TAU Systems and Lawrence Berkeley National Laboratory achieve breakthrough in laser-powered accelerator operation, enabling over eight hours of continuous free-electron laser output
- TAU Systems and Lawrence Berkeley National Laboratory ran a free-electron laser driven continuously by a laser-powered accelerator for over eight hours without any operator input
- Integrated multi-system laser and accelerator controls solved a longstanding engineering challenge
- Data from the run is already informing further performance gains, establishing TAU Systems as a leading compact light source developer
Eight Hours of Continuous Accelerator Operation: TAU & Berkeley Lab Reach New Milestone
TAU Systems, a pioneer in compact particle accelerator technology, announced a major scientific milestone: the first-ever demonstration of reliable, continuous operation of a laser-powered accelerator (LPA)-driven free-electron laser (FEL) sustained over more than eight hours without operator intervention. The achievement, published in a new research paper, marks a pivotal step toward making ultra-bright, tunable light sources practical for real-world scientific and industrial applications. The groundwork was laid in July 2025, when TAU Systems and Berkeley Lab demonstrated coherent, exponential FEL gain from a laser-plasma accelerator.
Traditional FEL facilities rely on large, costly radio-frequency accelerators that occupy entire campuses. LPAs shrink the acceleration distance from hundreds of meters to just millimeters by harnessing powerful laser pulses to accelerate electrons in a plasma. While the physics of LPA-driven FELs has been understood for almost 50 years, LPAs have historically had lower beam quality and stability, until now. Translating this technology into a stable light source has remained one of the field's most stubborn engineering challenges.
Engineering Stability in a Laser-Plasma Accelerator-Driven Free-Electron Laser
The TAU Systems team, in collaboration with Lawrence Berkeley National Laboratory (Berkeley Lab), achieved this breakthrough by engineering a suite of interlinking stabilisation technologies onto the Hundred Terawatt Undulator (HTU) experiment at Berkeley Lab’s BELLA Center. The result was 100 MeV electron beams delivered at 1 Hz with high consistency over a continuous ten-hour period, driving a self-amplified spontaneous emission (SASE) FEL operating at 420 nm (in the visible blue-ultraviolet range) for more than eight hours without any manual adjustments.
Stephen Milton, VP of Accelerator Science at TAU Systems said: “This is the moment the community has been working toward. We have shown that an LPA-driven FEL is not just a proof-of-concept experiment. It is a platform capable of delivering the stability that real scientific and industrial users demand.”
Improving LPA-Driven FEL performance: What the New Dataset Reveals
Beyond simply operating the light source autonomously, the team used the extensive dataset collected during the run to map correlations between the properties of the drive laser, plasma source, and electron beam, and the resulting FEL output. These insights are already informing the next phase of performance improvements, with residual correlations in the data indicating that further gains in stability and brightness are within reach.
The results, published in Physical Review Accelerators and Beams, confirm what TAU Systems has been developing over years. An overview of the underlying technology and further scientific literature including the latest research paper is available on the TAU Systems Technology page.
“This reported level of reliability and performance of the LPA-driven FEL not only represents a great improvement toward demonstrating the potential for future light source applications," says Finn Kohrell, a postdoctoral scholar in the BELLA Center at Berkeley Lab and lead author of the published results. "It also allows us to gather an unprecedented amount of data about the highly complex interaction between the LPA and FEL process, and to identify which parameters are most impactful for further improving the FEL performance."
Compact Light Source Applications: One Step Closer
The implications extend well beyond just one laboratory. Compact LPA-driven light sources have long been envisioned as a way to democratize access to high-brightness X-ray and UV beams, which are currently only available at a handful of national synchrotron and FEL facilities worldwide. Applications include structural biology, materials science, semiconductor lithography, medical imaging, and fundamental physics research. By demonstrating autonomous, multi-hour operation, TAU Systems and Berkeley Lab have cleared a critical barrier on the path to commercially deployable compact FELs.
TAU Systems characterizes the current system as a powerful research platform for the broader LPA-driven FEL community, enabling systematic studies of accelerator-to-light-source coupling that were previously impossible without long-duration stable operation. The company expects the findings to accelerate progress across the field and inform the design of future compact light source installations.
About TAU Systems
TAU Systems is an Austin, Texas-based deep-tech company commercializing the first compact particle accelerators and specialized LPA-driven 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, particle beam transport systems, and free-electron lasers, TAU is democratizing access for the progress of semiconductor manufacturing and radiation testing spacebound electronics.
Learn more at www.tausystems.com.
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