In this scenario the ECRH experiments have produced very high peak electron temperature, up to 14 keV for 690 kW injected power, Fig. 2. It has been checked that the results are consistent with the MHD behaviour of the discharges, that has been studied extensively.
Shaded area indicate the uncertainty on the diffusivity value .
In the more external plasma region the local analysis is made difficult by the role of the radiation and the uncertainty on the ohmic power evaluation in the transient conditions characterising the fast current ramps. In the case of a hollow initial current profile, Fig. 4, the temperature profile remains hollow during the ECRH, showing a trend to become flat in the region inside the ECRH deposition layer. This behaviour can be considered as the mark of an underlying diffusive transport mechanism that can be described by a local thermal diffusivity. In the case of plasma discharges having peaked pre-ECRH profiles, the electron temperature profile remains peaked, Fig. 5. This behaviour could be explained by the effect of the residual ohmic heating.