Laser-plasma accelerator drives free-electron laser for record 8 hours

For the first time, researchers have demonstrated that a laser-plasma accelerator can reliably drive a free-electron laser for more than eight hours. The institutional report frames the development in practical terms and ties it to the broader mission or observing effort.

It is relevant because physics only takes a result seriously when the measurement chain remains robust under scrutiny. Experimental particle physics and precision metrology both operate in regimes where the signal sits far below the background noise, and where systematic uncertainties can mimic new physics if not controlled rigorously. The history of the field contains numerous anomalies that generated theoretical excitement before better data showed them to be artifacts, and it also contains genuine discoveries that were initially dismissed as noise. The difference is almost always resolved by independent replication with different instruments and different systematics. Published in Physical Review Accelerators and Beams, the result was achieved by a team led by Finn Kohrell at Lawrence Berkeley National Laboratory, in collaboration with. This article has been reviewed according to Science X's editorial process and policies.

This generates significant instability between laser shots, making it extremely difficult for users to sustain accurate results over long-term use. With these additions, the LPA was able to deliver an extremely stable succession of 100 MeV electron bunches for over 10 hours, at a rate of 1, 000 bunches per second.

This allowed for more than eight continuous hours of FEL operation at a wavelength of 420 nm, falling within the visible range. Based on the data they have gathered so far, Kohrell's team will now aim to refine their control systems even further.

Their next target is operating at 500 MeV, which would push the FEL output to between 20 and 30 nm, straddling the boundary between ultraviolet and X-rays on the electromagnetic. Altogether, their achievement opens up a new chapter in the development of next-generation light sources, and could help bring compact, affordable sources of coherent ultraviolet.

The broader interest lies as much in the method as in the headline number, because a durable measurement procedure can travel farther than a single result. When experimental physicists develop a technique that achieves new sensitivity or controls a previously uncharacterized systematic, that methodological contribution persists even if the specific measurement is later revised. This is one reason why precision physics experiments often generate long-term value that is not immediately visible in the original publication.

We rely on readers like you to keep independent science journalism alive. Kohrell et al, Over 8 hours of continuous operation of a free-electron laser driven by a laser-plasma accelerator, Physical Review Accelerators and Beams (2026).

Because the account originates with Phys. org Physics, it functions best as a primary institutional report that is close to the data and operations, not as independent scientific validation. Institutional communications are produced by organizations with legitimate interests in presenting their work in a favorable light, which does not make them unreliable but does make them partial. Details that complicate the narrative, including instrument limitations, unexpected failures and results below projections, tend to be minimized relative to progress messages. Technical documentation and peer-reviewed publications, where they exist, provide the complementary layer that institutional releases cannot substitute.

The next step is more measurement, tighter systematic control and scrutiny from groups whose experimental setups are genuinely independent. In experimental particle physics and precision metrology, the threshold for a discovery claim is a five-sigma excess surviving multiple analyses; an intriguing signal at lower significance is a reason to run more experiments, not a reason to revise the textbooks. Next-generation experiments currently under construction or commissioning will revisit several of the open questions that give the current result its context.

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