Experimental investigation of the interaction of IBW and LHCD in the HT-7 tokamak

Experiments of simultaneous injection of LHWs and IBWs into plasmas have been conducted in the HT-7 tokamak. Evidence that IBW can control the plasma pressure profile was observed in LHCD plasmas. It was found that electron Landau damping (ELD) of IBWs occurred around the maxima of parallel refractive index, n∥, and that the ion cyclotron resonant layer can enhance off-axis LHW power deposition and create a localized fast electron current channel. But the global LHCD efficiency during an IBW pulse was not improved obviously. As a result of the localization of LHCD during an IBW pulse, the global current density profile was modified, which was indicated by the internal inductance, l_i. Optimization of this operation mode utilizing the features of the interaction of IBWs and LHCD provides a new way of obtaining a high performance plasma under steady-state conditions.