Current Ramp-Up in Tokamaks: From Present Experiments to ITER Scenarios

In order to prepare adequate current ramp-up and ramp-down scenarios for ITER, present experiments from several tokamaks have been analyzed by means of integrated modelling with the aim of determining relevant heat transport models for these operation phases. The results have implications on PF systems, H&CD methods for current profile shaping, and expected flux consumption in ITER. The main issue is the choice of the heat transport model. Various heat transport models have been tested by means of integrated modelling against experimental data from ASDEX Upgrade, JET and Tore Supra, including both Ohmic plasmas and discharges with additional heating/current drive (NBI, LHCD, ICRH). Validation criteria are the 0D-parameters the plasma internal inductance (li) and loop voltage (Vloop), and the 1D-parameters Te and q. Only energy transport and current diffusion are modelled; density and Zeff are taken from experiment. Only L mode plasmas are considered. In the first part of this paper the main results of these studies are presented. In the second part of the paper projections to ITER current ramp-up scenarios are shown, focusing on the baseline inductive scenario (main heating plateau current of Ip = 15MA).
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