Poloidal Flux Profile Reconstruction From Pointwise Measurements via Extended Kalman Filtering in the DIII-D Tokamak
H. Wang, J.E. Barton and E. Schuster
IEEE Multi-conference on Systems and Control
Sydney, Australia, September 21-23, 2015
Abstract
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The accuracy of the internal states of a tokamak, which usually cannot
be measured directly, is of crucial importance for feedback control of
the plasma dynamics. A first-principles-driven plasma response model
could provide an estimation of the internal states given the boundary
conditions on the magnetic axis and at plasma boundary. However, the
estimation would highly depend on initial conditions, which may not
always be known, disturbances, and non-modeled dynamics. In this work,
a closed-loop state observer for the poloidal magnetic flux is proposed
based on a very limited set of real-time measurements by following an
Extended Kalman Filtering (EKF) approach. Comparisons between estimated
and measured magnetic flux profiles are carried out for several
discharges in the DIII-D tokamak. The experimental results illustrate
the capability of the proposed observer in dealing with incorrect
initial conditions and measurement noise.