X-ray optics research for free electron lasers: study of material damage under extreme fluxes

Free electron lasers operating in the 0.1–1.5 nm wavelength range have been proposed for the Stanford Linear Accelerator Center (USA) and DESY (Germany). The unprecedented brightness and associated fluence (up to 30 J cm−2) predicted for pulses <300 fs pose new challenges for optical components. A criterion for optical component design is required, implying an understanding of X-ray—material interactions at these extreme conditions. In our experimental effort, the extreme conditions are simulated by the currently available sources ranging from optical lasers, through X-ray lasers (XRLs) at 14.7 nm down to K-alpha sources (∼0.15 nm). In this paper, we present an overview of our research project on X-ray—matter interaction, including both computer modeling and preliminary results from optical laser experiments, the COMET tabletop high brightness ps XRL and a K-alpha experimental campaign carried out at the JanUSP laser facility at the Lawrence Livermore National Laboratory.