TY - JOUR
T1 - Numerical optimization of actuator trajectories for ITER hybrid scenario profile evolution
JF - Plasma Physics and Controlled Fusion
Y1 - 2014
A1 - van Dongen, J.
A1 - Felici, F.
A1 - Hogeweij, G. M. D.
A1 - Geelen, P.
A1 - Maljaars, E.
AB - Optimal actuator trajectories for an ITER hybrid scenario ramp-up are computed using a numerical optimization method. For both L-mode and H-mode scenarios, the time trajectory of plasma current, EC heating and current drive distribution is determined that minimizes a chosen cost function, while satisfying constraints. The cost function is formulated to reflect two desired properties of the plasma q profile at the end of the ramp-up. The first objective is to maximize the ITG turbulence threshold by maximizing the volume-averaged s / q ratio. The second objective is to achieve a stationary q profile by having a flat loop voltage profile. Actuator and physics-derived constraints are included, imposing limits on plasma current, ramp rates, internal inductance and q profile. This numerical method uses the fast control-oriented plasma profile evolution code RAPTOR, which is successfully benchmarked against more complete CRONOS simulations for L-mode and H-mode mode ITER hybrid scenarios. It is shown that the optimized trajectories computed using RAPTOR also result in an improved ramp-up scenario for CRONOS simulations using the same input trajectories. Furthermore, the optimal trajectories are shown to vary depending on the precise timing of the L–H transition.
VL - 56
SN - 0741-3335
IS - 12
U1 - FP
U2 - CPP-HT
U5 - 66153de32ffd1ed712c0055e71e44bf6
ER -