Global theory of beta-induced Alfven eigenmode excited by energetic ions

The two-dimensional global stability and mode structures of high-n beta-induced Alfven eigenmodes excited by energetic ions in tokamaks are examined both analytically and numerically, employing the WKB-ballooning mode representation along with the generalized fishbone like dispersion relation. Here, n >> 1 is the toroidal mode number. Our results indicate that (i) the lowest radial bound state corresponds to the most unstable eigenmode, and (ii) the anti-Hermitian contributions due to wave-energetic particle resonance give rise to the twisting radial mode structures. (C) 2015 AIP Publishing LLC.