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 (O FI) of a noble ps lasing in the X-UV and pumped by collisional excitation h ave 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 lik e argon (Ar8+) which is predicted to lase at 46.9 nm on the 2p(5)3p S-1(0) --> 2p(5)3s P-1(1) transition. Simulations of the atomic and hydrodynamic p rocess within the plasma are used to calculate the temporal evolution of th e gain and saturation intensities. A separate code is used to examine the p ropagation of the driving laser into the plasma and calculates the dispersi on of the beam and the resulting degree of ionisation. We find that althoug h high gains are predicted, the saturated output is relatively low at 10(7) - 10(8) W/cm(2). Furthermore we find that propagating the driving laser in to the gas is difficult due to severe diffraction effects and will be it li miting factor in the usefulness of such schemes.