Experimental and theoretical evaluation of the HeII 6560.1 angstrom line contribution to the deuterium D alpha spectral line shape in Tore Supra Ergodic Divertor plasmas

The spectral profile of the deuterium D alpha line (a common diagnostic of recycling particles in present tokamaks), emitted in front of an equatorial neutralizer plate in Ergodic Divertor Tore Supra plasmas, shows, in the pr esence of large helium contents, some features which have been interpreted as the contribution of the near-by hydrogen-like helium Br beta line intens ity. In order to validate this interpretation, the intensities of several o ther He II lines have been measured, and their ratios compared to theoretic al values calculated from a collisional-radiative model. These data have be en used to estimate the brightness of the He II Br beta line. Although the effect of the He II Br beta line intensity on the D alpha line profile shap e is evaluated (and measured) to be non-negligible in these ad hoc plasmas (having a large helium content), it is concluded that it should be of no in fluence in usual fusion plasmas.