ECRH Results during Current Ramp-up and Post-Pellet Injection in FTU Plasma

Recent ECRH experiments in FTU have provided new results in two plasma scenarios, both characterized by the absence of the sawtooth activity and by flat or reversed q profiles. The first is the current ramp-up phase where low density plasmas have been heated up to high electron temperature. When the heating is localized on the plasma axis, the high additional power density has produced the evidence of a deformation of the bulk of the local electron distribution function, which is in agreement with the results of a detailed kinetic simulation. When off-axis heating is applied, no clear evidence of non-diffusive energy transport has been found. In the second scenario, ECRH has been applied on the high density plasma produced by pellet injection, resulting in strong ion heating as shown by the increase of the neutron yield. The analysis of this scenario shows that, when the post pellet phase is MHD quiescent, an enhanced energy confinement regime can be obtained with ECRH as found previously in ohmically heated post-pellet plasmas.