An ultrashort electron beam developed at Stanford is the most powerful of its kind ever created—by a factor of five—offering new possibilities for recreating cosmic conditions in laboratory environments.
Scientists at Stanford‘s SLAC National Accelerator Laboratory created the beam using lasers to compress billions of electrons, a monumental achievement in particle accelerator and beam physics. The work has applications for quantum chemistry, astrophysics, and material science.
“Not only can we create such a powerful electron beam, but we’re also able to control the beam in ways that are customizable and on demand, which means we can probe a much wider range of physical and chemical phenomena than ever before,” said lead author Claudio Emma of the Department of Energy’s SLAC National Accelerator Laboratory.
Electron Beam Challenges
Previous electron beams have struggled to balance power with quality, a challenge the U.S. Department of Energy identified as a major hurdle in 2022. Traditional beams use a microwave field to compress and focus an electron beam, resulting in a staggered configuration where the rear electrons carry the most energy. However, as these electrons accelerate, they lose radiation and energy, diminishing the beam’s overall quality.
“We then send them around a bend, so the electrons in back catch up with electrons in front, and then at the end, you have a bunch of electrons together in a focused beam,” Emma said, likening the process to runners converging at the finish line of a race.
Controlling for Power
“The big advantage of using a laser is that we can apply an energy modulation that’s much more precise than what we can do with microwave fields,” Emma said.
The team’s innovation relies on a laser heater undulator, originally designed for X-ray free-electron lasers like SLAC’s Linac Coherent Light Source (LCLS). This undulator enables researchers to exert precise control over the beam by forcing billions of electrons into a micrometer-long line. Emma’s team spent months testing and fine-tuning the system. As a result, they can now generate well-controlled, high-energy, femtosecond-duration, petawatt-peak-power electron beams on demand.
“We have a one-kilometer-long machine, and the laser interacts with the beam in the first 10 meters, so you have to get the shaping exactly right, then you have to transport the beam for another kilometer without losing this modulation, and you have to compress it,” Emma added. “So it wasn’t easy.”
Putting the Beam to Work
The new beam will provide natural scientists with valuable applications in quantum physics, materials science, and astrophysics. One promising use involves replicating cosmic filaments observed in stars by interacting the beam with a solid or gas target in a laboratory setting. Such experiments could bring large-scale astrophysical phenomena into a controlled environment for in-depth study.
At SLAC’s Facility for Advanced Experimental Tests (FACET-II), researchers have already begun applying the beam in plasma wakefield technology research. Looking ahead, Emma envisions further compressing the beam to generate attosecond light pulses as the next stage of development.
Bluetooth Killer
“If you have the beam as a fast camera, then you also have a light pulse that’s very short, and now suddenly you have two complementary probes,” Emma explained. “That’s a unique capability and we can do a lot of things with that.”
“We have a really exciting and interesting facility at FACET-II where people can come and do their experiments,” he concluded. “If you need an extreme beam, we have the tool for you, and let’s work together.”
The paper “Experimental Generation of Extreme Electron Beams for Advanced Accelerator Applications” appeared on March 3, 2025 in Physical Review Letters.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.