For three days straight, a laser blasted a jet of gas, and every second it produced a beam of electrons with the energy of a tiny lightning bolt. Previously, such beams could only be produced in huge halls where the accelerator takes up an entire building. Now the whole setup fits in a room and ran without a glitch for 72 hours.

The secret is that the laser pulse pushes a wave through the gas, like a speedboat leaving a wake. Electrons ride this wave and are accelerated to near the speed of light. Over seven months at the factory, the system never failed: the beam remained stable, and the energy stayed at the same level to within one percent.

The beam was then directed at a metal target, turning it into X-rays. These X-rays shone through thick composite parts and revealed defects as small as a human hair — a hundredth of a millimeter. Previously, such cracks inside materials were only found after the part broke.

Now the factory can inspect every part before assembly. The laser accelerator is no longer a lab toy: it has become a working tool that sits on the shop floor and works every day.