First neutral beam injection experiments on KSTAR tokamak

S H Jeong; D H Chang; T S Kim; S R In; K W Lee; J T Jin; D S Chang; B H Oh; Y S Bae; J S Kim; H T Park; K Watanabe; T Inoue; M Kashiwagi; M Dairaku; H Tobari; M Hanada

doi:10.1063/1.3660254

First neutral beam injection experiments on KSTAR tokamak

Rev Sci Instrum. 2012 Feb;83(2):02B102. doi: 10.1063/1.3660254.

Authors

S H Jeong¹, D H Chang, T S Kim, S R In, K W Lee, J T Jin, D S Chang, B H Oh, Y S Bae, J S Kim, H T Park, K Watanabe, T Inoue, M Kashiwagi, M Dairaku, H Tobari, M Hanada

Affiliation

¹ Korea Atomic Energy Research Institute (KAERI), 989-111 Daedeokdaero, Yuseong-gu, Daejeon 305-353, South Korea. shjeong2@kaeri.re.kr

PMID: 22380259
DOI: 10.1063/1.3660254

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.