AN ADVANCED STUDY OF THE IMPURITY TRANSPORT IN ITER TOKAMAK

The 2D multifluid code EPIT [1] has been used to study the problem of impurity production and transport in the ITER tokamak scrape-off layer (SOL). Calculations have been performed for beryllium, carbon and nickel target plates under the assumption that physical sputtering is the only mechanism of the impurity production. Results show that for the beryllium and carbon plates the plate erosion is high. In the case of carbon plates, up to 45% of the power flowing to the SOL can be radiated. For beryllium plates, impurity radiation is negligible. In the case of nickel, radiation is much stronger (up to 65%) and, simultaneously, impurity production much lower, while the impurity retention in the SOL improves. A simple 1D analytical model of the SOL is proposed in order to determine the dependence of the plasma parameters at the plate on the input energy, particle fluxes and the hydrogen recycling. A comparison between model predictions and code results is presented.