Prof Peter Norreys FInstP;

Abstract:

The time varying ratio of intensities of resonance lines of H- and He-like ions in laser irradiated cylindrical fibre targets is analysed using a hydro/atomic physics code. Correspondence between the ratio and gain on the Balmer α transition of H-like ions in the adiabatically cooling and recombining plasma is found. The line ratios and absorbed energies corresponding to maximum gains for carbon, oxygen and fluorine plasmas are calculated. A useful diagnostic method is proposed for infering the absorbed energies in the plasmas and for monitoring the production of plasmas which should give maximum gain during adiabatic expansion. © 1993.

Abstract:

The time dependence of the angular distribution of soft X-ray lasing at 23.6 nm in Ne-like germanium has been measured using a streak camera. Slabs of germanium have been irradiated over ≈ 22 mm length × 100 μm width with three line focussed beams of the SERC Rutherford Appleton Laboratory VULCAN laser at 1.06 μm wavelength. The laser beam sweeps in time towards the target surface plane and the divergence broadens with time. The change of the peak intensity pointing and the broadening of the profile with time are consistent with expectations of the time dependence of refraction and divergence due to density gradients in the plasma. © 1992.