The effect of applied n <b>=</b> 1 resonant magnetic perturbations on energetic particle losses in a tokamak

This paper presents a numerical simulation of the loss of energetic particles (EPs) induced by resonant magnetic perturbations (RMPs) in the EAST tokamak, specifically for the case where q95&amp;lt;3.5. The loss of EPs generated by neutral beam injection due to the n=1 RMPs is simulated. The results indicate that the n=1 RMPs can cause significant losses of EPs. These lost EPs are distributed in both the toroidal and poloidal directions below the midplane, potentially resulting in additional thermal load to the first wall of the device. The main lost particles are passing ions. Three mechanisms resulting in the EP losses are identified, namely, the RMP-induced prompt loss, the resonant loss, and the orbit-transition loss. The kinetic Poincaré plots show the nonlinear resonant interactions with the ratio of poloidal bounce frequency to toroidal transit frequency of EP being 5/2 and 7/3. The passing particles in the certain region of the phase space can be pushed by the RMPs to the lost trapped region. Varying the phase of RMP also influences EP transport, and there may be an optimal RMP phase that minimizes EP loss. Finally, the analysis of various parameters indicates that varying the RMP amplitude significantly affects the loss of EPs through the resonant interactions. Once the RMP amplitude exceeds a critical threshold, the EP losses increase rapidly. Furthermore, the effects of different poloidal components of the magnetic perturbation on the loss of EPs exhibit similar trends. An increase in the number of the poloidal components of the magnetic perturbation enhances the EP losses and lowers the magnitude of the loss threshold.