Radiative divertor modelling for ITER and TPX

The B2.5 code for two-dimensional multi-species fluid modelling of the tokamak edge plasma is described and is applied for a parameter study of the effect of impurity seeding in ITER and TPX. Our modelling indicates that ITER must operate at an edge density of about 6.0 x 10(19)/m(3) and the extended performance TPX must operate at an edge density of about 5.0 x 10(19)/m(3) in order to obtain a robust divertor solution based on impurity radiation from the edge plasma only at neon concentration below 0.6% or argon concentration below 0.4%. For both devices, a high-recycling divertor solution relying on impurity radiation from core and edge together appears very credible.