ZERO-DIMENSIONAL RELATIONSHIPS OF TOKAMAK SCRAPE-OFF-LAYER PARAMETERS AND THE INFLUENCE OF THESE PARAMETERS ON TRANSPORT IN THE MAIN PLASMA

The authors present a model for the plasma in the region outside the limiter which is suitable for describing the limiter and divertor configurations and could be used for a self-consistent study of plasma confinement in the main zone and at the edge. Integral zero-dimensional relationships are employed to describe the processes occurring in the scrape-off layer (SOL, wall plasma) region of a tokamak. This approach makes it possible to construct a model which takes into account, at least qualitatively, the principal effects that are important for the edge zone, such as ionization of neutrals, radiation, longitudinal heat transport by conduction and convection, and transverse Bohm diffusion. This model has been analysed for the main regimes of the SOL plasma. Because of the self-consistent modelling, it has been possible to describe the characteristic features of discharges in T-10 with regard to the density limit and the improved divertor confinement regimes in JT-60.