Nonlinear simulations of Alfv\'enic instabilities driven by energetic particles in a reversed shear tokamak plasmas

The extended version of nonlinear hybrid magnetohydrodynamic (MHD)-Gyrokinetic code HMGC~\footnote{S. Briguglio {\sl et al.}, Phys. Plasmas {\bf 2} 3711 (1995).}(XHMGC) is used to investigate the reversed shear Alfv\'en eigenmodes (RSAE)/energetic particle modes (EPM) driven by an anisotropic Maxwellian energetic particles with reversed shear q profiles. In the region near the minimum-q surface, EPM are shown to exist inside the kinetic low-frequency shear Alfv\'en continuum gap. Fast non-adiabatic down-ward chirping frequency is found for given equilibrium profiles, which is understood as consequence of nonlinear wave particle dynamics. In our current case, the mode structure is dominated by two neighbor poloidal components, while wave energetic particle interaction is dominated by the sidebands of the dominant transit resonance.