TAU Systems and Berkeley Lab demonstrate major advance in compact X-ray laser technology
Press Release
July 29, 2025
Austin, Texas

TAU Systems and Berkeley Lab demonstrate major advance in compact X-ray laser technology

  • TAU Systems and Berkeley Lab successfully demonstrated intense, coherent light pulses from a free-electron laser (FEL) driven by a laser-plasma accelerator (LPA)
  • Breakthrough brings compact X-ray free-electron lasers closer to real-world deployment in industries from semiconductors to quantum computing
  • The paper, published in Physical Review Letters, confirms that compact FELs, once a scientific aspiration, are now within practical reach


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  • Stephen Milton checking operation of the Hundred-Terawatt Undulator system
  • Sam Barber (Left) and Stephen Milton (Right) aligning the hundred terawatt laser
  • Reinier Van Mourik (Left) and Sam Barber (Right) reviewing FEL results

TAU Systems Inc, the leader in compact laser-plasma accelerators, together with researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (LBNL / Berkeley Lab), have achieved a major scientific breakthrough by successfully demonstrating intense, coherent light pulses from a free-electron laser (FEL) driven by a laser-plasma accelerator (LPA). This substantial milestone, published in Physical Review Letters, confirms that compact FELs, once a scientific aspiration, are now within practical reach.

“This is a major breakthrough,” said Dr. Bjorn Manuel Hegelich, CEO and Founder of TAU Systems. “These FEL results underscore our belief that laser-plasma accelerators represent a transformative shift in how we design and use particle accelerators, redefining their form, function, and massive potential for a wide range of industries from semiconductors to quantum computing”.

A new study, the result of a public-private partnership between Lawrence Berkeley National Laboratory and Texas company TAU Systems Inc., and published in Physical Review Letters, shows the way to smaller, less-expensive-to-build, and more numerous XFELs. The study co-authored by the joined team (LBNL: Sam Barber, Jeroen van Tilborg et al.) and (TAU: Stephen Milton, B. Manuel Hegelich et al.) demonstrates foundational technology on how XFELs might be scaled down significantly yet still deliver most of the remarkable seeing power of much larger machines.

Unlike traditional XFELs, which are typically kilometres long and cost billions to build and operate, compact laser-plasma accelerators can achieve equivalent electron energies within a footprint of just a few meters. The actual acceleration distance in the plasma structure is even shorter, only millimeters to centimeters. Conventional accelerators are limited to acceleration fields of about 50 megavolts per meter due to the damage threshold of the metal. With plasmas, however, more than 100 gigavolts (GeV) per meter are possible - over 2,000 times stronger, thus significantly shrinking the acceleration distance. Experiments by TAU Systems and scientists at The University of Texas at Austin have demonstrated 10 GeV electrons over a distance of only 10 cm and researchers at LBNL have independently shown 10 GeV over a 30 cm acceleration distance, using a different plasma structure.

“What that ultimately means,” said Hegelich, “is that you can generate the same high energy electron beams that a campus sized facility can with a compact machine that any university, lab, and most importantly a company can own and operate with just two people. This democratizes access and allows the development of all the fantastic scientific proof-of-principles shown at large facilities to be developed into relevant applications. With these new machines we can advance decades of publicly funded research from Technical Readiness Level 1-3 to TRLs of 6-9 and bring them to market for applications from medical theranostics to semiconductors and quantum computers and materials.”

“As part of this effort, we are applying our long-standing expertise in a type of advanced accelerator called laser plasma acceleration to shrink XFELs,” said Sam Barber, a staff scientist in the Accelerator Technology & Applied Physics (ATAP) Division at Berkeley Lab. “This is a big result,” Barber continues. “The fact that the 2-3 orders of magnitude FEL gain is so significant proves the LPA is producing the high-quality electron beams required to make FELs work. And the fact that it’s so reliable over tens of successive experimental campaigns speaks to the robustness of the LPA. In addition to stand-alone light sources, exceptionally high-quality electron beams from plasma accelerators could be injected into existing XFELs to significantly extend their performance.”

Shrinking XFELs, Amplifying Possibility

TAU Systems’ collaboration with Berkeley Lab focused on harnessing laser-driven acceleration to compress the physical size of FELs without compromising performance. By accelerating electron beams in a plasma wakefield, rather than via traditional radio-frequency cavities, the team achieved accelerating gradients up to 2,000 times stronger than conventional linear accelerators. The system demonstrated exponential FEL gain, producing coherent radiation with exceptional beam stability over multiple hours of operation.

“It’s not just about reaching very high electron beam energies with a compact laser-plasma accelerator system,” said Dr. Stephen Milton, Vice President of Accelerator Science at TAU Systems. “It’s about doing so reliably, with the beam quality needed for FEL lasing. That’s what our team has shown is possible.”

TAU played a critical role in this success, bringing deep expertise in accelerator beam physics, free-electron laser optimization and operation, and LPA system design. Through a Cooperative Research and Development Agreement (CRADA), TAU scientists worked alongside Berkeley Lab researchers to integrate the beamline, refine coupling optics, and stabilize the electron trajectories necessary for lasing.

Real-World Impact: From Biology to Quantum Manufacturing

Compact X-ray FELs have the potential to transform multiple industries. In the life sciences, they could bring atomic-resolution imaging of proteins and viruses to the lab bench. In semiconductors, they offer a path to next-generation lithography techniques capable of patterning quantum devices with ultra-fine feature sizes. In materials science, they can capture real-time structural changes at the nanoscale during fabrication and testing.

Applications include high-volume manufacturing of silicon quantum devices through soft X-ray-induced hydrogen desorption, stabilizing fleeting quantum states using ultrashort, coherent x-rays, and advancing the characterisation and development of quantum materials such as superconductors, quantum magnets, and topological insulators.

The team’s FEL system, implemented at Berkeley Lab’s BELLA Center, represents years of co-development between national lab researchers and TAU Systems. Key milestones included stable coupling through undulators, exponential FEL gain over multiple experimental runs, and consistent high beam quality, each marking progress toward the fully operational compact FEL.

TAU’s Vision: Compact Accelerators for Industry

Founded by pioneers in laser-plasma acceleration, TAU Systems is commercializing compact particle accelerators and specialized X-ray FELs that provide industrial users access to capabilities once confined to billion-dollar national labs. In 2023, TAU, alongside the University of Texas, set a world record by generating a 10 GeV electron beam in just 10 centimeters.

“Our mission is to make high-end accelerator science accessible to every sector that needs it, semiconductors, batteries, healthcare, science,” said Hegelich. “This latest breakthrough proves we’re on track to deliver powerful, compact machines that can sit on a lab bench and change entire industries.”

“TAU’s breakthrough is more than just a scientific milestone, it’s the start of a new industrial era,” said Lukasz Gadowski, founding investor in TAU Systems and chairman of the board. “Compact FELs will enable powerful new tools for a broad range of industries, from the next generation of semiconductors and quantum computing to bespoke medicines, and cancer treatments”.

Conventional FELs typically reach the so-called saturation regime, where the exponential increase in pulse energy plateaus. Operating an LPA-driven FEL in the saturation regime, and pushing the radiation wavelength into the X-ray regime, are major next steps for the LPA field.

This research was supported by the U.S. Department of Energy (DOE), Office of Science, the Office of Basic Energy Sciences, the Office of High Energy Physics, and through a CRADA with TAU Systems, and by the Gordon and Betty Moore Foundation.

About TAU Systems

TAU Systems is an Austin, Texas-based deep-tech company commercializing the first compact particle accelerators and specialized X-ray free-electron lasers that combine the capabilities of large accelerators with a small footprint to provide easy and affordable beam-time access for any company. Led by premier experts in laser-driven particle accelerators, TAU is democratizing access for the progress of semiconductors, batteries, medical imaging, nuclear energy, and more.

In 2023, TAU, together with the University of Texas, reached a world record with the successful demonstration of an electron beam with an energy of 10 billion electron volts (10 GeV) generated in 10 centimeters.

Learn more at www.tausystems.com

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