| Co-Investigator(Kenkyū-buntansha) |
KUBO Shin Natiomal Institute for Fusion Science Department of Large Helical Device Project,Associated Professor, 大型ヘリカル研究部, 助教授 (80170025)
INAGAKI Shigeru Natiomal Institute for Fusion Science Department of Large Helical Device Project,,Research Associate, 大型ヘリカル研究部, 助手 (60300729)
KAWAHATA Kazuo Natiomal Institute for Fusion Science Department of Large Helical Device Project,Professor, 大型ヘリカル研究部, 教授 (60109353)
TOKUZAWA Tokihiko Natiomal Institute for Fusion Science Department of Large Helical Device Project,,Research Associate, 大型ヘリカル研究部, 助手 (90311208)
TANAKA Kenji Natiomal Institute for Fusion Science Department of Large Helical Device Project,,Research Associate, 大型ヘリカル研究部, 助手 (50260047)
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| Research Abstract |
Recently plasma heating and plasma diagnostics using the electron Bernstein wave (EBW) have been intensively investigated, since plasma is black body for EBW even if it is low density and/or low temperature. Present research is aimed to investigate possibility of the electron temperature measurement of divertor plasma. Since EBW is an electrostatic wave, it has to be converted to a electromagnetic wave in order to go out from the plasma. In the tangential direction, EBW, which is generated in the electron cyclotron resonance layer, is converted to the X-mode in the upper-hybrid resonance layer, and the X-mode is converted to the O-mode at the cut-off layer. Then the O-mode goes out from the plasma, and finally it reaches the tangential antenna. In the present research, a tangential antenna has been installed in the LHD vacuum vessel. In this year, a remote controlled device in order to connect the ECE measurement system. So, the EBW receiver and the ECE receiver can be switched between plasma shots, EBW data have been often taken without taking special machine time. The season of LHD experiment starts in September, passes new year holidays and finishes in next February, usually. In this year, EBW data have been taken for various conditions, such as ramping-up electron density, deeply penetrating pellet injection and shallow penetrating pellet injection. As the result, when the electron density gradient is large at the plasma edge, a large emission is received with tangential antenna while fundamental ECE signal is very small. The frequency spectrum depends on the electron density profile. These phenomena cannot be explained by the multi-reflection nor the refraction of ECE. So, it may be EBW emission. Since, an EBW ray tracing code for LHD is under development in Kyoto University, and a full wave code for tangential direction is being developed in Tsukuba University, further understanding is expected for the present EBW experimental result, soon.
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