Plasma and Fusion Research

Volume 3, S1008 (2008)

Regular Articles

ECCD Experiments in Heliotron J, TJ-II, CHS, and LHD
Kazunobu NAGASAKI1), Gen MOTOJIMA2), Angela C. FERNÁNDEZ3), Álvaro A. CAPPA3), Jose Maria FONTDECABA3), Yoshio YOSHIMURA4), Takashi NOTAKE4), Shin KUBO4), Takashi SHIMOZUMA4), Hiroe IGAMI4), Katsumi IDA4), Mikio YOSHINUMA4), Takashi KOBUCHI4), Heliotron J Team1,2), TJ-II Team3), CHS Team4) and LHD Team4)
1)
Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
2)
Graduate School of Energy Science, Kyoto University, Uji 611-0011, Japan
3)
Laboratorio Nacional de Fusio'n, EURATOM-CIEMAT, Madrid 28040, Spain
4)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 15 November 2007 / Accepted 5 February 2008 / Published 1 August 2008)

Abstract

Electron cyclotron current drive (ECCD) experiments were conducted in the stellarator/heliotron (S/H) devices, such as Heliotron J, TJ-II, CHS, and LHD. Experimental results show that ECCD can be controlled by the power injection angle, absorption position and magnetic field structure. The current drive efficiencies are similar, γ = neIECR/PEC = 8 - 16×1016 A/Wm2 , ζ = 32.7neIECR/PWTe = 0.03-0.05, when the magnetic field ripple ratio is 0.93 < Bmin/Bmax < 1.0. The reversal of driven current direction is observed depending on the magnetic field ripple structure, indicating that the amplitude and direction of EC current is determined by the balance between the Fisch-Boozer effect and the Ohkawa effect, and that the Ohkawa effect is stronger in S/H devices compared with tokamaks. Control of net toroidal current by using ECCD is demonstrated; a net zero current state is attained by cancelling the bootstrap current.

Keywords

electron cyclotron current drive, stellarator, heliotron, Heliotron J, TJ-II, CHS, LHD, current drive efficiency, Fisch-Boozer effect, Ohkawa effect

DOI: 10.1585/pfr.3.S1008

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This paper may be cited as follows:

Kazunobu NAGASAKI, Gen MOTOJIMA, Angela C. FERNÁNDEZ, Álvaro A. CAPPA, Jose Maria FONTDECABA, Yoshio YOSHIMURA, Takashi NOTAKE, Shin KUBO, Takashi SHIMOZUMA, Hiroe IGAMI, Katsumi IDA, Mikio YOSHINUMA, Takashi KOBUCHI, Heliotron J Team, TJ-II Team, CHS Team and LHD Team, Plasma Fusion Res. 3, S1008 (2008).