Plasma and Fusion Research

Volume 6, 2402073 (2011)

Regular Articles

Dependence of EC-Driven Current on the EC-Wave Beam Direction in LHD

Yasuo YOSHIMURA, Shin KUBO, Takashi SHIMOZUMA, Hiroe IGAMI, Hiromi TAKAHASHI, Masaki NISHIURA, Satoru SAKAKIBARA, Kenji TANAKA, Kazumichi NARIHARA, Takashi MUTOH, Hiroshi YAMADA, Kazunobu NAGASAKI¹⁾, Nikolai B. MARUSHCHENKO²⁾ and Yuri TURKIN²⁾

: National Institute for Fusion Science, Toki 509-5292, Japan
1): Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
2): Max-Planck-Institut for Plasmaphysik, EURATOM Association, TI Greifswald, Germany

(Received 27 December 2010 / Accepted 29 March 2011 / Published 1 July 2011)

Abstract

Electron cyclotron current drive (ECCD) experiments were conducted in the Large Helical Device to investigate the characteristics of EC-driven current and its profile and the possibility of controlling current and rotational transform profiles by ECCD. Successful ECCD helps prevent magnetohydrodynamic instabilities in plasmas. Scanning the EC-wave beam direction with a long pulse width of 8 s revealed a systematic change in the plasma current. The current's direction was reversed by a reversal of the beam direction. The direction agrees with the prediction of Fisch-Boozer theory regarding EC-wave beam injection from low-field side. The maximum driven current is 9 kA with an EC-wave power of 100 kW. The optimum beam direction that maximizes the driven current is investigated with the help of ray-tracing code. This direction depends on the magnetic field, efficiency of power absorption, and fraction of the power absorbed by trapped electrons.

Keywords

ECCD, electron cyclotron current drive, plasma current, LHD, TRAVIS

DOI: 10.1585/pfr.6.2402073

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This paper may be cited as follows:

Yasuo YOSHIMURA, Shin KUBO, Takashi SHIMOZUMA, Hiroe IGAMI, Hiromi TAKAHASHI, Masaki NISHIURA, Satoru SAKAKIBARA, Kenji TANAKA, Kazumichi NARIHARA, Takashi MUTOH, Hiroshi YAMADA, Kazunobu NAGASAKI, Nikolai B. MARUSHCHENKO and Yuri TURKIN, Plasma Fusion Res. 6, 2402073 (2011).