Characterization of a transient Ni-like Ag X-ray laser under two-color irradiation

By frequency-doubling the long pre-forming pulse in the now well-known transient collisional excitation (TCE) scheme, a two-color (2ω/1ω) pumping of the nickel-like silver x-ray laser (XRL) has been investigated both experimentally and theoretically. The angular XRL characteristics have been studied and compared to standard (1ω/1ω) and inverse 2-color (1ω/2ω) irradiations. Through a statistical treatment of the recorded data, a significant reduction of the beam divergence has then been noticed. Moreover, the influence of the required traveling wave irradiation on the amplification duration has been checked, the observed shortening being explained by either a simple propagation model or more sophisticated simulations.