Jianfei Hua

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.

When a laser beam hits a gas, it tears electrons from atoms and accelerates them to nearly the speed of light. As these electrons fly through the plasma, they emit X-rays, like a glowing trail from a fast particle. In the new work, physicists made a single laser pulse create not one but two such trails in succession.