Observation of the limiter H mode in the JT-60 tokamak with lower-hybrid current drive

The H mode was achieved in limiter discharges of a tokamak with lower-hybrid current drive for the first time. Simultaneous application of rf powers at two different frequencies such as 1.74 and 2.23 GHz or 1.74 and 2.0 GHz appeared to be effective in the attainment of the H mode. The threshold lower-hybrid power was as low as Ohmic-heating power with hydrogen plasmas. A nearly steady-state edge-localized-mode-free H mode with a duration up to 3.3 sec was established without significant impurity accumulation.