(IT/P1-11) A Method for Error Field Detection in ITER

V.D. Pustovitov1)
1) Russian Research Centre ``Kurchatov Institute”, Moscow, Russian Federation

Abstract.  The problem of the error field detection in tokamaks is discussed from the viewpoint of possible application in ITER. The analyzed algorithms rely on measuring the plasma dynamic response to the finite-amplitude external magnetic perturbations, both the intrinsic error fields and pre-programmed probing pulses. In ITER such pulses can be produced by the coils designed for the static error field correction and for stabilization of the resistive wall modes, the technique used now in several tokamaks, including DIII-D and JET. Here the analysis is based on the theory predictions for the resonant field amplification (RFA). To achieve the desired level of the error field correction in ITER, the magnetic diagnostics must be sensitive to signals of several Gauss. Therefore the measurements for error field detection should be performed near the plasma stability boundary, where the RFA effect is stronger. While the proximity to the marginal stability is important, the absolute values of plasma parameters are not. This advantage can be used by lowering the plasma stability threshold in diagnostic experiments and operating in a regime much below the nominal level. The discussed method of the error field detection is an extension of the ‘active MHD spectroscopy’ recently successfully employed in the DIII-D tokamak and the EXTRAP T2R reversed-field pinch. The estimates for ITER are presented. The method can be tested in dedicated experiments in existing tokamaks.

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