Semiclassical theory of laser-assisted radiative recombination

摘要： We study the process of laser-assisted radiative recombination of an electron with a proton by using a semiclassical approach involving calculation of classical trajectories in combined laser and Coulomb fields. Due to chaotic scattering in the combined fields, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits chaotic behavior and fractal structures. We obtain a strong enhancement of the recombination cross section as compared to the laser-free case due to the Coulomb focusing effect. For sufficiently low incident electron velocities the cross section becomes infinite, and we limit it by assuming a finite laser pulse duration. With the pulse duration tp = 5 ps we obtain the gain factor for capture into the ground state of the hydrogen atom of about 220 for infrared fields in the intensity range 109–1012 W/cm2. The gain factor grows with tp but slower than linearly.