Few-cycle-laser-pulse-assisted electron-ion radiative recombination

Abstract

Electron-ion radiative recombination assisted by a few-cycle laser pulse is analyzed in the frame of the $S$-matrix theory. The result obtained in the first Born approximation corresponds to the direct recombination of electrons with ionic targets, while the result in the second Born approximation corresponds to the recombination preceded by electron-ion scattering. Driven by the laser pulse, the once scattered electron may return to the same ion and recombine with it. The x-ray photon emitted in such a process may have high energies. The dependence of the energy spectrum on various parameters, such as the carrier-envelope phase, peak intensity, and duration of the laser pulse, and the incident electron energy and angle, is investigated. The abrupt cutoffs of the plateau structures in the energy spectra of the process are explained by classical analysis.