Feedback control of dynamo tearing modes (TMs) in a reversed field pinch (RFP) using radial field sensors has been achieved in RFX-mod (Zanca et al 2012 Plasma Phys. Control. Fusion54 124018). In this paper a simulation, performed with the RFXLocking code (Zanca 2009 Plasma Phys. Control. Fusion51 015006), is presented with the purpose of discovering the dependence of TM feedback on the type (radial, poloidal and toroidal) and location of the sensors. An arrangement of the latter inside the stabilizing shell is considered. Moreover, the impact of different sensors of the sideband harmonics, produced by a uniform grid of active coils located outside the shell, is investigated. The simulations consider the layout of the Keda Torus eXperiment (KTX), a large device under construction in Hefei designed to operate in the RFP configuration. Therefore, this work can give important indications to the project of the feedback control system in the KTX. The most important result is that radial field sensors turn out to be equivalent to the poloidal and toroidal ones only upon the removal of the aliasing coming from the coils' sideband harmonics.
Intelligent shell feedback control in EXTRAP T2R reversed field pinch with partial coverage of the toroidal surface by a discrete active coil array