[Table of Contents]

Plasma and Fusion Research

Volume 5, S2042 (2010)

Regular Articles

Evaluation of Fast-Ion Confinement Using a Radially Injected Neutral Beam in the LHD
Masaki OSAKABE, Sadayoshi MURAKAMI1), Takafumi ITOH, Mitsutaka ISOBE, Shinji KOBAYASHI2), Tokihiko TOKUZAWA, Kenichi NAGAOKA, Haruhisa NAKANO, Katsuyoshi TSUMORI, Katsunori IKEDA, Yasuhiko TAKEIRI, Osamu KANEKO and LHD-group
National Institute for Fusion Science,322-6 Oroshi-cho, Toki 509-5292, Japan
1)
Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501, Japan
2)
Department of Kyoto University, Uji 611-0011, Japan
(Received 18 January 2010 / Accepted 14 May 2010 / Published 10 December 2010)

Abstract

The confinement properties of perpendicular fast ions, which have kinetic energies mostly perpendicular to magnetic field lines, are investigated in the Large Helical Device (LHD) using short pulse injections of neutral beams (NB). Fast-ion lifetimes are evaluated using the fast neutral decay times after NB turn-off, where the neutrals are measured by an array of silicon-diode fast neutral analyzers. We found that the lifetime normalized by the 90-degree pitch-angle scattering time can be used as a scale of fast-ion confinement properties in magnetically confined fusion devices. The good confinement properties of the LHD's inwardly shifted configuration were demonstrated using the evaluated normalized lifetimes.

Keywords

fast-ion confinement, heliotron device, trapped particle, NB-blip, fast neutral measurement

DOI: 10.1585/pfr.5.S2042

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References

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This paper may be cited as follows:

Masaki OSAKABE, Sadayoshi MURAKAMI, Takafumi ITOH, Mitsutaka ISOBE, Shinji KOBAYASHI, Tokihiko TOKUZAWA, Kenichi NAGAOKA, Haruhisa NAKANO, Katsuyoshi TSUMORI, Katsunori IKEDA, Yasuhiko TAKEIRI, Osamu KANEKO and LHD-group, Plasma Fusion Res. 5, S2042 (2010).