Calculation and design of a Ni-like Eu soft-x-ray laser

Numerical calculations of laser-irradiated ${\mathrm{EuF}}_2$ targets predict gain coefficients of 0.3–1.6 ${\mathrm{cm}}^{\mathrm{-}1}$ on several 4d-4p Ni-like Eu lines from 66 to 104.5 Å. Dielectronic recombination is important both in determining the ionization balance and in populating the J=1,2 4d excited states. Targets which are optimized for 0-1 gain show significantly less effect due to trapping on the 0-1 line than on the 2-1 line.