[en] The stabilization of tearing magnetic islands by means of localized current driven by electron cyclotron waves, requires optimizing the efficiency of the injected helical current. The problem is conventionally addressed using 0-D model of the (generalized) Rutherford equation to find the dependence in terms of the island width, wave beam width and deposition scale length, as well as phase tracking requirements. The use of a 2-D reconnection model shows that both the early time response of a tearing unstable system to ECCD and important nonlinear processes lead to irreversible modifications on the 2-D configuration, where 'phase' and 'width' of an island cease to be observable and controllable state variables. In particular the occurrence of a phase instability and of multiple axis and current sheets, may be a serious impediment for feedback control schemes

[en] Nonlinear fluid modelling predictions of qualitatively new self-organized helical states in the reversed-field pinch configuration are confirmed by experiments in the RFX-mod device. The new states are realized by using a seed edge magnetic field, which can impose its helical pitch to the whole plasma. In simulations, we show increased magnetic order and reduced transport of magnetic field lines in regimes with the twist of a non-resonant mode. We reveal the existence of Cantori, encompassing the region characterized by conserved magnetic surfaces, which act as barriers to transport of magnetic field lines. This opens a new research line for transport studies in hot magnetized plasmas and highlights a path towards reversed-field pinches with high confinement at high current. (paper)