3D analysis of impurity transport and radiation for ITER limiter start-up configurations

Previous three-dimensional modelling of the ITER SOL plasma transport during the current ramp-up limiter phase with the EMC3-EIRENE code [M. Kobayashi et al., Nucl. Fus. 47 (2007) 61] has been extended to include the limiter-released Beryllium (Be) production, transport and radiation. The 3D density distributions of the single Be charge states and related line radiation have been simulated for two plasma densities and three plasma configurations during the ramp-up phase [G. Federici et al., J. Nucl. Mater. 363–365 (2007) 346]. The transport coefficients were also varied to check the sensitivity of the radiation to the transport. As expected, for all three configurations the radiated fraction of the SOL input power, Prad/PSOL, increases with the density at the last closed flux surface (LCFS). Preliminary results indicate largest Prad/PSOL for the 4.5 MA configuration, high density, high diffusivity case, Prad/PSOL ≈ 19%, Be concentration ≈ 16% and Zeff ≈ 2.5 at the LCFS. These absolute numbers scale linearly with the assumed sputtering coefficients, but are rather insensitive to the initial energy of the sputtered Be atoms.