Observation of electron transport dynamics in high intensity laser interactions using multi-energy monochromatic x-ray imaging

We describe recent measurements in which a novel imaging technique was used to investigate the transport of high energy electrons produced by the interaction of a femtosecond laser pulse with a three-layer target at an intensity of 5 x 10(19) W cm(-2). The imaging system was configured to work in a singlephoton detection regime to identify the energy of the x-ray photons and to discriminate among K alpha photons generated in each target layer. Electrons emerging from the rear side after propagation through all the target layers were also detected using a custom developed detector. The results on fast electron propagation are combined with the information obtained from electron diagnostics and are modelled using analytical and numerical codes to obtain a detailed description of electron propagation dynamics.