Plasma heating by injection of neutral beams into TFR 600

Experimental results from quasi-perpendicular high power (up to 1.2 MW) neutral beam injection in the TFR 600 Tokamak are reported. The trapped fast ions show all the characteristics of a classical feature. This allows us to study the behaviour of a dense plasma (n approximately equal to 1014 cm-3) whose electron and ion temperatures are significantly changed by fast neutrals injection (Δ Tsub(e,i) > 300 eV). No increase of the global energy confinement time has been observed, but at low q value a large increase of internal disruptions appears. This fact permits to partly enlighten the internal disruptions mechanism and to emphasize their importance. 1-D simulation calculations are also reported; changes in the the electron and ion heat conduction, necessary to explain most of the experimental results observed during the internal disruptions will be discussed