A proposed 100kHz repetition rate femtosecond laser plasma hard x-ray source at the Eli-Alps facility

Summary form only given. For a long time, high repetition-rate fs lasers were proposed as drivers for fs laser plasma x-ray sources, as a more affordable alternative to synchrotron and FEL light sources in the study of ultrafast molecular and atomic processes. Such applications have already been demonstrated^1,2. Lasers with a few mJ pulse energy, operating at 1kHz repetition rates require renewing laser target, for which liquid or gas targets are used, e.g. liquid Gallium³. The Attosecond Laser Pulsed Source (ALPS) is one of the four pillars of the Extreme Light Infrastructure (ELI) program of the European Union, to provide an attosecond duration EUV/XUV/x-ray light pulses for the scientific community. This facility is currently under construction in Szeged, Hungary. The high, 100kHz repetition rate laser system of the facility is envisioned provide 7fs, carrierenvelope-phase-stabilized 1mJ (later 5mJ) laser pulses, primarily intended for gas high harmonics generation. We propose to use this laser as a driver for an incoherent source of fs Kα x-rays in the 0.8-13keV energy range, with the possibility of reaching even higher photon energies. It is envisioned that this x-ray source would eventually be made available for outside user experiments. Technical constraints for the experiments are discussed regarding target materials, with emphasis on the issues of debris production at the unprecedented average powers. An electron transport model was developed to calculate hot-electron-to-Kα conversion efficiencies in the target. The model was used to evaluate and compare different target materials and target configurations, specifically, their projected x-ray conversion efficiencies at the expected laser parameters.