Simulation of the current ramp-up phase of ITER discharges

Routine operation of ITER requires a robust current ramp-up phase. Within the narrow operational window of ITER the plasma has to be built up, preferably at low cost in terms of flux consumption, such that at the end of the current ramp-up the temperature (Ti, Te), density (ne) and current density (j) profiles have the right shape to run the wanted scenario (H-mode, hybrid mode, etc.). To perform a systematic modelling of this early phase of ITER discharges, a dedicated effort was set up within the ITER Scenarios Modelling working group. This group was formed last year as part of the EU Integrated Tokamak Modelling (ITM) Task Force, which has as long term aim to provide a European suite of software tools for ITER exploitation. The primary question to be resolved is: what are the most important actuators during the current rise phase (plasma shape, density, heating and current drive profile, etc.), and how can one achieve the profiles of q, Te, Ti, etc. that are needed to enter the various ITER scenarios. This paper discusses choices that have been made for the simulations (Sec.2), comparison of the transport codes in use (Sec.3) and calibration of the empirical transport model used so far (Sec.4). Then first results of the simulations are reported (Sec.5), followed by an outlook of future work (Sec.6). 2. Choices Based on results from existing experiments [1] and on ITER reference scenarios, following choices were made for the ITER current rise simulations.: