Simulations of photopumped x-ray lasers

This thesis presents results of the simulations of H-like K / He-like K - H-like Cl and H-like Al - Li-like Fe photopumped X-ray laser schemes and of the relativistic spectral profiles formed within the plasma. Its goal is to investigate effects of the pumping radiation and laser-produced plasma conditions on gain. Plasma expansion was simulated in planar geometry using the 1-D Lagrangian code MEDIOS. To calculate the pumping radiation, or modal photon density, we wrote a separate post-processor that calculates the transfer of radiation through a plasma in 3-dimensional geometry at different times and takes into account gradients of all plasma characteristics. Gain was calculated using the code GALAXY. Results were encouraging enough to plan experiments. To investigate the effect of electric micro-fields on spectral lines we incorporated the theory of the relativistic Stark profiles. To calculate relativistic transition rates, oscillator strengths and lifetimes in H-like ions we wrote the code HITR. We also wrote codes HISP and HEZ to calculate Stark profiles. Mixing of all relativistic levels was taken into account. Particular calculations were centred on the H-like Cl lasing plasma. We found that the effect of electric micro-fields leads to the increase of the spectral line width in comparison to the Doppler width. This results in the decrease of overlap between the pumped and pumping radiation profiles that can significantly decrease gain. Results obtained in our work verifies the importance of the quantum relativistic effects on the spectral profiles and, therefore. X-ray lasing gain. (author)Available from British Library Document Supply Centre-DSC:D213673 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo