Current Density Profile Estimation via Model-based Extended Kalman Filtering in the DIII-D Tokamak
H. Wang, J.E. Barton and E. Schuster
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Savannah, GA, USA, November 16-20, 2015
Abstract
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A closed-loop observer for the estimation of the poloidal magnetic
flux profile has been proposed for tokamaks in which the profile cannot
be accurately estimated in real time via equilibrium reconstruction
methods due to the lack of internal diagnostics. The observer has been
synthesized by applying extended Kalman filtering theory and using a
discrete lumped-parameter nonlinear model based on the magnetic diffusion
equation. The observer makes use of mea- surements of the total plasma
current and the poloidal magnetic flux at both the magnetic axis and
the plasma boundary to estimate the full magnetic flux profile. DIII-D
has the capability of accurately reconstructing the poloidal magnetic
flux profile by incorporating measurements by the Motional Stark Effect
(MSE) diag- nostics in the real-time equilibrium code, which makes it
a perfect testbed for the proposed observer. Comparisons between
estimated (by observer) and reconstructed (by equilibrium code) magnetic
flux profiles are carried out for several discharges in the DIII-D
tokamak, demonstrating the potential of the proposed observer.