Cleaning of the Eddy Current Effects From Magnetic Diagnostics

The plasma configuration in tokamaks is created and controlled by magnetic fields generated by the external coils. Similarly, plasma macroscopic parameters are determined using sensors measuring magnetic field or magnetic flux. Some algorithms require separation of the plasma contribution from the contribution of poloidal field coils and currents induced in passive structures. In this paper, an efficient, real-time applicable method is introduced. The method is based on the identification of a state-space model in vacuum shots using both experimental and finite-element model data. The tests were performed for ISTTOK and RFX-mod. In Section II, a simple method for plasma position determination for ISTTOK is proposed. We show that the centroid position measurement by magnetic diagnostics is feasible using our algorithm for separation of the plasma signal. The correctness of the resulting method is proven by comparison with the results of the heavy-ion beam.