Researchers accelerate electrons to 1.2 GeV with laser

Researchers have cracked a long-standing barrier in plasma-based particle accelerators by using a “flying focus” laser to push electrons to more than twice the energy expected over the same distance. The team reports in Nature Physics that electrons reached 1.2 giga-electronvolts in just 20 centimetres of plasma, smashing the traditional dephasing limit that normally caps gains at around 0.5 GeV. The breakthrough was achieved at the University of Rochester’s Laboratory for Laser Energetics, where physicists designed a pulse that changes its focal point as it travels, keeping the accelerating force on target.

Plasma accelerators use intense laser pulses to carve waves in ionised gas, trapping and surfing electrons to ultra-high energies in centimetres rather than kilometres. The snag has always been dephasing: the electrons outpace the wave and lose their push. Earlier fixes—stronger lasers or denser plasmas—either melted optics or created unstable wakes. The flying focus solves this by stretching the laser into a curved chirp that refocuses continuously along the beam path, so the wave and electrons stay in lockstep.

Independent theorists say the Rochester setup matches simulations and call it a credible route to table-top colliders. Cost models suggest a flying-focus accelerator could deliver 1 TeV electrons in under 200 metres, versus tens of kilometres for today’s machines. The team is now scaling the laser power from terawatts to petawatts and testing novel plasma channels that could handle the extra punch.

If it scales, the technique could shrink the footprints of Higgs factories and linear colliders, cutting billions from future particle physics facilities. More immediately, compact accelerators would enable cheaper medical isotope production, ultra-fast X-ray probes for chemistry, and portable sources for cancer therapy.