First demonstration of rotational transform control by electron cyclotron current drive in large helical device

LHD Experimental Group

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

An active current drive is a promising technique for improving plasma performances by controlling rotational transform and/or magnetic shear profiles in helical devices. A current drive based on electron cyclotron resonance heating is the most appropriate scheme for this purpose in terms of locality of driven current. Optimum conditions for an efficient electron cyclotron current drive (ECCD) in Large Helical Device (LHD) are being investigated using three-dimensional ray-tracing code, which can simulate propagation and power dissipation of electron cyclotron waves with large parallel refractive index. In the present experiment, inversion of directions of driven plasma current corresponding to injected ECCD modes was demonstrated successfully, and the results could be elucidated by the Fisch-Boozer theory. In addition, clear shifts of rotational transform were observed by motional Stark effect polarimetry. Our findings verified that the ECCD can be used as an effective actuator for controlling the rotational transform and magnetic shear profile in LHD.

Original languageEnglish
Article numberS1077
JournalPlasma and Fusion Research
Volume3
DOIs
Publication statusPublished - Jan 1 2008

Fingerprint

cyclotrons
electrons
shear
plasma currents
polarimetry
Stark effect
profiles
electron cyclotron resonance
ray tracing
dissipation
actuators
refractivity
inversions
heating
propagation
shift

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

First demonstration of rotational transform control by electron cyclotron current drive in large helical device. / LHD Experimental Group.

In: Plasma and Fusion Research, Vol. 3, S1077, 01.01.2008.

Research output: Contribution to journalArticle

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abstract = "An active current drive is a promising technique for improving plasma performances by controlling rotational transform and/or magnetic shear profiles in helical devices. A current drive based on electron cyclotron resonance heating is the most appropriate scheme for this purpose in terms of locality of driven current. Optimum conditions for an efficient electron cyclotron current drive (ECCD) in Large Helical Device (LHD) are being investigated using three-dimensional ray-tracing code, which can simulate propagation and power dissipation of electron cyclotron waves with large parallel refractive index. In the present experiment, inversion of directions of driven plasma current corresponding to injected ECCD modes was demonstrated successfully, and the results could be elucidated by the Fisch-Boozer theory. In addition, clear shifts of rotational transform were observed by motional Stark effect polarimetry. Our findings verified that the ECCD can be used as an effective actuator for controlling the rotational transform and magnetic shear profile in LHD.",
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AU - Ida, Katsumi

AU - Watanabe, Kiyomasa

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AU - Kobuchi, Takashi

AU - Inagaki, Shigeru

AU - Tokuzawa, Tokihiko

AU - Yoshimura, Yasuo

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