A thorough investigation of confinement in Frascati Tokamak Upgrade has been carried out on a new database of ohmic, L-mode and advanced scenario discharges (multiple pellet-fuelled, radiation improved and internal transport barriers (ITBs)) obtained with the available auxiliary heating systems, namely electron cyclotron resonant heating, lower hybrid and ion Bernstein wave. A general agreement of the measured τE with ITER97 L-mode scaling is found in ohmic and L-mode discharges. An improvement of the energy confinement time (τE) of up to about 60% over the ITER97 L-mode scaling has been obtained in ITB discharges, together with a reduction in local electron transport in the region of high pressure gradient, and up to about 30% in pellet-fuelled discharges (where τE as large as ∼120 ms have been reached). The linear density dependence of τE in ohmic discharges has been found to extend above the saturation density threshold in pellet-fuelled plasmas.
Power threshold and confinement of the I-mode in the EAST tokamak