  Alfv\'enic modes in the current quench (CQ) stage of the tokamak disruption
have been observed in experiments. In DIII-D the excitation of these modes is
associated with the presence of high-energy runaway electrons, and a strong
mode excitation is often associated with the failure of RE plateau formation.
In this work we present results of self-consistent kinetic-MHD simulations of
RE-driven compressional Alfv\'en eigenmodes (CAEs) in DIII-D disruption
scenarios, providing an explanation of the CQ modes. Simulation results reveal
that high energy trapped REs can have resonance with the Alfv\'en mode through
their precession motion, and the resonance frequency is proportional to the
energy of REs. The mode frequencies and their relationship with the RE energy
are consistent with experimental observation. The perturbed magnetic fields
from the modes can lead to spatial diffusion of runaway electrons including the
nonresonant passing ones, thus providing the theoretical basis for a potential
approach for runaway electron mitigation.
