الفهرس 
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Abstract
The concept for X-ray lasers goes back to the 1970s, when physicists realized that laser beams amplified with ions would have much higher energies than beams amplified using gases. X-rays are electromagnetic radiation of exactly the same nature as light but of very much shorter wavelength. XUV and X-rays differ from (IR), ultraviolet (UV) and visible light in their wavelength ranges. Which occupy the spectral region of electromagnetic spectrum between roughly 50 nm and 0.5 nm. The most familiar and suitable pumping mechanisms in soft X-ray lasers namely electron collisional pumping (ECP). Which population inversion can take place and it is maintained with time. The excitation of atom occurs directly or through atom or atom collision. The objective of this work to obtain the coherent radiation in XUV and X-ray. By using the fully relativistic atomic code (FAC) program based on Dirac equation, to calculate: The energy levels, transitions probability, oscillator strengths, and collision strength. Using this data to determine the reduced population for 69 fine structure. Level population can be calculated by solving the steadystate rate equation. The gain coefficient was calculated by using the Doppler broadening equation of several transitions in ArXIII, TiXVII, FeXXI, ZnXXV and SeXXIX. According to the calculations, we obtained a positive gain coefficient and this led to obtaining laser rays for the five elements.