth / Computer Tomography / Electron Cyclotron heating / Lower hybrid current Drive |
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| Research Abstract |
1. Control of sawtooth oscillation (STO) by ECH --- (1) STO appeared in the OH plasma can be stabilized by localized ECH.
(2) The stabilization of STO is required to apply the ECH power sufficient to stabilize STO and focused by an elliptic reflector at q=l surface. (3) The threshold of the ECH power required to stabilize STO is much smaller when it is applied on the HFS as compared to the LFS. (4) This threshold power decrease with the increasing of gL and at last in qL*4.5 STO can bEf stabilized by the application of ECH at q=l surface on both HFS and LFS, where gL refers to the safety factor at the limiter. (4) STO can be stabilized by the application of ECH in high density discharge which high energy tail electrons cannot found out even during the ECh pulse. (5) The excitation of STO can be obtained by the ECH in high gL discharge which STO does not appear.
2. Control of STO by LHCD --- (1) STO can be stabilized by LHCD. (2) Then, the m=l MHD oscillation excites, but when the sufficient LH power is applied both STO and the m=l oscillation can be stabilize. (3) The ratio of the driven current by LHCD for the plasma current decreases with the increasing of gL. (4) This ratio increases with ne.
3. Analysis of sawtooth crash --- (1) The some sawteeth crashes are investigated by the time evolution of 2-dimentional soft X-ray emissivity profiles reconstructed by the technique of computer tomography. (2) Sawtooth crash appeared in ECH plasma differs from that in OH plasma.
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