Short wavelength laser calculations for electron pumping in Be I and B I isoelectronic sequences (18≤Z≤36)

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Abstract
Level populations of the 2s3p and 2s23p configurations in ions of the Be I and B I isoelectronic sequences can be inverted, with respect to populations of the 2s3s and 2s23s configurations, by electron collisional pumping. In the case of B I ions, the process is analogous to the process for Ne‐like ions, which has lately received considerable attention. In the case of Be I ions, the inversion is a consequence of the slow radiative decay of the 2s3p 3P2 and 2s3p 3P0 levels. Level populations are calculated for Be‐ and B‐like ions with atomic number Z between 18 and 36. For each sequence, 20 levels are involved with principal quantum number n equal either to two or three. Using the level populations, gain coefficients are calculated for transitions of the type 2s3s−2s3p and 2s23s−2s23p. Finally, the opacity of the 2s2p−2s3s and 2s22p−2s23s transitions are discussed, for plasma parameters for which a reasonable gain can be achieved.