Femtosecond hard X-ray plasma sources with a kilohertz repetition rate

Laser-driven plasma sources of femtosecond hard X-ray pulses have found widespread application in ultrafast X-ray diffraction. The recent development of plasma sources working at kilohertz repetition rates has allowed for diffraction experiments with strongly improved sensitivity, now revealing subtle fully reversible changes of the geometry of crystal lattices. We provide a brief review of this development and present a novel plasma source with an optimized mechanical and optical design, providing a high flux of several 10¹⁰ photons/s at the Cu-Kα energy of 8.04 keV and a pulse duration of ≤300 fs. First experiments, including the generation of Debye–Scherrer diffraction patterns from Si powder, demonstrate the high performance of this source.