1990 Fiscal Year Final Research Report Summary
Frequency Shift of Submm Waues with a Super Rotating Grating
| Project/Area Number |
01880003
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| Research Category |
Grant-in-Aid for Developmental 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 |
MAEKAWA Takashi Kyoto Univ., Faculty of Science, Instructor, 理学部, 助手 (20127137)
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| Co-Investigator(Kenkyū-buntansha) |
KUDO Shin National Institute for Fusion Science, Instructor, 助手 (80170025)
TANAKA Shigetoshi Kyoto Univ., Faculty of Science, Professor, 理学部, 教授 (20025240)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Plasma Diagnostics / Rotating Grating / Submm Wave / Interferometer / Scattering Measuementr |
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| Research Abstract |
1. Frequency shift of omega_<IF>/2pi=1.45 MHz is obtained for 337 mum HCN laser beam by use of a rotating grating fabricated on the top of the rotor of a turbo-molecular pump with a high rotating speed of 43200 rpm. (Super Rotating Grating). The frequency shift is one order higher than those with usual rotating gratings. Using this as a local beam, heterodyne detection of low frequency microturbulence as well as high time resolution interferometry in plasmas becomes possible with a single FIR laser.
2. The frequency-shifted beam is slightly frequency-modulated (modulation index M_f<similar or equal>1.2) with a period equal to the rotation period of the grating. This frequency modulation does no harm to these diagnostics.
3. The power conversion efficiency of the SRG measured with a pyroelectric detector is 0.2 for a teflon window and 0.25 for a crystal quartz window. We will increase the efficiency in a future work. The present efficiency may be, however, sufficient to carry out multichannel detection with a channel number of 10 or more, since 337 mum HCN lasers generate a large power.
4. We intend to make a multi-channel interferometer of high time resolution as well as a scattering apparatus with heterodyne detection system by using the SRG and to study transport phenomena such as sawtooth oscillations and low frequency microtubulences in tokamak plasmas.
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