Energy confinement and plasma heating during lower hybrid experiments

RF power up to 450 kW has been injected into the plasma of FT in the electron heating regime (n_e<or=5*10¹³ cm^-3) producing electron and ion temperature increases of about 1 keV and .5 keV respectively without significant enhancement of Z_eff. A density increase is observed due to an improvement of particle confinement time. An energy balance at intermediate power levels (P_RF=300 kW) is carried out for two different types of discharges, one without sawteeth the other with sawteeth. The balance shows that in order to account for the total injected power one has to assume equal electron thermal conductivity for the OH and the OH+RF phase. The energy confinement time does not vary from its ohmic value for both discharges. Finally an investigation, at n_e above the density limit, of the radial source of the fast ion tails and of the characteristics of the parametric decay instability is presented.