Abstract. Abstract Enhancement of current drive (ECD) efficiency mode, which is characterized by the spontaneous increase of current drive efficiency, , from 0.3 - 0.4×1019A/Wm- 2 to 0.7 - 1.0×1019A/Wm- 2, is observed in long pure lower hybrid current drive (LHCD) plasmas on TRIAM-1M. The energy confinement time is also improved due to the increase of line averaged electron density, ion and electron temperatures. The current drive efficiency is proportional to the electron density. The transition to ECD mode occurs at a critical density, which slightly depends on the refractive index to the toroidal direction, N| of the injected wave.
IAEA 2001