Field coherence in laser-assisted charged-particle scattering

Abstract

The problem of charged-particle scattering in the presence of strong laser fields is investigated within a treatment in which the effect of the assisting field is included exactly, to all orders. Two laser field models are considered: 1) the model of a purely coherent field and 2) that of a field with well-stabilized amplitude and fluctuating phase (phase diffusion model, PDM). The scattering cross-sections are numerically investigated for selected but representative values of the parameters of the problem. Differential and total cross-sections are evaluated as functions of the scattering angles, the incident energy, the field coherence and intensity and the number of exchanged photons. The band width of the PDM field is found to affect significantly the scattering parameters, especially in the case of differential cross-sections and of high intensities. As compared to the purely monochromatic (SM) field, the PDM field is found to exhibit oscillations of smaller amplitudes with a tendency to a smooth behaviour with increasing band width, photon multiplicity and intensity. The PDM cross-sections are generally slightly larger than the SM ones. For the first time are reported calculations of the total cross-sectionsvs. the intensity with a sufficiently large density of points to resolve accurately the oscillatory structure of the high-intensity portion of the cross-sections. A consequence ensuing from the exact treatment of the laser field is that the field coherence properties too are treated exactly, at least within the given laser models, and it is expected to be of importance beyond the particular problem treated here, especially when nonresonant processes are concerned.