Speaker
Description
Abstract: In tokamak plasmas, energetic particles (EPs) produced by heatings and fusion reactions can drive Toroidal Alfvén eigenmodes (TAEs) and Energetic particle modes (EPMs), which affect the plasma performance. We perform an eigen-analysis of AEs using the code AWEAC (Alfvén Wave Eigen-Analysis Code) and simulation using the MEGA code on the EAST #38300 discharge. The linear simulations with MEGA are consistent with the AWEAC eigen-analysis results for the TAE radial location, frequency and the poloidal components. The results of EP distribution function variations are consistent with the 2D mode structure, the Fourier components and the resonance behavior in phase space. The TAE and EPM transition due to viscosity or EP beta is analyzed by contributions of passing/trapped and co/counter particles. For strong TAE/EPM, the long-time nonlinear behaviors, such as the frequency sweeping, are also closely related to the interactions of EPs and TAEs/EPMs. The simulations of CFETR TAE/EPM driven by NBI generated energetic ion and fusion generated alpha particle are also performed. With the increases of magnetic shear, the strength and radial location of TAE/EPM changes. These studies of TAEs/EPMs can help understand the long pulse discharges for EAST, as well as the design of baseline and hybrid scenarios for CFETR.