Data-driven Modeling of the Toroidal Rotation and Safety Factor Profile Dynamics for AT Scenarios in DIII-D
W. Wehner, W. Shi, C. Xu, E. Schuster, D. Moreau, D. Mazon, M. L. Walker, D. A. Humphreys, Y. In
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Salt Lake City, Utah, USA, November 14-18, 2011
Abstract
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First- principle predictive models based on flux averaged transport
equations often yield complex expressions not suitable for real-time
control. As an alternative to first- principle modeling, data-driven
modeling techniques involving system identification have the potential
to obtain low-complexity, dynamic models without the need for ad hoc
assumptions. This work focuses on the evolution of the toroidal rotation
and safety factor profiles in response to magnetic, heating and
current-drive systems. Experiments are conducted during the current
flattop, in which the actuators are modulated in open-loop to obtain
data for the model identification. The plasma profiles are discretized
in the spatial coordinate by Galerkin projection. Then a linear model
is generated by the prediction error method to relate the rotation and
safety factor profiles to the actuators according to a least squares
fit.