TY - CONF AU - Rauer, Patrick AU - Bahns, Immo TI - The Cavity based FEL project at the European XFEL M1 - PUBDB-2024-05549 PY - 2024 AB - We present the first commissioning results of the XFEL laser oscillator (XFELO) demonstrator project, a joint European XFEL and DESY effort. XFELOs promise unprecedented coherence, stability and Brilliance in the hard X-ray regime. Their successful realization would mean a leap forward for thefield of FELs, opening new experimental opportunities [1] and facilitating the notoriously demanding experiments at FEL facilities due to the increase in reproducibility. The demonstrator setup constructed at the European XFEL facility aims to realize the first ever true multi-bunch XFELO by achieving seeding with a bandwidth of 0.02eV at a fixed X-ray photon energy of 7 keV. Our demonstrator project shall showcase the capability to produce XFEL photon pulses with mJ-level pulse energies and high pulse-to-pulse stability. The scope of the project with its inherent challenges as well as its current status shall be presented in this contribution. T2 - 41st International Free Electron Laser Conference CY - 18 Aug 2024 - 23 Aug 2024, Warsaw (Poland) Y2 - 18 Aug 2024 - 23 Aug 2024 M2 - Warsaw, Poland LB - PUB:(DE-HGF)6 UR - https://bib-pubdb1.desy.de/record/613104 ER -