Abstract. The screening effect of Ne and C in ergodic divertor plasmas is studied. Spectroscopic measurements show that the screening mechanism is not the same for the two impurities. A 2D model explains this difference by the longer penetration length of neutral Ne. 3D modelling of the plasma edge with the BBQ code confirms the brightness profile shape dependence on the edge Te. The 1D impurity transport code MIST coupled to BBQ interprets the screening effect as posssibly due to strong impurity outfluxes coming out of the ergodic region.
IAEA 2001