LAUSR

The spectrum effects on toroidal rotation braking, induced by n = 1 resonant magnetic perturbations (RMPs) in the discharges with q95=4.1 and q95=5.1 , are studied in the EAST tokamak. Here n is the toroidal mode number, RMP spectrum is varied by scanning δϕUL , the phase difference between the upper and lower rows of RMP coils. The toroidal rotation changes periodically with the periodic δϕUL scanning and such an effect is stronger in the discharge with lower q95=4.1 . The spectrum dependence of the neoclassical toroidal viscosity (NTV) torque, modeled by NTVTOK based on the magnetic perturbation obtained from MARS-F calculation, agrees well with that of the experimentally observed braking torques in both discharges. The modeled NTV torque is stronger in the discharge with lower q 95, which also agrees with the observations. The comparisons between the spectrum dependence of the NTV and magnetic perturbations show that the resonant mode of magnetic perturbations near the plasma edge mainly contribute the NTV torque. These agreements between modeling and experiments highlight the capability of NTV theory in explaining the experimental observation in the EAST tokamak.