Non-relativistic non-dipole two-photon bremsstrahlung in a Coulomb field

We present analytical and numerical results on the cross section of the two-photon bremsstrahlung (2BrS) of a non-relativistic projectile scattered in a point Coulomb held. The effect of the radiation retardation is taken into account. The exact analytic evaluation of the point Coulomb two-photon non-dipoIe free-free matrix element, which characterizes the amplitude of the 2BrS process, is carried out following a method of momentum space integration developed by Gavrila. The obtained formulae are the generalization of the expressions derived earlier by several workers within the framework of the non-relativistic dipole approximation. Results of numerical calculations are compared with predictions of other theoretical approaches and with the experimental data on 2BrS.