Transport and MHD studies at high T-e in FTU tokamak

Magnetohydrodynamic (MHD) activity and energy transport at rational-q surfa ces is analysed on the basis of experimental results on current density pro file control obtained with localized electron cyclotron resonance heating ( ECRH) on FTU tokamak. The MHD response, in particular 2/1 and 1/1 modes, to ECRH is in agreement with expectations from a theoretical model including resistive wall braking and toroidal mode coupling. It is also shown that th e magnetic shear at r(q=1) could control m = 1 mode saturation and magnetic reconnection. Heating results with ECRH at steady state indicate that tran sport enhancement is the dominant effect on confinement at the q = 2 surfac e, and suggest that conduction and convection inside the asymmetric m = 1 i sland should both be taken into account for a proper description of the the rmal response to localized ECRH.