  Hybrid MHD-gyrokinetic code simulations are used to investigate the dynamics
of frequency sweeping reversed shear Alfv\'en eigenmode (RSAE) strongly driven
by energetic particles (EPs) during plasma current ramp-up in a conventional
tokamak configuration. A series of weakly reversed shear equilibria
representing time slices of long timescale MHD equilibrium evolution is
considered, where the self-consistent RSAE-EP resonant interactions on the
short timescale are analyzed in detail. Both linear and nonlinear RSAE dynamics
are shown to be subject to the non-perturbative effect of EPs by maximizing
wave-EP power transfer. In linear stage, EPs induce evident mode structure and
frequency shifts; meanwhile, RSAE saturates by radial decoupling with resonant
EPs due to weak magnetic shear, and gives rise to global EP convective
transport and non-adiabatic frequency chirping. The spatiotemporal scales of
phase space wave-EP interactions are characterized by the perpendicular
wavelength and wave-particle trapping time. The simulations provide insights
into general as well as specific features of RSAE spectra and EP transport from
experimental observations, and illustrate the fundamental physics of wave-EP
resonant interaction with the interplay of magnetic geometry, plasma
non-uniformity and non-perturbative EPs.
