Laser acceleration of charged particles in inhomogeneous plasmas II: Particle injection into the acceleration phase due to nonlinear wake wave-breaking

Results from analytical studies and computer simulations of the nonlinear evolution of wake waves in inhomogeneous plasmas are presented. It is shown that the wake wave-breaking that appears due to the inhomogeneity of the Langmuir frequency can be used to inject electrons into the acceleration phase of the wave. In the wake wave excited behind a finite-width laser pulse, the wave-breaking mechanism involves the increase in the curvature of the wake front with the distance from the pulse, followed by the self-intersection of the electron trajectories.