Effect of Electron Cyclotron Current Drive on the Ion Temperature in the Plasma Core Region of the Large Helical Device

Abstract

An indirect effect of the electron cyclotron current drive (ECCD) on the ion temperature in the plasma core region was observed in the Large Helical Device. The reference (no ECCD) discharge with a central ion temperature T_i0 of ∼3.0 keV is operated by a standard high ion temperature discharge procedure. To investigate the ECCD effect, a co- or counter-ECCD was applied to the reference discharge, and was turned off immediately before the T_i0 peaked in the reference discharge. In the co-ECCD and counter-ECCD applications, the T_i0 temporarily increased and decreased by ∼0.5 keV from T_i0 in the reference discharge, respectively. The mechanism of this phenomenon is presently unclear, but may be exploited as a practical knob for controlling the central ion temperature.