A study of impurity transport in the TEXTOR plasma boundary

Impurity transport in the boundary layer of tokamaks may be crucially important in determining the impurity concentration in the plasma core. Impurity atoms or molecules released from a surface enter the plasma, are rapidly ionised and heated and at the same time undergo transport along and across the magnetic field. Because of the localisation of sources and sinks the problem is inherently 3-dimensional. A number of initial experimental investigations addressing boundary layer impurity transport have been reported and a 2-D/3-D Monte Carlo code has been developed. In the present study, we have used a system of gas-puffing through a Test Limiter to introduce impurities into plasma boundary of TEXTOR and detailed spectroscopic measurements have been made to characterize the impurity behaviour. (author) 5 refs., 4 figs