X-ray spectra from glass microsphere laser targets

A study was made of the continuous and line x-ray spectra obtained in the course of spherical high-power pulse irradiation of glass microsphere targets using a multibeam neodymium laser apparatus. The continuous spectrum, measured in the quantum energy range 1–16 keV, was characterized by two values of the effective electron temperature: 0.6 keV (for the thermal electrons) and 2 keV (for the fast electrons). Two-dimensional images of the laser target, obtained using the x-ray lines due to transitions in H- and He-like silicon ions, were compared with the results of target image calculations made employing a one-dimensional gasdynamic program "Zarya". The possibility was investigated of determining the electron density and temperature profiles in the corona of SiO₂ microsphere targets and a study was made of the influence of the transient nature of the plasma ionization state on the x-ray line emission from multiply charged Si ions.