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

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.