LOWER HYBRID CURRENT DRIVE EXPERIMENTS IN THE HT-6M TOKAMAK

Lower hybrid current drive (LHCD) experiments with a multijunction grill have been performed in the HT-6M tokamak. When the RF power pulse with 15ms risetime is injected into the plasma. the toroidal current amplitude is raised, but the temporal variation of the loop voltage does not have measurable change. The efficiency of current drive is I_rf/ P_rf=0.57kA/kW at n_e =3x10¹²cm^-3 and B_t=8KG. It seems that the multijunction grill has the same efficiency as the ordinary grill on the LHCD experiments.