Computational modelling of a Ne-like-Ar collisionally pumped OFI X-ray laser

Schemes in which a hot plasma is formed through optical field ionisation (OFI) of a noble gas lasing in the X-UV and pumped by collisional excitation have been proposed for some time [1]. However experimental evidence has been published only once [2] to date and only recently been reproduced [3]. We have performed detailed computational simulations for OFI produced neon like argon (Ar8+) which is predicted to lase at 46.9 nm on the [MATH] transition. Simulations of the atomic and hydrodynamic process within the plasma are used to calculate the temporal evolution of the gain and saturation intensities. A separate code is used to examine the propagation of the driving laser into the plasma and calculates the dispersion of the beam and the resulting degree of ionisation. We find that although high gains are predicted, the saturated output is relatively low at 107 – 108 W/cm2. Furthermore we find that propagating the driving laser into the gas is difficult due to severe diffraction effects and will be a limiting factor in the usefulness of such schemes