Zero frequency zonal flow excitation by energetic electron driven beta-induced Alfven eigenmode

Zero frequency zonal flow (ZFZF) excitation by trapped energetic electron driven beta-induced Alfven eigenmode (eBAE) is investigated using nonlinear gyrokinetic theory. It is found that, during the linear growth stage of eBAE, resonant energetic electrons (EEs) not only effectively drive eBAE unstable, but also contribute to the nonlinear coupling, leading to ZFZF excitation. The trapped EE contribution to ZFZF generation is dominated by EE responses to eBAE in the ideal region, and is comparable to thermal plasma contribution to Reynolds and Maxwell stresses.
Comment: submitted to Plasma Physics and Controlled Fusion (2020)