Radially localized kinetic beta induced Alfven eigenmodes in tokamak plasmas

Abstract

We have studied the kinetic beta induced Alfven eigenmodes (KBAEs) by developing a fast global eigenvalue solving code. Even and odd parity KBAEs radially localized at the rational surface are found with the presence of the kinetic effects, namely, the finite ion Larmor radius effects. The KBAE mode structures become broader in the presence of the parallel equilibrium current. The KBAE frequency increases with the increase in the plasma β and the ion Larmor radius (ρi). Damping of the KBAE increases with the finite Larmor radius and decreases with the plasma beta and mode with a higher radial mode number has a stronger damping. Numerical results reveal that frequency and kinetic damping of KBAEs are independent of the tokamak size, and that kinetic damping in the core region is significantly smaller by an order of magnitude compared to that in the radially outward region of tokamak.