2000 Fiscal Year Final Research Report Summary
A New Aspect of the Origin of Plasma Turbulence Driven by Field-Aligned Velocity Shear
| Project/Area Number |
11480104
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
プラズマ理工学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
HATAKEYAMA Rikizo Tohoku University, Grad.School of Eng., Professor, 大学院・工学研究科, 教授 (00108474)
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| Co-Investigator(Kenkyū-buntansha) |
HIRATA Takamichi Tohoku University, Grad.School of Eng., Research Associate, 大学院・工学研究科, 助手 (80260420)
OOHARA Wataru Tohoku University, Grad.School of Eng., Research Associate, 大学院・工学研究科, 助手 (80312601)
KANEKO Toshiro Tohoku University, Grad.School of Eng., Research Associate, 大学院・工学研究科, 助手 (30312599)
SATO Noriyoshi Tohoku University, Grad.School of Eng., Professor, 大学院・工学研究科, 教授 (40005252)
IIZUKA Satoru Tohoku University, Grad.School of Eng., Associate Professor, 大学院・工学研究科, 助教授 (20151227)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Field-Aligned Velocity Shear / Low-Frequency Instability / Plasma Turbulence |
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| Research Abstract |
1) A modified plasma-synthesis method is developed in order to actively control an ion flow energy in a magnetic field, where ion and electron emitters of the same diameter are oppositely set at cylindrical machine ends and the ion emitter is concentrically segmented into three sections. The field-aligned ion flows with radially-different energies are generated in a radially-uniform plasma potential when each section of the segmented ion emitter is individually biased at a positive value above the plasma potential.
2) This ion drift difference between adjacent layers, or a radial jump of the field-aligned ion flow velocity is found to give rise to several types of low-frequency instabilities.
3) One is observed around the radial center where the density profile is almost uniform. This instability is localized around the region of the flow-velocity jump, and the fluctuation amplitude becomes large when the flow-velocity difference between the two electrodes increases. Thus, this instability is considered to be related to the Kelvin-Helmholtz instability to some extent.
4) For the larger flow-velocity gradient, another is observed in the region where the density gradient is relatively large. It is found that the frequency of this instability is the sum of the electron-diamagnetic drift frequency and the frequency which is determined by the ion flow-velocity. Thus, this instability appears to be related to the electron-drift and ion-acoustic coupled wave, which has not been argued in the conventional plasma.
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