Frequency redistribution in the radiative transfer problem of amplifying media. Application to Ge22+ and C5+ x-ray lasers

This paper is devoted to the effect of frequency redistribution on x-ray la ser beams. The redistribution function, calculated by extending the frequen cy fluctuation model to two-photon processes, shows coherent scattering and a redistributed contribution. The spectral emissivity, corrected in order to account for this effect, is calculated for lasers using neon-like german ium and hydrogen-like carbon as amplifiers. The radiative transfer equation is solved, and the intensity of the x-ray laser output is given for two 3p -3s lines in a neon-like amplifier. We also study the variation in the emis sivity of the C5+ Balmer-alpha lasing line. The physical conditions of the calculation are derived from modelling of experiments conducted at the Ruth erford Appleton Laboratory.