SECOND-HARMONIC ELECTRON-CYCLOTRON CURRENT DRIVE EXPERIMENTS ON T-10

Results of the electron cyclotron current drive experiment at the seco nd harmonic resonance on the T-10 tokamak are presented. High frequenc y (HF) power up to 1.2 MW was launched from the low field side. A maxi mum driven current of 35 kA and current drive efficiency eta(CD) = 0.0 5 A/W at an electron temperature T-e(0) = 4 keV and a density n(e)(0) = 1 x 10(13) cm(-3) were obtained. For low HF power, the current drive efficiency was less than predicted by the linear theory unless the ef fect of the elliptical polarization from non-perpendicular injection i s considered, in which case the efficiency is close to the theoretical value. The experimental dependence of eta(CD) on the absorbed HF powe r indicated a strong increase of eta(CD) with power. Suppression of sa wtooth oscillations and improvement of confinement during electron cyc lotron heating has also been demonstrated.