Analysis of multiple-foil XRL targets using X-ray spectroscopy

Multiple-foil collisional excitation X-ray laser targets have been studied spectroscopically. Using spatially resolved 3d-2p X-ray spectra, the temperatures and densities obtained in single- and double-foil geometries have been compared. The ratio of the dipole transitions to the electric quadrupole transitions in the neonlike species has been used as a density diagnostic. An average-ion atomic physics model has been used to describe the ionization process, and a relativistic atomic physics code has been used for calculation of the level energies, populations, and gain calculations. The results confirm that the double-foils provide higher densities and in some cases concave density profiles. The extreme ultraviolet spectra in the range of 20-300 angstrom show the effect of target geometry and incident laser intensity on the laser lines and the ionization balance.