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We present a review of two methods used to model recent LCLS experimentalresults for the 3C/3D line intensity ratio of Fe XVII (Bernitt et al. 2012),the time-dependent collisional-radiative method and the density-matrixapproach. These are described and applied to a two-level atomic system excitedby an X-ray free electron laser. A range of pulse parameters is explored andthe effects on the predicted Fe XVII 3C and 3D line intensity ratio arecalculated. In order to investigate the behavior of the predicted lineintensity ratio, a particular pair of A-values for the 3C and 3D transitionswas chosen (2.22 $\times$ 10$^{13}$ s$^{-1}$ and 6.02 $\times$ 10$^{12}$s$^{-1}$ for the 3C and 3D, respectively), but our conclusions are independentof the precise values. We also reaffirm the conclusions from Oreshkina etal.(2014, 2015): the non-linear effects in the density matrix are important andthe reduction in the Fe XVII 3C/3D line intensity ratio is sensitive to thelaser pulse parameters, namely pulse duration, pulse intensity, and laserbandwidth. It is also shown that for both models the lowering of the 3C/3D lineintensity ratio below the expected time-independent oscillator strength ratiohas a significant contribution due to the emission from the plasma after thelaser pulse has left the plasma volume. Laser intensities above $\sim 1\times10^{12}$ W/cm$^{2}$ are required for a reduction in the 3C/3D line intensityratio below the expected time independent oscillator strength ratio.

Non-Equilibrium Modeling of the Fe XVII 3C/3D ratio for an Intense X-ray Free Electron Laser