Kinetic effects of thermal ions and energetic particles on discrete kinetic BAE mode generation and symmetry breaking

摘要

The kinetic effects of both thermal ions and energetic particles (EPs) on global Alfven mode generation and structure symmetry breaking are important for the understanding of resonant excitation and EP transport in tokamak plasmas. In this work, the formulation for the study of the beta induced Alfven eigenmode (BAE) driven by EPs is derived for weakly coupled poloidal harmonics with finite Larmor radius (FLR) and finite orbit width (FOW). Agreement between the theoretical model and corresponding XHMGC simulations is demonstrated. It is shown that including FLR and FOW can lead to the global mode structure broadening. The non-perturbative effects of the energetic particles on global mode structure symmetry breaking is demonstrated. In particular, when the energetic particle drive shifts away from the mode rational surface, volume averaged parallel and radial wave numbers are generated in the plasma as a demonstration of EPs' role on mode structure symmetry breaking. The connection of the mode structure symmetry breaking with experimental observations using ECEI and with particle/momentum transport are discussed.