  The process of wake fields excitation by a relativistic electron bunch in ion
dielectric media is considered. The space-time structure of the excited
wakefield in an ion dielectric waveguide is investigated. It is shown that the
wake field in the infrared (terahertz) ranges consists of the field of
longitudinal polaritons and Cherenkov radiation, which is a set of
electromagnetic eigen waves (transverse polaritons) of a dielectric waveguide.
A branch of surface polaritons appears in a dielectric waveguide with an axial
vacuum channel. The process of wakefield excitation of surface polaritons by a
relativistic electron bunch is also considered.
