Abrupt excitation of energetic-particle-driven geodesic acoustic mode in the large helical device

研究成果: Chapter in Book/Report/Conference proceedingConference contribution

2 被引用数 (Scopus)

抄録

Energetic-particle-driven geodesic acoustic mode (EGAM) is being investigated in the Large Helical Device (LHD). In this article, two topics based on observation in the LHD are presented. One is the observation of the EGAM with the frequency higher than the ordinary GAM frequency. The previous theory and experiments show that the EGAM has a frequency lower than the ordinary GAM frequency. Newly extended theory and numerical simulation have clarified that the difference in the frequency comes from the difference in the velocity distribution function of energetic particles. Another topic is the abrupt excitation of a GAM during the evolution of EGAM. As the frequency of the EGAM approaches twice the conventional GAM frequency, another GAM is excited abruptly. The experimental results indicate that the abrupt excitation of the GAM is attributed to the EGAM. A theoretical model, in which kinetic nonlinearity and fluid coupling between the GAM and the EGAM are taken into account, has successfully reproduced the experimental results. The nonlinearity in the model predict the subcritical instability of the GAM, and a threshold observed in the amplitude of the GAM seems to correspond to the necessary magnitude of the seed for the subcritical instability. Recently developed numerical simulation takes into account the kinetic coupling, which is ignored in the above theoretical model, between the EGAM and the abruptly excited GAM, and indicates that the kinetic coupling can trigger the GAM. The observation and the analysis demonstrate one experimental path for investigating the trigger problem of the onset of the abrupt phenomena.

本文言語英語
ホスト出版物のタイトルFront-runners' Symposium on Plasma Physics in Honor of Professors Kimitaka Itoh and Sanae-I. Itoh
編集者Yasushi Todo, Katsumi Ida
出版社American Institute of Physics Inc.
ISBN(印刷版)9780735417090
DOI
出版ステータス出版済み - 8 1 2018
外部発表はい
イベントFront-runners� Symposium on Plasma Physics in Honor of Professors Kimitaka Itoh and Sanae-I. Itoh, 2018 - Toki, Gifu, 日本
継続期間: 1 11 2018 → …

出版物シリーズ

名前AIP Conference Proceedings
1993
ISSN(印刷版)0094-243X
ISSN(電子版)1551-7616

その他

その他Front-runners� Symposium on Plasma Physics in Honor of Professors Kimitaka Itoh and Sanae-I. Itoh, 2018
Country日本
CityToki, Gifu
Period1/11/18 → …

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

フィンガープリント 「Abrupt excitation of energetic-particle-driven geodesic acoustic mode in the large helical device」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル