Electron acceleration and optical guiding in the laser wakefield accelerator

The laser wakefield acceleration concept is studied using a general 2D formulation based on relativistic fluid equations. Simulations of an intense laser pulse propagating in a plasma address both optical guiding and wakefield generation issues. The ponderomotive forces associated with the laser pulse envelope expels virtually all of the plasma electrons, resulting in the generation of large amplitude accelerating and focusing fields. It is shown that relativistic guiding is ineffective in preventing the diffraction of short pulses and long pulses are broken up into beamlet segments due to wakefield effects. The use of preformed plasma density channels or tailored pulse profiles allows intense laser propagation over many Rayleigh lengths. Large amplitude wakefields can be generated over long distances in these cases and are suitable for electron trapping, acceleration, and focusing