Robust control of the safety factor profile and stored energy evolutions in high performance burning plasma scenarios in the ITER tokamak

Barton, Justin; Besseghir, Karim; Lister, J.B.; Schuster, Eugenio

doi:10.1109/cdc.2013.6760533

Cited by 9 publications

(4 citation statements)

References 15 publications

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“…The developed feedforward + feedback scheme has been employed to improve the reproducibility of plasma startup conditions on DIII-D by achieving a specified target q profile at the end of the current ramp-up phase [54,57]. Additionally, feedback algorithms for profile control have been developed for tracking of q profile targets in NSTX-U H-mode scenarios [58] and in TCV L-mode scenarios [54,59], simultaneous tracking of q profile and β N targets in ITER burning plasma H-mode scenarios [54,60] and simultaneous tracking of q profile and T e profile targets in TCV L-mode scenarios [54,61]. with Lagrange multiplier σ ( ) k , is given by (A.7).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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

et al. 2015

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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 preprogrammed 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, a first-principles-driven (FPD), physics-based model of the q profile and normalized beta (β N) dynamics is first embedded into a numerical optimization algorithm to design feedforward actuator trajectories that steer 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. Second, a feedback algorithm for q profile control is designed following an 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. The ability of an integrated q profile + β N feedback controller to track a desired target is demonstrated through simulation.

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Section: Conclusion and Discussionmentioning

confidence: 99%

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

et al. 2015

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“…While the poloidal magnetic flux Ψ r is a natural choice to describe the plasma state, control objectives are generally formulated in terms of the safety factor [6,43] or its inverse [14]. A change of variable is then necessary to convert Ψ r into the controlled variable.…”

Section: Appendix a Estimation Of The Safety Factor Profilementioning

confidence: 99%

Multi-experiment state-space identification of coupled magnetic and kinetic parameters in tokamak plasmas

Mavkov

Witrant

Prieur

et al. 2017

Control Engineering Practice

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International audienceThis paper describes an identification technique for control-oriented linear time-invariant models of the coupled dynamics of the electron temperature and the poloidal magnetic flux for advanced operational tokamak scenarios. The actuators consist of two neutral beam injectors, an electron cyclotron current drive and the ohmic coil that provides the loop voltage at the plasma surface. The model is identified using a combination of subspace and output-error methods for state-space multiple-input and multiple-output system identification. This identification is applied on sets of simulated data from the METIS tokamak simulator with parameters typical of the DIII-D tokamak, and the results of the identification are presented

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“…In that work the control-oriented model is obtained from experimental data using a generic two time-scales method. Simultaneous control of the q-profile and β N using first-principles-driven physicsbased model is developed for DIII-D H-mode scenarios in [11] and for ITER H-mode scenarios in [12,13]. The control models used in these works are spatially discretized.…”

Section: Introductionmentioning

confidence: 99%

Experimental validation of a Lyapunov-based controller for the plasma safety factor and plasma pressure in the TCV tokamak

Mavkov¹,

Witrant²,

Prieur³

et al. 2018

Nucl. Fusion

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In this paper model-based closed-loop algorithms are derived for distributed control of the inverse of the safety factor profile and the plasma pressure parameter β of the TCV tokamak. The simultaneous control of the two plasma quantities is performed by combining two different control methods. The control design of the plasma safety factor is based on an infinite-dimensional setting using Lyapunov analysis for partial differential equations, while the control of the plasma pressure parameter is designed using control techniques for singleinput and single-output systems. The performance and robustness of the proposed controller is analyzed in simulations using the fast plasma transport simulator RAPTOR. The control is then implemented and tested in experiments in TCV Lmode discharges using the RAPTOR model predicted estimates for the q-profile. The distributed control in TCV is performed using one co-current and one countercurrent Electron Cyclotron Heating actuation.

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Robust control of the safety factor profile and stored energy evolutions in high performance burning plasma scenarios in the ITER tokamak

Cited by 9 publications

References 15 publications

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

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

Multi-experiment state-space identification of coupled magnetic and kinetic parameters in tokamak plasmas

Experimental validation of a Lyapunov-based controller for the plasma safety factor and plasma pressure in the TCV tokamak

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