Reviewed by Danielle Ellis, B.Sc.Sep 12 2024
In a study published in Nature Communications, scientists created a blueprint for creating ultrabright and ultrashort pulses of electron beams for the next generation of particle accelerator research.
Schematic of a plasma wakefield accelerator using optical laser beams and electron driver, escort, and witness beams for generating bright, coherent X-ray laser beams with attosecond duration and sub-Angstrom wavelength. Image Credit: University of Strathclyde
The study demonstrates how to generate "ice-cold" and ultrabright electron beams in a new form of accelerator known as a plasma wakefield accelerator (PWFA). The technique is based on a unique plasma idea in which the beams are initially created in the plasma and then carefully "escorted" out without loss of quality in a single plasma stage. This allows the PWFA-generated beams to emit intense X-ray pulses with exceptionally short durations and small wavelengths.
This might lead to the development of new scientific instruments like X-ray free-electron lasers (XFELs), which can observe stuff at smaller sizes and quicker speeds than are now achievable.
The Impact
The study demonstrates that electron beams of sufficient purity to generate hard X-ray FEL pulses may be created and maintained in carefully tuned PWFAs. The approach has the potential to tackle the challenge of retaining electron beam quality in plasmas.
This is a vital step toward using such motors as future light sources. It may also create new prospects for complementing tiny accelerators and high-energy physics research.
Summary
Research on novel complementary accelerator technologies and their uses in high-energy physics and photon science is ongoing. Thanks to a novel technique utilizing PWFAs, a team comprising scientists from the United States and the United Kingdom operating at the National Energy Research Scientific Computing Center (NERSC), a Department of Energy (DOE) Office of Science user facility, has made progress toward producing bright, high-quality electron beams.
The process creates an electron beam within a PWFA by using two lasers in a new type of plasma photocathode to tunnel ionization and then carefully removing the beam using beam-loading from an escort beam. Compared to conventional beams used in accelerators, the resultant beam can be orders of magnitude brighter.
The study shows how to create, remove, and isolate these incredibly brilliant beams in a beam transport line without sacrificing quality or charge. Such electron beams can subsequently generate intense sub-femtosecond hard X-ray pulses in undulators, similar to those generated at SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS), but at a far shorter wavelength.
This novel PWFA method may undergo testing at the DOE user facility, the Facility for Advanced Accelerator Experimental Tests (FACET-II), at SLAC. Tiny high-brightness beams from PWFAs could lead to more exotic studies like coherent photon-photon colliders and complementary tiny XFELs, according to experts.
Funding
DOE Office of Science, Basic Energy Sciences, the European Research Council, and the Science and Technology Facilities Council of the United Kingdom. The research used resources at the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science user facility, and the Shaheen Petrochemical Project of South Korea funded the study.
Journal Reference:
Habib, F, A., et al. (2024) Attosecond-Angstrom free-electron-laser towards the cold beam limit. Nature Communications. doi.org/10.1038/s41467-023-36592-z