Investigation of multi-keV silver x-ray sources at OMEGA

Abstract

We report on the results of experiments carried out at the OMEGA laser to address the performances of silver x-ray sources across several target and laser configurations. Every target consisted of a thin silver foil and a polystyrene shield mounted on the top of the foil in order to filter the x-ray emission in some spatial directions. Seven targets were fired with ∼4 to ∼7.7 kJ of 3ω energy and various incident powers, including pre-pulsed laser pulses. The radiant energies measured by the broadband spectrometer DMX were found to range in 350–710 J/sr and 80–120 J/sr for the 0–2 keV and >2 keV spectral bands, respectively. These experimental results are in good agreement with the predictions of 2D simulations performed with the radiation-hydrodynamics code TROLL. The radiant energies measured by the broadband spectrometer miniDMX in the >2 keV band range in 40–70 J/sr and give a measurement of the emission anisotropy of the sources. The TROLL simulated electron temperatures are within the error bars of the temperatures inferred from Thomson scattering during the laser pulses for most of the shots but deviate at later times when the laser is turned off.