The interaction between neon and x-ray free-electron lasers with different laser parameters is systematically studied by solving a set of coupled rate equations. As an example, the evolution of 1s12s22p6 configuration is given under different incident photon numbers, pulse widths, and photon energies. We have also determined all of the charge-state populations as a function of three laser pulse parameters by averaging over time. The result shows that the variations of these charge-state populations demonstrate a pattern when the pulse width is shorter than 10 fs: some of the charge-states decrease rapidly, while the others rise but remain relatively constant for pulse width larger than 10 fs. The variation of the average charge with three parameters has also obtained. The average charge decreases for a pulse width shorter than 10 fs but remains basically unchanged for a pulse width longer than 10 fs.

No abstract