Kalman Filters to Reduce Noise Effects during External Kink Control*

Magnetic feedback control of the resistive wall mode in tokamaks use derivative (and proportional) gain in order to optimize stabilization\footnote{M. Okabayshi, \textit{et al.}, Phys. Plasmas, {\bf 8}, 2071 (2001).}$^,$\footnote{Y. Liu, \textit{et al.}, Nuc. Fusion, {\bf 44}, 232 (2004).} and to adjust the phase response during control of rotating kinks.\footnote{A.Klein, \textit{et al.}, Phys. Plasmas, {\bf 12}, 040703 (2005).} Derivative gain amplifies noise and can lead to large and undesirable fluctuations in the feedback control current. In this poster, a recipe is presented for the implementation of a Kalman filter that tracks kink mode dynamics as recently described.\footnote{M. E. Mauel, \textit{et al.}, Nuc. Fusion, {\bf 45}, 285 (2005).} Numerical simulations demonstrate the use of the control algorithm for various configurations of magnetic field sensors and control coils used in the HBT-EP device. By properly tracking both the wall and plasma modes, feedback control is maintained up to the ideal wall limit in rotating discharges in the presence of measurement noise.