Measurements of silver K-shell and bremsstrahlung emission from thin-foil laser targets as a function of laser prepulse energy are presented. The silver targets were chosen as a potential 22 keV backlighter source for the National Ignition Facility Experiments. The targets were irradiated by the Titan laser with an intensity of 8 × 1017 W/cm2 with 40 ps pulse length. A secondary nanosecond timescale laser pulse with controlled, variable energy was used to emulate the laser prepulse. Results show a decrease in both Kα and bremsstrahlung yield with increasing artificial prepulse. Radiation hydrodynamic modeling of the prepulse interaction determined that the preplasma and intact target fraction were different in the three prepulse energies investigated. Interaction of the short pulse laser with the resulting preplasma and target was then modeled using a particle-in-cell code PSC which explained the experimental results. The relevance of this work to future Advanced Radiographic Capability laser x-ray backlighter sources is discussed.

Measurements of K alpha radiation yield and x-ray bremsstrahlung emission from thin-foil silver targets are presented. The targets were irradiated by a short pulse laser with intensities from 5 X 10(16) to 10(18) W/cm(2) at 40 ps. Single hit charge-coupled device detectors, differential filter-stack detectors, and a crystal spectrometer were used to investigate the angular distribution of the K alpha and bremsstrahlung x-rays. This study is the first to use a broadband detector to estimate the absolute numbers of K alpha photons and to determine K alpha to bremsstrahlung ratios. The relevance of this work in the context of x-ray diffraction and x-ray radiography is discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3473822]