Electron Beams Miniaturize X-Ray Lasers

Researchers’ simulations of ice-cold electron beams may open the door to shrinking X-ray free-electron lasers (X-FELs) to a small portion of their present dimensions.

X-FELs, also known as “engines of discovery,” transform the kinetic energy of an electron beam into strong photon bursts that extend down to hard X-ray wavelengths. For hot-dense matter research, resolving the structure of complex biomolecules for novel drugs, studying the properties of materials for next-generation microchips, and many other uses, X-FELs are employed.

A Plasma Wakefield Accelerator (PWFA), outfitted with a “Trojan horse” advanced electron injection technique called plasma photocathode, can generate electron beams 100,000 times brighter than the state-of-the-art, according to the study, demonstrating this with high-fidelity start-to-end simulations. The distribution with minimal momentum spread results in extremely cold electron beams.

In addition, the PWFA has an accelerating electric field capable of tens to hundreds of gigavolt-per-meters, which allows the accelerator to be realized on a centimeter scale instead of the kilometer scales of conventional accelerators. The research investigates the extraction, transportation, isolation, and injection of ultra-high brightness, ice-cold electron beams from plasma photocathode PWFA into an undulator without charge and quality loss; they do not “melt” or lose their coldness. When focused into an undulator, the ultrahigh-quality electron beam generates strong, coherent, laser-like photon pulses with pulse lengths in the attosecond (11018 of a second) range.

Read more

Related Content: Femtosecond Laser Pulses Using Time-Lens