Physics-based Control-oriented Modeling of the Current Profile Evolution in NSTX-Upgrade
Z. Ilhan, J. Barton, W. Shi, E. Schuster, D. Gates, S. Gerhardt, E. Kolemen, J. Menard
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Denver, Colorado, USA, November 11-15, 2013
Abstract
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The operational goals for the NSTX-Upgrade device include non-inductive
sustainment of high-β plasmas, realization of the high performance
equilibrium scenarios with neutral beam heating, and achievement of
longer pulse durations. Active feedback control of the current profile
is proposed to enable these goals. Motivated by the coupled, nonlinear,
multivariable, distributed-parameter plasma dynamics, the first step
towards feedback 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. For this purpose,
the nonlinear magnetic-diffusion equation is coupled with empirical
models 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 the PTRANSP
predictions. Main objectives and possible challenges associated with
the use of the developed model for control design are discussed.