title: First neutral beam injection experiments on KSTAR tokamak.
abstract: The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1∕3 of its full design capability, and NB heating experiments were carried out during the 2010 KSTAR operation campaign. The ion source is composed of a JAEA bucket plasma generator and a KAERI large multi-aperture accelerator assembly, which is designed to deliver a 1.5 MW, NB power of deuterium at 95 keV. Before the beam injection experiments, discharge, and beam extraction characteristics of the ion source were investigated. The ion source has good beam optics in a broad range of beam perveance. The optimum perveance is 1.1-1.3 μP, and the minimum beam divergence angle measured by the Doppler shift spectroscopy is 0.8°. The ion species ratio is D(+):D(2)(+):D(3)(+) = 75:20:5 at beam current density of 85 mA/cm(2). The arc efficiency is more than 1.0 A∕kW. In the 2010 KSTAR campaign, a deuterium NB power of 0.7-1.5 MW was successfully injected into the KSTAR plasma with a beam energy of 70-90 keV. L-H transitions were observed within a wide range of beam powers relative to a threshold value. The edge pedestal formation in the T(i) and T(e) profiles was verified through CES and electron cyclotron emission diagnostics. In every deuterium NB injection, a burst of D-D neutrons was recorded, and increases in the ion temperature and plasma stored energy were found.
authors.affiliation: Korea Atomic Energy Research Institute (KAERI), 989-111 Daedeokdaero, Yuseong-gu, Daejeon 305-353, South Korea. shjeong2@kaeri.re.kr
authors.forename: S H
authors.initials: SH
authors.lastname: Jeong
authors.forename: D H
authors.initials: DH
authors.lastname: Chang
authors.forename: T S
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authors.lastname: Kim
authors.forename: S R
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authors.lastname: Bae
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authors.forename: H T
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authors.lastname: Park
authors.forename: K
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authors.lastname: Watanabe
authors.forename: T
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authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Kashiwagi
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authors.lastname: Dairaku
authors.forename: H
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authors.lastname: Tobari
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authors.lastname: Hanada