  A numerical fluid simulation investigation of the temporal evolution of a
special class of traveling wave solution of the one dimensional relativistic
cold plasma model is reported.The solutions consist of coupled electromagnetic
and plasma waves in a solitary pulse shape (Phys. Rev. Lett. 68, 3172(1992);
Phys. Plasmas 9, 1820(2002)).Issues pertaining to their stability, mutual
collisional interactions and propagation in an inhomogeneous plasma medium are
addressed. It is found that solitary pulses that consist of a single light peak
trapped in a modulated density structure are long lived whereas structures with
multiple peaks of trapped light develop an instability at the trailing edge.
The interaction properties of two single peak structures show interesting
dependencies on their relative amplitudes and propagation speeds and can be
understood in terms of their propagation characteristics in an inhomogeneous
plasma medium.
