@article{7874,
  author = {J. van Dongen and F. Felici and G. M. D. Hogeweij and P. Geelen and E. Maljaars},
  title = {Numerical optimization of actuator trajectories for ITER hybrid scenario profile evolution},
  abstract = {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.},
  year = {2014},
  journal = {Plasma Physics and Controlled Fusion},
  volume = {56},
  pages = {125008},
  isbn = {0741-3335},
  doi = {10.1088/0741-3335/56/12/125008},
  language = {eng},
}