Equilibrium reconstruction improvement via Kalman-filter-based vessel current estimation at DIII-D
Y. Ou, M.L. Walker, E. Schuster and J.R. Ferron
Fusion Engineering and Design, v 82, n 5-14, Oct. 2007, p 1144-52
Abstract
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Equilibrium reconstruction codes calculate the distributions of
flux and toroidal current density over the plasma and surrounding
vacuum region that best fit the external magnetic measurements in a
least square sense, and that simultaneously satisfy the MHD
equilibrium equation (Grad-Shafranov equation).
Although these codes often use direct measurements of the
currents in the plasma and poloidal coils, they sometimes neglect the
current induced in the tokamak vessel due to the fact
that they cannot be directly measured. Kalman filtering theory is
employed in this work to optimally estimate the current in the
tokamak vessel. The real-time version of the EFIT code is modified
to accept the estimated vessel currents with the goal of improving
the equilibrium reconstruction for the DIII-D tokamak.