Investigation of the laser-plasma interaction with the method of small- angle x-ray scattering (SAXS) at an XFEL

The combination of ultra-intense lasers with x-ray free-electron lasers (XFELs) opens up a variety of applications in plasma and shock physics. Many phenomena during the laser-target interaction happen on short time scales in the range from femto- to picoseconds and length scales of tens of nanometers to a few micrometers. Unlike the ultra-short, highly coherent x-ray pulse, optical methods or conventional continuous x-ray sources cannot probe the dynamics of the bulk material with sufficient temporal and spatial resolution. Here we will show the potential of SAXS in combination with short-pulse laser experiments. With this method it is possible to draw conclusions about the electron density distribution in the target by analyzing the XFEL diffraction pattern in the vicinity of the direct beam. A setup to perform such SAXS experiments was developed and optimized during a beamtime at the Matter in Extreme Conditions instrument (MEC) at the Linear Coherent Light Source (LCLS) in Stanford. We will discuss the setup and present a preliminary analysis of the data obtained during this experiment.