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

Barton, Justin E.; Boyer, Mark D.; Shi, Wenyu; Wehner, W. P.; Schuster, Eugenio; Ferron, John R.; Walker, Michael L.; Humphreys, David A.; Luce, Timothy C.; Turco, Francesca; Penaflor, B. G.; Johnson, R. D.

doi:10.1088/0029-5515/55/9/093005

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

Journal Article · Thu Jul 30 00:00:00 EDT 2015 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/55/9/093005· OSTI ID:1353105

Barton, Justin E. ^[1]; Boyer, Mark D. ^[2]; Shi, Wenyu ^[1]; Wehner, W. P. ^[1]; Schuster, Eugenio ^[1]; Ferron, John R. ^[3]; Walker, Michael L. ^[3]; Humphreys, David A. ^[3]; Luce, Timothy C. ^[3]; Turco, Francesca ^[4]; Penaflor, B. G. ^[3]; Johnson, R. D. ^[3]

Lehigh Univ., Bethlehem, PA (United States)
Lehigh Univ., Bethlehem, PA (United States); Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)
General Atomics, San Diego, CA (United States)
Columbia Univ., New York, NY (United States)

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 (β_N) 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 β_N. 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 control the q profile when β_N is relatively close to the target, indicating the need for integrated q profile and β_N control to further enhance the ability to achieve robust scenario execution. Furthermore, the ability of an integrated q profile + β_N feedback controller to track a desired target is demonstrated through simulation.

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Research Organization:: General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE Advanced Research Projects Agency - Energy (ARPA-E)

Grant/Contract Number:: FC02-04ER54698; AC05-00OR23100; FG02-04ER54761; SC0001334; SC0010661

OSTI ID:: 1353105

Alternate ID(s):: OSTI ID: 1238904

Journal Information:: Nuclear Fusion, Vol. 55, Issue 9; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 19 works

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Experimental validation of a Lyapunov-based controller for the plasma safety factor and plasma pressure in the TCV tokamak Mavkov, B.; Witrant, E.; Prieur, C. Nuclear Fusion, Vol. 58, Issue 5 https://doi.org/10.1088/1741-4326/aab16a	journal	March 2018
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