Discrete Alfvén eigenmodes in international thermonuclear experimental reactor operations with negative magnetic shear

Discrete Alfvén eigenmodes in steady-state operation scenarios with negative magnetic shear in the international thermonuclear experimental reactor are investigated in this paper. These magnetohydrodynamic eigenmodes are trapped by the \alpha -induced potential wells along the magnetic field line. Here \alpha=-q^2R\rm d\beta/\rm dr with q being the safety factor, \beta the ratio between plasma and magnetic pressures, and R the major radius, and r the minor radius. Due to negligible continuum damping via wave energy tunneling, these Alfvén eigenmodes could be readily destabilized by energetic particles.