Time: 2014-11-05 14:00:00
Speaker: Chen Zhao, Ruirui Ma [IFTS-ZJU]
Place: Rm. 413, Bld. 11#, Yuquan Campus
Abstract:
Ruirui Ma
Title:Global analysis of beta-induced Alfven eigenmode excited by energetic ions
Abstract:By using a WKB-ballooning analysis and taking a set of governing equations, a global dispersion relation for high-mode-number beta-induced Alfven eigenmodes (BAEs) in large aspect-ratio, finite-β tokamaks is obtained for analyzing two-dimensional structures of BAE excitation by a radially localized energetic ion beam. The finite θk = (nq’)-1kr, normalized local radial wave vector, modifying the generalized fishbone-like dispersion relation is derived based on previous work. It is shown that in the absence of the energetic particles the finite θk can lead to a substantial stabilizing effect on the BAE which has an up-down symmetric radial mode structure for an up-down symmetric tokamak equilibrium. However, such symmetry is broken in the presence of energetic particle resonant drive, which can be attributed to the anti-hermitian part of the BAE dispersion relation. The analytic results of the poloidal mode structure of the BAE agree with the previous numerical simulations.