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Free-electron lasers create coherent light by constantly accelerating a beam of electrons. Free-electron lasers are particularly useful because they can produce radiation with a short-wavelength, down to just a few tenths of a nanometre. Thus, it is hoped they will become an important tool for atom-level material characterization.
Intense, short-pulse laser irradiation generates energetic electrons that heat targets to extreme conditions relevant to laser fusion. Here, authors used an X-ray Free Electron Laser to perform spatiotemporal measurements in solid-density copper foil with sub-micron and femtosecond resolutions.
A waveguide can increase the coupling between an electron beam and electromagnetic field in a THz Free Electron Laser. The authors characterize the spectral properties of a compact waveguide FEL including dual-frequency lasing and tunable wavelength.
The authors combine differentiable physics modelling and neural networks to extract high-resolution electronic density of states of warm dense materials from resonant inelastic x-ray scattering spectra. With this approach, they identify distinctive features in the valence structures of warm dense Fe and Fe2O3, also estimating their temperature and M-shell binding energies.
This Review examines the principles of operation and progress made in developing free-electron lasers that feature plasma-wakefield-acceleration technology.
Warm dense copper, created by an X-ray free-electron laser, features a transition from reverse saturable absorption to saturable absorption. The results can be used to benchmark non-equilibrium models of electronic structure in warm dense matter.
A bright, ultrashort X-ray pulse is used to transiently create and characterize warm dense copper. As the pulse intensity is increased, the opacity of copper is strongly altered. The recorded X-ray absorption spectra, substantiated by a theoretical electronic structure model, provide insight into the non-equilibrium electron dynamics during the formation of warm dense matter.
Global proliferation of free-electron laser X-ray sources has improved accessibility. Now the race is on for high repetition rates, attosecond pulses, and full coherence.
Following first lasing at LCLS-II — a coherent X-ray laser source driven by a 700-m superconducting linear accelerator — several upgrades are already in the works. Nature Photonics spoke to LCLS director Mike Dunne about LCLS-II commissioning hurdles as well as future plans.
The demonstration of a low-loss diamond mirror cavity that can temporally store X-ray pulses brings hope for a future generation of X-ray free electron lasers.
Exacerbated by the impacts of climate change and the recent energy crisis, concentrated efforts towards more sustainable research have become matters of urgency, in particular for large-scale accelerator complexes and light sources.