ANALYSIS OF LUMINESCENCE SIGNALS OBSERVED DURING PELLET INJECTION

We report on a numerical analysis of luminescence signals observed during pellet injection into magnetically confined plasmas. Data from the ASDEX tokamak and the WENDELSTEIN W7-AS advanced stellarator are considered here in the form of a comparative study. We investigate how far the safety factor q and other plasma parameters influence the luminescence signals. Thus, we try to clarify the validity of the so-called neutral gas shielding model and an extension of it that takes into account the influence of resonant surfaces on the ablation process. It is shown that resonant values play only a minor role in the appearance of minima in the luminescence signals.