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

Results of the electron cyclotron current drive experiment at the second harmonic resonance on the T-10 tokamak are presented. High frequency (HF) power up to 1.2 MW was launched from the low field side. A maximum driven current of 35 kA and current drive efficiency eta(CD) = 0.05 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 effect of the elliptical polarization from non-perpendicular injection is considered, in which case the efficiency is close to the theoretical value. The experimental dependence of eta(CD) on the absorbed HF power indicated a strong increase of eta(CD) with power. Suppression of sawtooth oscillations and improvement of confinement during electron cyclotron heating has also been demonstrated.