The effect of resonant magnetic perturbation with different poloidal mode numbers on peeling–ballooning modes

The effect of resonant magnetic perturbation (RMP) with different poloidal mode numbers on peeling– ballooning (P–B) modes is simulated with the BOUT++ code. In order to investigate the physical mechanism of edge-localized mode mitigated by RMP, a series of RMPs with different poloidal mode numbers are applied into the four-field P–B mode simulation module separately. The results indicate that RMP has a better reducing effect on the energy loss from the pedestal when the resonant position is near the bottom and top of pedestal rather than near the middle. The RMP could influence P–B modes through the following effects: on the one hand, the E × B shearing rate is significantly stronger when the RMP (resonant surface locates at the top of the pedestal) is added, which can suppress the radial propagation of the negative pressure perturbation and reduce energy loss from the pedestal. On the other hand, the coupling of toroidal modes in the nonlinear phase is enhanced when RMPs are added, which motivated the growth of multiple toroidal modes, and the turbulence fluctuation level is weaker with the RMP when the resonant surface is located at the bottom of the pedestal.