Physics-based control-oriented modeling of the current density profile evolution in NSTX-Upgrade

Journal Article · Thu May 11 00:00:00 EDT 2017 · Fusion Engineering and Design

DOI:https://doi.org/10.1016/j.fusengdes.2017.04.028· OSTI ID:1465372

Ilhan, Zeki O. ^[1]; Barton, Justin E. ^[1]; Schuster, Eugenio ^[1]; Gates, David A. ^[2]; Gerhardt, Stefan P. ^[2]; Menard, Jonathan E. ^[2]

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1. Lehigh Univ., Bethlehem, PA (United States)
2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Active control of the toroidal current density profile is among those plasma control milestones that the National Spherical Torus eXperiment-Upgrade (NSTX-U) program must achieve to realize its next-step operational goals. Motivated by the coupled, nonlinear, multivariable, distributed-parameter plasma dynamics, the first step towards control design is the development of a physics-based, control-oriented model for the current profile evolution in response to non-inductive current drives and heating systems. The evolution of the toroidal current density profile is closely related to the evolution of the poloidal magnetic flux profile, whose dynamics is modeled by a nonlinear partial differential equation (PDE) referred to as the magnetic-flux diffusion equation (MDE). The proposed control-oriented model predicts the spatial-temporal evolution of the current density profile by combining the nonlinear MDE with physics-based correlations obtained at NSTX-U for the electron density, electron temperature, and non-inductive current drives (neutral beams). The resulting first-principles-driven, control-oriented model is tailored for NSTX-U based on predictions by the time-dependent transport code TRANSP. Furthermore, main objectives and possible challenges associated with the use of the developed model for the design of both feedforward and feedback controllers are also discussed.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1465372
• Alternate ID(s): OSTI ID: 1631795
• Journal Information: Fusion Engineering and Design, Vol. 123, Issue C; ISSN 0920-3796
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Plasma engineering
Tokamak plasma control
Current profile control
Model-based control