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A spectroscopic analysis of the deuterium D alpha line (gamma = 6561.0 Å) emitted in the edge of Tore-Supra just in front of the equatorial neutralizer plate of the ergodic divertor is presented. This analysis, which relies on a line shape modelling, is focused on asymmetric D alpha spectra which are obtained in some diverted discharges. It will be shown that three populations of neutrals are necessary to interpret such spectra. A cold atoms population results from the dissociation of molecules desorbed from the surface, and a warm one from charge-exchange reactions with the plasma ions. The last population of neutrals is produced by normal reflection of plasma ions on the neutralizer V-shaped notches \mbox{(V-points)} and has an anisotropic velocity distribution function. The anisotropy of this velocity distribution function is due to its initial form and to its partial relaxation by neutral-ion elastic collisions. The analysis based on a line shape fitting program including a relaxation model allows one to estimate the relative contributions of the neutral populations of recycled deuterium to the D alpha emission and their Doppler temperatures. Finally, the dependence of the ion and neutral temperatures deduced from the fits and the dominant molecular dissociation channels are discussed as a function of the edge electron density and temperature.

Additional information

Authors: KOUBITI M ET AL, Physique des Interactions Ioniques et Moléculaires, CNRS/Université de Provence, Marseille (FR);ESCARGUEL A ET AL, Département de Recherches sur la Fusion Contrôlée, Association EURATOM-CEA Cadarache, Saint Paul lez Durance (FR)
Bibliographic Reference: An article published in: Plasma Physics and Controlled Fusion, 44, (February 2002) pp.261-275
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