A High-Intensity Attosecond Light Source in Compact Geometry at the ELI ALPS User Facility

High-order harmonic generation has become a standard technique for producing attosecond extreme ultraviolet (XUV) pulses in the laboratory, yet the high flux necessary for nonlinear XUV photoionization remains accessible to only a few research groups. Here, we introduce the SYLOS Compact high-harmonic beamline at the Extreme Light Infrastructure Attosecond Light Pulse Source, specifically designed to provide the flux required for nonlinear optics in the XUV. We present a detailed characterization of the beam line demonstrating its capability to generate and utilize both intense attosecond pulse trains and isolated attosecond pulses. We further showcase the 2-XUV–photon double ionization of neon (Ne) and argon (Ar), achieved in a user campaign. The results underscore the beamline’s capability to support cutting-edge attosecond experiments and investigations of ultrafast electron dynamics on the attosecond scale.