[Table of Contents]

Plasma and Fusion Research

Volume 8, 2402115 (2013)

Regular Articles

Local and Fast Density Pump-out by ECRH in the LHD
Ryohei MAKINO1), Shin KUBO1,2), Takeshi IDO1,2), Kenji TANAKA2), Takashi SHIMOZUMA2), Yasuo YOSHIMURA2), Masaki NISHIURA2), Hiroe IGAMI2), Hiromi TAKAHASHI2), Akihiro SHIMIZU2) and Shinya OGASAWARA1)
1)
Department of Energy Engineering and Science, Nagoya University, Nagoya 404-8603, Japan
2)
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 7 December 2012 / Accepted 30 May 2013 / Published 26 September 2013)

Abstract

A decrease in the electron density is observed during high-power heating, particularly in electron cyclotron resonance heating (ECRH). One possible mechanism is the increase in the number of trapped particles, which can enhance the radial particle flux, because ECRH accelerates electrons in a direction perpendicular to the magnetic field lines. To observe the effects of the production of trapped particles, high-power (1 MW) ECRH was applied at the ripple bottom of the magnetic field strength, where trapped particles are readily produced. A rapid local outward flux of electrons was first observed near the heating position shortly after ECRH injection. The outward flux is proportional to the electron density in the density range of 0.4 × 1019 to 0.8 × 1019 m−3. The inward electron flux was subsequently enhanced in the core region.

Keywords

density pump-out, ECRH, particle, transport, modulation, LHD

DOI: 10.1585/pfr.8.2402115

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This paper may be cited as follows:

Ryohei MAKINO, Shin KUBO, Takeshi IDO, Kenji TANAKA, Takashi SHIMOZUMA, Yasuo YOSHIMURA, Masaki NISHIURA, Hiroe IGAMI, Hiromi TAKAHASHI, Akihiro SHIMIZU and Shinya OGASAWARA, Plasma Fusion Res. 8, 2402115 (2013).