Generation of rf-Driven Currents by Lower-Hybrid-Wave Injection in the Versator II Tokamak

Experimental verification of lower-hybrid rf current drive in the Versator II tokamak is presented. The experiments show that efficient current drive exists only in low-density discharges (n̄ₑ6×10¹² cm^-3) in the "slide-away" regime where a preformed suprathermal electron tail exists prior to the application of the rf power.