Spectral profile analysis of the Dα line in the divertor region of Tore-Supra

The deuterium Balmer line Dα in Tore-Supra plasmas has been studied near a midplane neutraliser plate (NP) of the ergodic divertor. Line profiles are analysed with a synthetic profile method taking into account Zeeman and Doppler effects. This analysis shows that two deuterium populations with specific behaviours have to be considered: the first one (cold atoms) is composed of atomic deuterium coming from D2 desorbed from the NP, while the second one (warm atoms) is composed of charge exchange (CX) and reflected D. The Doppler temperature of cold atoms increases with the edge electron density, nedgee (1.4 eV<TDc<2.5 eV). Possible causes for this behaviour are analysed; in particular, the possible heating of cold atoms by D+ ions is evaluated. On the other hand, the Doppler temperature of warm atoms is not influenced by edge parameter variations (TwD∼22 eV). The densities of reflected and CX deuterium atoms are deduced from the experimental warm component brightness, coupled to a collisional radiative model and to the TRIM code; their values are in satisfactory agreement with the results of the code EDCOLL.