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

TL;DR

This paper proposes a nonlinear saturation mechanism for reversed shear Alfven eigenmodes involving high-frequency quasi-mode generation, relevant to reactor conditions, and provides an estimation of the damping rate.

Contribution

It introduces a novel nonlinear saturation process for RSAEs through quasi-mode generation and damping, expanding understanding of plasma behavior in reactors.

Findings

High-frequency quasi-modes are generated via nonlinear coupling of RSAEs.

The quasi-modes are damped through coupling with the shear Alfven continuum.

A nonlinear damping rate is estimated for the saturation process.

Abstract

A nonlinear saturation mechanism for reversed shear Alfven 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 Alfven continuum, and leads to the nonlinear saturation of the primary RSAEs . An estimation of the nonlinear damping rate is also provided.