Experimental observation of ion heating by mode-converted ion Bernstein waves in tokamak plasmas

We report the experimental observation of ion heating by the mode-converted ion Bernstein waves (MC IBWs) in tokamak plasmas. The MC IBW is created from the fast waves launched from the high-field-side antenna in the HT-7 tokamak in plasmas consisting of deuterium majority, hydrogen minority and 7Li ions. Experimental evidence and numerical simulation show that the interaction between the MC IBW and 7Li ions at the first ion-cyclotron harmonic resonance of 7Li (i.e. ω = 2ΩLi-7) is the main mechanism for radio-frequency power deposition. By comparing with previous experiments of direct-launch IBW flow drive on tokamaks and existing theories, we hypothesize that this MC IBW and 7Li interaction also leads to the observed flow drive effect. (letter)