SPACE-RESOLVED AND TIME-RESOLVED ION DISTRIBUTION IN A RECOMBINING ALUMINUM X-RAY LASER-PLASMA

These experiments map out the ionization balance present in a recombin ation x-ray laser plasma as a function of time and space. The plasma i s created by irradiating an Al strip target with a 600-ps Nd:glass las er, and is probed by an x-ray backlight at several times as it cools a nd recombines. The primary diagnostic is an x-ray spectrometer which s patially resolves the He-like to Be-like K alpha absorption spectra as a function of distance from the target surface. The experimental resu lts indicate that the plasma ions important to the lasing are observed much farther from the target than expected from simulations. These re sults are consistent with x-ray gain measurements, and demonstrate the effect of non-local thermal equilibrium cooling on the ionization bal ance.