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Title: Physics-model-based nonlinear actuator trajectory optimization and safety factor profile feedback control for advanced scenario development in DIII-D

DIII-D experimental results are reported to demonstrate the potential of physics-model-based safety factor profile control for robust and reproducible sustainment of advanced scenarios. In the absence of feedback control, variability in wall conditions and plasma impurities, as well as drifts due to external disturbances, can limit the reproducibility of discharges with simple pre-programmed scenario trajectories. The control architecture utilized is a feedforward + feedback scheme where the feedforward commands are computed off-line and the feedback commands are computed on-line. In this work, firstly a first-principles-driven (FPD), physics-based model of the q profile and normalized beta (βN) dynamics is embedded into a numerical optimization algorithm to design feedforward actuator trajectories that sheer the plasma through the tokamak operating space to reach a desired stationary target state that is characterized by the achieved q profile and βN. Good agreement between experimental results and simulations demonstrates the accuracy of the models employed for physics-model-based control design. Secondly, a feedback algorithm for q profile control is designed following a FPD approach, and the ability of the controller to achieve and maintain a target q profile evolution is tested in DIII-D high confinement (H-mode) experiments. The controller is shown to be able to effectively controlmore » the q profile when βN is relatively close to the target, indicating the need for integrated q profile and βN control to further enhance the ability to achieve robust scenario execution. Furthermore, the ability of an integrated q profile + βN feedback controller to track a desired target is demonstrated through simulation.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [3] ;  [3] ;  [3] ;  [4] ;  [3] ;  [3]
  1. Lehigh Univ., Bethlehem, PA (United States)
  2. Lehigh Univ., Bethlehem, PA (United States); Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Columbia Univ., New York, NY (United States)
Publication Date:
OSTI Identifier:
1353105
Grant/Contract Number:
FC02-04ER54698; AC05-00OR23100; FG02-04ER54761; SC0001334; SC0010661
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 9; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma control; advanced scenario control; model-based control; safety factor profile control