  Collisional effects can play an essential role in the dynamics of plasma
waves by setting a minimum damping rate and by interfering with wave-particle
resonances. Kinetic simulations of the effects of electron-ion pitch angle
scattering on Electron Plasma Waves (EPWs) are presented here. In particular,
the effects of such collisions on the frequency and damping of small-amplitude
EPWs for a range of collision rates and wave phase velocities are computed and
compared with theory. Both the Vlasov simulations and linear kinetic theory
find the direct contribution of electron-ion collisions to wave damping is
about a factor of two smaller than is obtained from linearized fluid theory. To
our knowledge, this simple result has not been published before.
  Simulations have been carried out using a grid-based (Vlasov) approach, based
on a high-order conservative finite difference method for discretizing the
Fokker-Planck equation describing the evolution of the electron distribution
function. Details of the implementation of the collision operator within this
framework are presented. Such a grid-based approach, which is not subject to
numerical noise, is of particular interest for the accurate measurements of the
wave damping rates.
