Simulation Of Interaction Between Energetic Particles And MHD Waves On EAST

Energetic particles(EPs)generated by fusion reactions and/or auxiliary heating can destabilize the MagnetoHydroDynamic(MHD)modes(such as Alfven eigenmodes and energetic particle mode),which can cause loss of EPs,thus reducing the efficiency of plasma heating.Therefore,the excitation of MHD waves by EPs and the interaction between them are important topics in magnetic confinement fusion plasmas.In this work,kinetic-MHD hybrid simulations are carried out to investigate the in?teraction between energetic ions and TAE and the interaction between energetic ions and fishbone mode on Experimental Advanced Superconducting Tokamak(EAST)by us?ing kinetic-MHD hybrid code MEGA.The TAE excited by energetic ions generated by neutral beam injection(NBI)is investigated by using MEGA code,based on a realistic equilibrium reconstructed from NBI heating discharge of EAST.The linear benchmark between two kinetic-MHD codes,namely MEGA and M3D-K is carried out.Param?eter scans show that the TAE frequency and growth rate given by the two codes agree with each other in the EAST NBI parameter regime.The simulation results show that the TAE exchanges energy with the co-current passing particles with parallel velocity|vⅡ|≈VA0/3.The TAE destabilized by the counter-current passing ions is also ana-lyzed and found to have much smaller growth rate than the co-current ions driven TAE.Kinetic-MHD hybrid simulations are also carried out to investigate fishbone modes ex-cited by energetic ions on the EAST,based on a realistic equilibrium of NBI heating discharge of EAST which observed fishbone mode.Early analytical studies consider the trapped EPs or passing EPs only.In this work,slowing down distribution is used to model energetic ions generated by NBI,which contains both trapped and passing energetic ions.Simulation results show that both the passing and trapped particles are important in destabilizing the fishbone mode.Nonlinear simulation results show that the mode frequency chirps down as the mode reaches the nonlinear stage,during which there is a substantial flattening of the perpendicular pressure of energetic ions,compared with that of the parallel pressure.In the saturation stage,it is mainly the trapped ener-getic ions being interact with the fishbone mode and the resonant location of trapped EPs moves out radially.The saturation level given by the MEGA code is consistent with the EAST experimental observation.The dependence of the growth rate and frequency of fishbone on EPs parameters is consistent with the previous study.The benchmark between MEGA and M3D-K codes provides the basis for further applications of the two codes on EAST.The simulation of the interaction between en-ergetic ions and MHD waves provides a theoretical reference for f-urther experimental research.