Laser-assisted radiative recombination and X-ray generation

We investigate electron-ion recombination in a powerful laser field. During this process a certain number of laser photons can be absorbed or emitted yielding a spectrum of harmonics of the form omega (X) = E-p + n omega (L) + I-io + U-p where E-p is the initial electron energy, n the number of emit ted or absorbed laser photons omega (L), I-io the ionization energy and U-p the ponderomotive energy of the laser field. As it turns out, the maximum energy that can be absorbed from the laser field during the recombination i s given by n(max)omega (L) = 2 root 2U(p)E(p). This process is of interest for the generation of high frequency fields during the laser heating of pla smas. We shall evaluate the nonlinear recombination probabilities using the inverse form of the Keldysh-Faisal-Reiss model, taking also into account i n an approximate way the Coulomb effects of the ion on the recombining elec tron.