Stimulated processes and self-modulation of a short intense laser pulse in the laser wake-field accelerator

Abstract

The basic equations for self‐consistent pulse evolution taking into account stimulated Raman backward and near‐backward scattering are formulated. These equations are used to study the three‐dimensional (3‐D) axisymmetrical self‐consistent laser pulse evolution analytically and numerically. Special attention is paid to the case of the pulse self‐modulation. The spectra and intensity of backscattered radiation are obtained in both the strong and weak coupling limits. A simple criterion to ignore the action of stimulated Raman backscattering on the pulse evolution is derived. The possibility of using a backscattered radiation spectrum for diagnostics of both the laser‐pulse and generated wake‐field evolution is discussed. Triggering of the laser‐pulse self‐modulation by the relativistic self‐focusing and by a second frequency‐shifted weak‐intensity laser pulse is discussed. Basing on the obtained results, a new configuration of stimulation and maintaining a strong wake‐field excitation is proposed. This configuration makes it possible to obtain acceleration of electrons up to giga‐electron‐volt energies in the field of the excited plasma wave by using the laser technology that is presently available.