Statistical Analysis of the Convective Intermittent Transport at the Edge Region of QUEST

カテゴリ: 論文誌(論文単位)

グループ名: 【A】基礎・材料・共通部門

発行日: 2012/07/01

タイトル(英語): Statistical Analysis of the Convective Intermittent Transport at the Edge Region of QUEST

著者名: Santanu Banerjee (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Hideki Zushi (RIAM, Kyushu University), Nobuhiro Nishino (Mechanical System Engineering, Hiroshima University), Kazuaki Hanada (RIAM, Kyushu University), Sanj

著者名(英語): Santanu Banerjee (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Hideki Zushi (RIAM, Kyushu University), Nobuhiro Nishino (Mechanical System Engineering, Hiroshima University), Kazuaki Hanada (RIAM, Kyushu University), Sanjeev Kumar Sharma (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Tsubasa Inoue (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Haiqing Liu (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Masaki Ishiguro (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Tomofumi Ryokai (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Saya Tashima (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University), Kazuo Nakamura (RIAM, Kyushu University), Hiroshi Idei (RIAM, Kyushu University), Makoto Hasegawa (RIAM, Kyushu University), Akihide Fujisawa (RIAM, Kyushu University), Keisuke

キーワード: fast imaging，blobs，plasma current，singular value decomposition (SVD)

要約(英語): Ambient fluctuations and the generation of coherent convective structures are investigated as a function of vertical to toroidal magnetic field ratio (Bz/Bt) in the spherical tokamak QUEST [K. Hanada et al., Plasma Fusion Research 5, S1007]. Fluctuation signals are obtained at a high spatial and temporal resolution using the fast visible camera. The coherent structures (blobs) were seen to be apparent only beyond a critical Bz/Bt ratio (∼ 10-2). This clearly indicates a shift from the drift to the interchange mode with the increase in vertical magnetic field. The blobs are propagated radially at a high speed ∼ 103 m/s which is ∼ 1/10th of the ion acoustic speed in QUEST. Lifetime of the blobs is about 700 μs. Second part of the study comprises of the investigation of the finer structures in the current ramp-up phase which is characterized by lower levels of fluctuations. Singular value decomposition (SVD) and principal component analysis (PCA) techniques are applied on the fast camera images to reveal the structures which are otherwise embedded in the overall intensity image. Electron banana orbits were seen to form from the slab annular plasma and grow wider to eventually shape the plasma current front.

本誌: 電気学会論文誌A（基礎・材料・共通部門誌） Vol.132 No.7 （2012） 特集：The 16th International Workshop on Spherical Tori 2011

本誌掲載ページ: 545-554 p

原稿種別: 論文／英語

電子版へのリンク: https://www.jstage.jst.go.jp/article/ieejfms/132/7/132_545/_article/-char/ja/