Determining the short laser pulse contrast based on X-Ray emission spectroscopy

The interaction of high-power short lasers with solid density targets is an important application of modern solid state lasers. However, uncertainties in measurements due to lack of information on the laser pedestal-to-peak contrast limits the validity of many conclusions. We show that X-ray spectral measurements can provide a straightforward way for accessing the laser pedestal-to-peak contrast. The experiments use silicon targets and relativistic laser intensities of 3 × 1020 W/cm2 with a pulse duration of 1 ps. By not using or using a plasma mirror we compare low and high contrast measurements of the Ly-α line and its satellites to show that these lines are an effective laser contrast diagnostic. This diagnostic has potential to reduce uncertainty in future laser-solid interaction studies.