Particle injection into the wave acceleration phase due to nonlinear wake wave breaking

We present analytical results and computer simulations of the nonlinear evolution of wake field waves in inhomogeneous plasmas. The wake wave break that occurs due to the inhomogeneity of the Langmuir frequency makes it possible to inject electrons into the acceleration phase of the wave. Particle-in-cell simulations show that stable beams of energetic electrons are formed. These beams are well bunched in coordinate and velocity space and contain a considerable fraction of the pulse energy