Experimental and numerical investigations of the beryllium concentrations in the tokamak UNITOR

Laser-induced fluorescence experiments are performed in UNITOR in order to study the release and the transport of beryllium which is ablated from poloidal limiters. The concentrations of neutral and ionized beryllium atoms are measured. The experimental results are used as input data for two-dimensional transport calculations. The results show that low-lying ionization stages of beryllium remain localized in the vicinity of the limiter. The bulk contamination consists of fully stripped beryllium at a level of about 0.9% ne at the centre. This indicates that beryllium contributes at most 0.14 to Zeff. (orig.)