(color online) The evolutions of electron density and corresponding D_α signals during SMBI pulses in shot #9940 on HL-2A. (a) and (b) The evolutions of line-averaged electron density and D_α signals during SMBI pulses, respectively. (c) and (d) the evolutions of line-averaged electron density and D_α signals during the first SMBI pulse, respectively. (e) the controlling signal of the first SMBI pulse. (f) contour plot for FC and a part of SC. Reprinted from Ref. [23] with permission.