Secondary source developments at PHELIX - From diagnostics to applications

We report on the results of the first experiment on electron acceleration in the self-modulated laser-wakefield acceleration regime conducted at PHELIX. PHELIX is ideally suited for this type acceleration scheme, offering high pulse energies, intermediate (picosecond) pulse duration and a excellent laser beam-quality control, which is crucial for the acceleration process and quality of the electron beam. This experimental campaign 
included the successful commissioning of an F/17 long-focal-length configuration at the PHELIX petawatt target area, as well as the deployment of a gas jet and comprehensive electron beam diagnostics. These efforts mark the first step towards establishing this type of laser-driven x-ray backlighter for high-energy density (HED) experiments at PHELIX and potentially at a future laser system to be integrated into the APPA cave at FAIR. Such a source would enable studies on heavy-ion beam driven states of matter using laser-driven x-ray diagnostics. Such a source also offers promising capabilities for studying plasma states relevant to Inertial Fusion Energy (IFE) or further application in medical research. These research fields require sources with high photon numbers on short time 
scales, small source sizes, a low divergence and, depending on the type of application and diagnostic, a broadband spectrum of the x-ray and gamma beam.