Current ramps in tokamaks; From present experiments to ITER scenarios
Imbeaux, F.*; Citrin, J.*; Hobirk, J.*; Hogeweij, G. M. D.*; Kchl, F.*; Leonov, V. M.*; Miyamoto, Seiji; Nakamura, Yukiharu*; Parail, V.*; Pereverzev, G. V.*; Polevoi, A.*; Voitsekhovitch, I.*; Basiuk, V.*; Budny, R.*; Casper, T.*; Fereira, J.*; Fukuyama, Atsushi*; Garcia, J.*; Gribov, Y.*; Hayashi, Nobuhiko; Honda, Mitsuru; Hutchinson, I. H.*; Jackson, G.*; Kavin, A. A.*; Kessel, C. E.*; Khayrutdinov, R. R.*; Labate, L.*; Litaudon, X.*; Lomas, P. J.*; Lnnroth, J.*; Luce, T.*; Lukash, V. E.*; Mattei, M.*; Mikkelsen, D. R.*; Nunes, I.*; Peysson, Y.*; Politzer, P.*; Schneider, M.*; Sips, G.*; Tardini, G.*; Wolfe, S. M.*; Zhogolev, V.*; ASDEX Upgrade Team*; C-Mod Team*; DIII-D Team*; JET-EFDA Contributors*; JT-60U Team; Tore Supra Teams*; Contributors of the EU-ITM ITER Scenario Modelling Group*; ITPA "Integrated Operation Scenarios" Group*; ITPA "Transport and Confinement" Group*
In order to prepare adequate current ramp-up and ramp-down scenarios for ITER, present experiments from various tokamaks have been analysed by means of integrated modelling in view of determining relevant heat transport models for these operation phases. A set of empirical heat transport models for L-mode has been validated on a multi-machine experimental dataset for predicting the dynamics within 0.15 accuracy during current ramp-up and ramp-down phases. The most accurate heat transport models are then applied to projections to ITER current ramp-up, focusing on the baseline inductive scenario (main heating plateau current of MA). These projections include a sensitivity study to various assumptions of the simulation. While the heat transport model is at the heart of such simulations, more comprehensive simulations are required to test all operational aspects of the current ramp-up and ramp-down phases of ITER scenarios. Recent examples of such simulations, involving coupled core transport codes, free-boundary equilibrium solvers and a poloidal field (PF) systems controller are also described, focusing on ITER current ramp-down.