Title | Numerical optimization of actuator trajectories for ITER hybrid scenario profile evolution |
Publication Type | Journal Article |
Year of Publication | 2014 |
Authors | J. van Dongen, F. Felici, G.MD Hogeweij, P. Geelen, E. Maljaars |
Journal | Plasma Physics and Controlled Fusion |
Volume | 56 |
Issue | 12 |
Pagination | 125008 |
ISBN Number | 0741-3335 |
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. |
DOI | 10.1088/0741-3335/56/12/125008 |
Division | FP |
Department | CPP-HT |
PID | 66153de32ffd1ed712c0055e71e44bf6 |
Alternate Title | Plasma Phys. Control. Fusion |
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