Nonlinear saturation of reversed shear Alfvén eigenmode via high-frequency quasi-mode generation

A nonlinear saturation mechanism for reversed shear Alfvén eigenmode (RSAE) is proposed and analysed, and is shown to be of relevance to typical reactor parameter region. The saturation is achieved through the generation of high-frequency quasi-mode due to nonlinear coupling of two RSAEs, which is then damped due to coupling with the shear Alfvén continuum, and leads to the nonlinear saturation of the primary RSAEs . An estimation of the nonlinear damping rate is also provided.