Gyrokinetic Simulation Of Fast-electron Driven Beta-induced Aflven Eigenmodes

The goal of magnetic confined fusion is to solve the global energy problem in the long future. The fusion energy has the advantage of cleanness and abundance of fusion sources. Tokamak is believed to be one of the most promising candidate to achieve this goal. In Tokamak,the Alfven modes will cause the fast particles lost and the fast parti-cles will damage the first wall of the fusion device. Thus, it is necessary to investigate the Alfven waves in Tokamak.The fast-electron driven beta-induced Alfven eigenmode (e-BAE) in toroidal plas-mas is investigated for the first time using global gyrokinetic particle simulations, where the fast electron is described by the drift kinetic equation. The simulation shows that the e-BAE propagates in the fast-electron diamagnetic direction and its polarization is close to an ideal MHD mode. The phase space structure shows that only the fast electron processional resonance is responsible for the e-BAE excitations while fast-ion driven BAE can be excited through all the channels including transit, bounce, and processional resonance.Then we investigate the nonlinear e-BAE. In weakly driven cases, we demonstrate a chirping phenomenon. Through the phase space of the fast electron perturbed distri-bution function shows a clear clump-hole structure in phase space, and more particles participate in the resonance. Test particles' orbit in (?,P?) phase space shows that the resonance island's evolution is related to the chirping phenomenon. In strong driven cases, the BAAE (?-induced Alfven-acoustic eigenmodes) frequency occurs. We in-vestigate the mode structure and the phase space of distribution function and prove that the frequency exactly exists.