TIME-RESOLVED MEASUREMENTS OF THE ANGULAR-DISTRIBUTION OF LASING AT 23.6 NM IN NE-LIKE GERMANIUM

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 7 almost-equal-to 22 mm length x 100-mu-m width with three line focussed beams of the SERC Rutherford Appleton Laboratory VULCAN laser at 1.06-mu-m 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.