Investigation of transport in the ignited ITER plasma by computer simulations

Abstract

Transport simulations with special versions of the one dimensional BALDUR predictive code are used to explore the energy and particle confinement, bootstrap current, ideal ballooning stability and burn control in the high density scenario of the ITER (CDA) physics phase. The code applies empirical transport coefficients for ELMy H mode plasmas and includes a scrape-off layer (SOL) model, an impurity radiation model for helium and iron, and burn control by neutral beam injection feedback. It is shown that a self-sustained thermonuclear burn with (Ti) approximately=10 keV can be achieved for the proposed 200 s and that the burn control scheme is efficient, even in the presence of sawteeth. The required energy confinement time is found to be 4.2 s, which is achievable according to the ITER H mode scaling. The radiation loss necessary for halving the divertor heat load is attained with 0.2% iron while blowing in carbon fails because of its unfavourable radiation profile. Inclusion of the SOL model yields self-consistent densities (ne(rs)=5*1019m-3) and temperatures at the separatrix. A bootstrap current of 2.7 MA is computed, which represents a small fraction of the total current and has little impact on the current profile. The resistive timescale for current redistribution is about 100 s. Local analysis of the ideal ballooning stability shows that the plasma is stable, even with the bootstrap current included. Sensitivity studies for some uncertain parameters and dependences are carried out