K-Shell Spectroscopy of Au Plasma Generated with a Short Pulse Laser

The production of x-rays from electron transitions into K-shell vacancies (K-Alpha/Beta emission) is a well known process in atomic physics and has been extensively studied as a plasma diagnostic in low and mid Z materials. Such spectra from near neutral high-Z ions are very complex and therefore difficult to describe with analytical models. In this experiment a Au plasma emission spectrum was measured with a transparent cylindrically bent quartz crystal. The Titan laser system at Lawrence Livermore National Laboratory was used to deliver a 350 joule, 10 ps, laser pulse to the Au target. K-Alpha(1,2) and K-Beta(1,2,3) transitions were observed over a range of target sizes. Additionally, a series of shots was conducted with a backside pre-ionizing long pulse. FLYCHK, an atomic NLTE code designed to provide ionization and population distributions, will be used to diagnose the plasma temperature, density and ionization states. This information will ultimately be used to gain insight into how the plasma conditions affect the production of positrons.