Analysis of the Da spectral line shape on the carbon limiter insertion experiments in Heliotron J H. Kawazome a, * , K. Takahashi a , S. Tsuboi a , H. Arimoto a , T. Mizuuchi b , N. Nishino c , H. Okada b , K. Nagasaki b , S. Kobayashi b , S. Yamamoto b , Y. Suzuki a , K. Ohashi a , S. Nakazawa a , M. Kaneko a , H. Shidara a , Y. Fukagawa a , S. Nishio a , M. Yamada a , H. Yamazaki a , K. Kondo a , F. Sano b a Graduate School of Energy Science, Kyoto University, Gokasho, Uji Kyoto 611-0011, Japan b Institute of Advanced Energy, Kyoto University, Gokasho, Uji Kyoto 611-0011, Japan c Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8527, Japan Abstract In order to investigate the velocity distribution function of deuterium atoms, which gives information about the recy- cling process, in the Heliotron J edge plasma region, spectral line shapes of Da emitted in front of a carbon limiter have been measured with a high-resolution spectrometer. Measured spectral profiles have an asymmetric structure and are decomposed into the broad and narrow Gaussian components. The central wavelengths of each component shift toward the blue side. The intensity distribution is similar to the footprint of the magnetic field lines on the limiter sur- face. The emission from reflected atoms affects the intensity distribution of the broad component. Ó 2004 Elsevier B.V. All rights reserved. PACS: 52.40.w; 52.40.Hf Keywords: Heliotron J; Hydrogen atoms; Limiter; Spectroscopy 1. Introduction In order to control fuelling, pumping and impurity generation in fusion plasmas, understanding the behav- ior of neutral deuterium (hydrogen) atoms in the edge and divertor region is necessary. The essential parame- ters for understanding their behavior are the velocity distribution and flow velocity. Knowledge of the velocity distribution determines the penetration depth of the neu- tral atoms and gives information about the recycling process. The velocity distribution of the deuterium atoms is composed of low and high energy components. The low energy component is due to molecular dissoci- ation and ionization. The high energy component is the contribution of the reflected atoms and the atoms produced by the charge exchange reaction. A detailed analysis of spectral profiles of Da provides information on the behavior of neutral deuterium atoms. High-reso- lution spectroscopic measurements are very powerful methods and performed in many magnetically confined devices [1–6]. In this paper, behavior of the deuterium atoms in front of a carbon limiter has been investigated 0022-3115/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jnucmat.2004.09.046 * Corresponding author. Tel.: +81 774 38 4442; fax: +81 774 32 9397. E-mail address: kawazome@center.iae.kyoto-u.ac.jp (H. Kawazome). Journal of Nuclear Materials 337–339 (2005) 490–494 www.elsevier.com/locate/jnucmat