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Oct 13 – 18, 2014
Hotel Park Inn Pribaltiyskaya
Europe/Moscow timezone

Edge Plasma Dynamics during L-H Transition in the JFT-2M Tokamak

Oct 17, 2014, 8:30 AM
4h
Green 8-9 (Hotel Park Inn Pribaltiyskaya)

Green 8-9

Hotel Park Inn Pribaltiyskaya

Saint Petersburg, Russian Federation
Poster Poster 7

Speaker

Mr Tatsuya Kobayashi (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University)

Description

This is the first report of the spatiotemporal dynamics of edge plasma during L-H transition, which is based on the direct measurement of radial electric field, density gradient and turbulence intensity in the JFT-2M tokamak. The observations with fine spatial- and time- resolutions provide quantitatively clear views of the L-H transition, which enable us to discuss detailed physical mechanism, as follows: (i) At the L-H transition, an abrupt increase [time scale of O(100 μs)] of strong mean radial electric field (which is localized in radius with FWHM ~ 7 mm) leads the increase of density gradient and reduction of turbulence intensity. Reynolds stress force remains too small to drive the abrupt increase of the radial electric field. (ii) Rapid inward propagation of the turbulence suppression that makes front is observed at the transition. This might be linked to the fast core-edge coupling seen in global improvement of confinement after the H-mode transition.
Country or International Organisation Japan
Paper Number EX/P7-36

Primary author

Mr Tatsuya Kobayashi (Interdisciplinary Graduate School of Engineering Sciences, Kyushu University)

Co-authors

Prof. Akihide Fujisawa (Kyushu University) Dr Katsumi Ida (National Institute for Fusion Science) Dr Katsumichi Hoshino (Japan Atomic Energy Agency) Dr Kensaku Kamiya (Japan Atomic Energy Agency) Prof. Kimitaka Itoh (NIFS) Prof. Sanae Itoh (Research Institute for Applied Mechanics, Kyushu University) Dr Shigeru Inagaki (Kyushu University) Dr TAKESHI IDO (National Institute for Fusion Science) Dr Yoshihiko Nagashima (Kyushu University) Dr Yukitoshi Miura (Japan Atomic Energy Agency)

Presentation materials