Doppler shift and frequency redistribution function in the laboratory frame. Effect on the output of neon-like germanium x-ray lasers

Abstract

This work is devoted to the effect of the Doppler shift and frequency redistribution on the output of soft-x-ray lasers operating in the collisional excitation scheme. Owing to the Doppler frequency detuning, the lineshape function as well as the redistribution function in the laboratory frame may differ from the same functions calculated in the atom frame. In fact, the lasing lines 0-1 (19.6 nm) and 2-1 (23.6 nm) in neon-like germanium show an important Doppler broadening and the redistribution functions calculated in the two frames differ by a large amount. The emissivity, corrected in order to account for frequency redistribution, is calculated, and the radiative transfer equation is solved. We show that the intensities of the above lines depend on the frame chosen.