New modeling of germanium soft-X-ray lasers using extended atomic data

Abstract

A collisional radiative model, explicitly including the interaction of the amplifying medium with the X-ray laser beam, is used to calculate the intensity of the 2–1 and 0–1 lines in neon-like germanium, as well as the population densities. The required energy levels and electron-impact collision strengths involve the configurations 1 s 22 s 22 p 6, 1 s 22 s 22 p 53 l, and 1 s 22 s2 p 63 l ( l= s, p, d). The fine-structure excitation rates coefficients are presented for temperatures in the range 100–700 eV. Well-known numerical codes are used for the atomic structure (SUPERSTRUCTURE) and electron–ion collisions (DISWAV/JAJOM). Finally, we solve the collisional radiative population equations. It is recommended to use excitation rates obtained from the extensive quantum calculations, rather than fit formulae. In this case, the calculated populations and intensities show substantial changes.