A tabletop device has sparked a fusion reaction using boron plasma for the first time – and it was thousands of times more effective than attempts using solid targets. Although the method is still a way off from producing clean energy on a commercial scale, the device can double as an astrophysical lab, recreating the conditions needed to make elements in cosmic-ray crashes.
Mainstream fusion power schemes fuse hydrogen isotopes called deuterium and tritium to make helium nuclei, releasing large amounts of energy in the process. However, the reaction also produces high-energy neutrons, which would damage whatever vessel the fusion reactor is in and render anything around them radioactive.
The problem goes away with boron-based fusion, in which protons are fired at a boron target to create helium nuclei but no neutrons. Better still, boron is a lot more common on Earth than deuterium or tritium. The downside is that much more initial energy is needed to get the reactions going.
In 2005, scientists in Russia experimented with firing lasers at a solid boron target. They reported generating thousands of helium nuclei, but that is not nearly enough to make the reaction self-sustaining. Now Christine Labaune at the École Polytechnique in Palaiseau, France, and colleagues have used a high-energy infrared laser to first turn boron isotopes into a hot, charged gas, or plasma.