Injection, trapping, and acceleration of electrons in a three-dimensional nonlinear laser wakefield

It is demonstrated that the accelerating and focusing phases of the nonlinear three-dimensional axisymmetric laser wake can almost entirely overlap starting from a certain distance behind the laser pulse in homogeneous plasma. Such field structure results from the curvature of phase fronts due to the radially inhomogeneous relativistic shift of plasma frequency. Consequently, the number of trapped low-energy electrons can be much greater than that predicted by the linear wake theory. This effect is favorable for quasimonoenergetic acceleration of a considerable charge (several hundreds of pC) to about 1GeV per electron in the plasma wakefield driven by an ultrashort (∼30fs) weakly focused (r0∼100μm) petawatt laser pulse.