[Table of Contents]

Plasma and Fusion Research

Volume 2, S1059 (2007)

Regular Articles


Study of Edge Plasma Characteristics at H-mode Transition in Heliotron J
S. WATANABE, K. NAGASAKI1), T. MIZUUCHI1), S. KOBAYASHI1), H. OKADA1), K. KONDO, S. YAMAMOTO2), Y. TORII3), M. KANEKO4), H. ARIMOTO, G. MOTOJIMA, Z. FENG5), M. NOSAKU, T. TOMOKIYO, S. MATSUOKA and F. SANO1)
Graduate School of Energy Science, Kyoto University, Uji 611-0011, Japan
1)
Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
2)
Graduate School of Engineering, Osaka University, Suita 565-0871, Japan
3)
High Temperature Plasma Center, The University of Tokyo, Kashiwa 277-8568, Japan
4)
National Institute for Fusion Science, Toki 509-5292, Japan
5)
Southwestern Institute of Physics, Chengdu 610041, China
(Received 5 December 2006 / Accepted 9 April 2007 / Published 20 November 2007)

Abstract

Characteristics of spontaneous transition to a high confinement mode (H-mode) have been studied in a helical-axis heliotron device, Heliotron J. The radiation profile measured with a silicon photodiode array shows that a interesting change in the profile occurs at the plasma edge region in the transition phase, forming a strong gradient near the last closed flux surface (LCFS). Relating to the transition, characteristics of bursty density and particle-flux fluctuations current in the scrape off layer (SOL) have been investigated. The probability distribution function for the fluctuations has a tail structure in the L-mode phase, while the tail is suppressed and its direction is reversed after the transition, which may be related to the suppression of edge-plasma turbulence.


Keywords

Heliotron J, H-mode transition, radiation profile, edge plasma turbulence, PDF

DOI: 10.1585/pfr.2.S1059


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This paper may be cited as follows:

S. WATANABE, K. NAGASAKI, T. MIZUUCHI, S. KOBAYASHI, H. OKADA, K. KONDO, S. YAMAMOTO, Y. TORII, M. KANEKO, H. ARIMOTO, G. MOTOJIMA, Z. FENG, M. NOSAKU, T. TOMOKIYO, S. MATSUOKA and F. SANO, Plasma Fusion Res. 2, S1059 (2007).