The dynamical behavior of x-ray emissions ranging from 90 to 110 Å generated from laser plasmas is studied and x-ray energies are measured for various target materials with the atomic number from 13 to 82. With the use of a picosecond YAG laser (YAG represents yttrium aluminum garnet), characteristic decay times can be obtained accurately and varied from 100 to 800 ps as functions of target materials. It is also found that the decay times are well correlated with x-ray energies as functions of the atomic number. From this correlation, the atomic-number dependence of decay times can be explained by considering that line x rays are emitted mainly through the radiative recombination processes. X-ray decay times can be measured correctly using a picosecond laser. The dynamical behavior of x-ray energies is explained by the computational result performed for aluminum as an example in the framework of a transient collisional radiative model.

• Received 16 December 1986

DOI:https://doi.org/10.1103/PhysRevA.35.4712