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22-27 October 2018
Mahatma Mandir Conference Centre
Asia/Kolkata timezone
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Study of locking mechanism of locked-mode-like instability in helical plasmas

24 Oct 2018, 08:30
4h
Mahatma Mandir Conference Centre

Mahatma Mandir Conference Centre

Gandhinagar (nearest Airport: Ahmedabad), India
Poster P3 Posters

Speaker

Dr Yuki Takemura (National Institute for Fusion Science)

Description

The frequency slowing-down mechanism of the locked-mode-like instability without a large magnetic island is investigated for the first time, based on the LHD experimental analysis. The slowing-down frequency is caused by two processes. One is the resonant surface moving to the small E × B rotation frequency region and the other is the slowing-down E × B rotation frequency around the resonant surface. Both processes are almost the same as those of the instability with a large magnetic island. The new exprerimental results presented in this synopsis suggest that the mode frequency slows down even though the precursor does not have a large magnetic island. In addition, the duration of the frequency slowing-down phase becomes longer as the external RMP amplitude becomes smaller. This is because the slowing-down rate of the E × B rotation frequency around the resonant surface after excitation of the precursor is smaller for a smaller external RMP amplitude. These results also suggest that error fields, which have the same effect as the RMP, should be reduced to obtain sufficient time for controlling the locked-mode-like instability.
Country or International Organization Japan
Paper Number EX/P3-16

Primary author

Dr Yuki Takemura (National Institute for Fusion Science)

Co-authors

Dr Hayato Tsuchiya (National Institute for Fusion Science) Dr Ichihiro Yamada (National Institute for Fusion Science) Dr Katsumi Ida (National Institute for Fusion Science) Dr Kiyomasa WATANABE (National Institute for Fusion Science) Dr Mikirou Yoshinuma (National Institute for Fusion Science) Prof. Satoru Sakakibara (National Institute for Fusion Science) Dr Tokihiko Tokuzawa (National Institute for Fusion Science) Dr Yoshiro NARUSHIMA (National Institute for Fusion Science)

Presentation Materials

Paper