Extensive studies of a steady-state tokamak reactor have been carried out on the superconducting tokamak TRIAM-1M. A discharge of lasting more than 2 h has been demonstrated using a 2.45 GHz lower hybrid current drive (LHCD). A high-density plasma of has been sustained for 1 min using a 8.2 GHz LHCD under the high average wall loading of on the limiter. Recently, a single-null divertor configuration with high elongation was also successfully maintained for 1 min by the 2.45 GHz LHCD. A transition of the ion temperature from 0.6 keV to about 2.5 keV is observed in 2.45 GHz LHCD plasmas; this operational regime is called the `high ion temperature (HIT)' mode. The `HIT' mode is characterized by the existence of a steep gradient near . It is found that the `HIT' mode appears in a narrow window of the electron density and horizontal plasma position. The `HIT' mode can be successfully maintained for over 1 min with accurate control of the density and position.
First results of LHCD experiments with 4.6 GHz system toward steady-state plasma in EAST