Influence of Drifts and Currents on the Main Operating Parameters of the Tokamak T-15MD Divertor

The work presents the results of the first calculations of the T-15MD tokamak near-wall plasma in the SOLPS-ITER code taking into account the effects of drifts and currents. The modes with the power passing through the separatrix P_SOL = 6 MW and different H gas puff intensities, corresponding to the average electron density on the separatrix, n_esep = (2–4.5) × 10¹⁹ m^–3, are considered. The same as in other tokamaks of similar size, E × B drift leads to the flow of hydrogen from the outer divertor to the inner one, which changes the load distribution between the divertor targets. Drifts also affect the flow of the carbon impurity. As a rule, when describing the dependence on the H gas puff, either n_esep or the total amount of hydrogen in the scrape off layer (SOL), N_tot, is used as a parameter characterizing the discharge. In this case, these quantities are considered as equivalent plasma characteristics in the SOL. It is shown that, from the point of view of estimating the influence of drifts, these quantities are not equivalent: the dependence of some divertor parameters on n_esep does not change with the inclusion of drifts, but the dependence on N_tot can change. It is also seen that drifts lead to a more pronounced maximum in the dependence of the saturation current on the electron density, I_sat(n_esep). This is explained by changes in the emission of the carbon impurity and the power of the recombination source of hydrogen in the divertor.