Study of turbulent density fluctuation observed before H-mode transition based on development of 2-dimensional beam emission spectroscopy

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K06645
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Nuclear fusion studies
• Research Institution: Kyoto University
• Principal Investigator: Kobayashi Shinji 京都大学, エネルギー理工学研究所, 助教 (70346055)
• Co-Investigator(Renkei-kenkyūsha): Kado Shin-ichiro 京都大学, エネルギー理工学研究所, 准教授 (10300732) ; Oishi Tetsutaro 核融合科学研究所, 高密度プラズマ物理研究系, 助教 (80442523) ; Ohshima Shinsuke 京都大学, エネルギー理工学研究所, 助教 (00469610)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: ビーム放射分光 / 密度揺動 / ヘリカルプラズマ / H-mode遷移 / 前駆振動

Outline of Final Research Achievements

In this research, 2-dimensional (2D) density fluctuation measurement system using beam emission spectroscopy (BES) has been prepared to obtain MHD and high-frequency turbulent fluctuations. Especially, target of this research is to clarify the oscillations obtained before H-mode transition triggered by high-intensity gas puffing in Heliotron J. The frequency-wavenumber vector has been obtained by the preparation of the 2D-BES system. By applying envelope analysis to the high-frequency density fluctuation observed before the H-mode transition, a clear correlation between the high-frequency fluctuation and the low frequency density fluctuation corresponding to the particle exhaust phenomena has been found. One candidate to explain the phenomena is non-linear coupling between the two fluctuations.

Free Research Field

プラズマ物理学、核融合