Study of the Plasma-Neutral Relaxation in Tore-Supra Edge Plasmas

Passive spectroscopy of the Dα line emission is used for the investigation of the Tore-Supra edge plasma in front of a neutralizer plate of the Ergodic Divertor. Two kinds of spectra are observed: symmetric and asymmetric. Symmetric spectra are fitted considering two isotropic populations of deuterium representing the main neutral production mechanisms. The fit of the asymmetric spectra, requires the addition of an anisotropic population resulting from the reflection of ions as neutrals on the V-shaped notches of the neutralizer plate and the inclusion of the relaxation of the deuterium populations through elastic collisions with the plasma ions.