Photon emission by ions interacting with short intense laser pulses: beyond the dipole approximation

Photon emission by light hydrogen-like ions interacting with intense, few-c ycle Ti:sapphire laser pulses is calculated within the strong-field approxi mation of Lewenstein and co-workers, modified so as to treat the coupling o f the atom with the incident field beyond the dipole approximation. The app roach is tested by comparing with results obtained by solving the time-depe ndent Schrodinger equation numerically for a two-dimensional model ion. The effect of the magnetic field component of the driving pulse is significant beyond 2 x 10(17) W cm(-2) peak intensity. It leads, in particular, to a s aturation in photon emission with increasing laser intensity. As compared w ith emission polarized along the same direction as the incident field, emis sion polarized along its propagation direction is weaker by about two order s of magnitude at the maximum peak intensity considered, 3.6 x 10(17) W cm( -2).