| Project/Area Number |
12480126
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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 |
Nuclear fusion studies
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| Research Institution | National Institute for Fusion Science |
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Principal Investigator |
MORISHITA Kazuo National Institute for Fusion Science, Large Helical Device Project, Professor, 大型ヘリカル研究部, 教授 (60109353)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAYAMA Yoshio National Institute for Fusion Science, Large Helical Device Project, Professor, 大型ヘリカル研究部, 教授 (10126138)
TANAKA Kenji National Institute for Fusion Science, Large Helical Device Project, Research Associate, 大型ヘリカル研究部, 助手 (50260047)
TOKUZAWA Tokihiko National Institute for Fusion Science, Large Helical Device Project, Research Associate, 大型ヘリカル研究部, 助手 (90311208)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥9,900,000 (Direct Cost: ¥9,900,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2000: ¥3,900,000 (Direct Cost: ¥3,900,000)
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| Keywords | plasma diagostics / reflectometry / ultrashort pulse / time-of-flight / density profile / fluctuations / helical plasma / 反射計 / カットオフ層 |
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| Research Abstract |
We have been developing the microwave reflectometer for the density profile and fluctuation measurements on the Large Helical Device (LHD). Since LHD has a complex magnetic field configuration and also has large magnetic shear, the launched, reflected microwave may have complicated behavior. To study the effect of strong magnetic shear, we apply the pulsed radar reflectometer. Because the pulsed radar reflectometry measures the delay time of the reflected pulse, it can be distinguished between X-mode and O-mode polarized waves even if unexpected pulses are returned. In this year we have developed and applied ultra-short-pulse reflectometer system newly to measure wider spatial range of LHD plasma. Experimental results are as follows:
1. We constructed four channel pulsed radar reflectometer system which each pulse width is about 1ns. When the direction of the electric field of the microwave adjusts the direction of the magnetic field at the location of the plasma edge, we can select the desired polarization of the reflected wave. It is obtained that the power of the reflected pulse from the plasma changes along the rotating angle of the microwave polarization.
2. By using O-mode operation, the temporal motion of the cutoff layer and the reconstructed density profile are almost in agreement with the FIR interferometer signal.
3. By using X-mode operation, the density fluctuation that the rotating island is conjectured is found to localize in the very low-density ergodic layer.
4. We have developed new reflectometer system using an ultra-short-pulse which temporal width is 23ps. On initial experiment, it can be measured that the cutoff layer is moved by the fuel pellet injection into the plasma.
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