Additional heating and reversed magnetic shear in the FTU tokamak

摘要

After one year of shutdown devoted to the installation of the toroidal molybdenum limiter, the Frascati Tokamak Upgrade (FTU) has recently resumed operation. The experimental programme is focused on the three radiofrequency (RF) heating and non-inductive current drive systems: electron cyclotron resonant heating (ECRH), lower hydrid current drive (LHCD) and ion Bernstein wave heating (IBWH). The main aim of the experiments reported here is to demonstrate LHCD at high density and to sustain and heat reversed magnetic shear configurations, with a large reversal radius (r_s/a approx approx 0.5). A transient heating of the shear reversed discharges achieved in ohmic conditions has been performed through ECRH. The results show that good confinement properties are maintained within the shear reversal surface.