ICRF Mode Conversion Flow Drive on Alcator C-Mod

ICRF mode conversion flow drive (MCFD) may be a candidate for the external control of plasma rotation in large tokamaks like ITER. Recently, we have carried out a detailed study of MCFD on C-Mod, including its dependence on plasma and RF parameters [1]. The observed change in the toroidal rotation ($\Delta $V) is always in the co-I$_{p}$ direction. The flow drive efficiency depends on the $^{3}$He concentration in D($^{3}$He) plasmas. It is strongly affected by density ($\sim $ 1/n$_{e})$, generally increases with I$_{p}$ and decreases with RF frequency. At +90$^{o}$ and dipole antenna phases, we find that $\Delta $V is proportional to P$_{RF}$ up to the maximum available RF power. The rotation at -90$^{o}$ antenna phase is more complicated. In low density L-mode plasmas, $\Delta $V $\sim $110 km/s has been achieved. Results in H-mode plasmas appear to follow a similar parametric scaling, but the observed $\Delta $V in H-mode has been small because of the high density and unfavorable 1/n$_{e}$ scaling. These results may help extrapolate MCFD to other fusion devices.\\[4pt][1] Y. Lin et al, 23$^{rd}$ IAEA Fusion Energy Conference, 2010, EX-W/4-1.