Nanowire-zapping lasers unlock micro-scale nuclear fusion efficiency record
Researchers at Colorado State University (CSU) have broken the efficiency record for nuclear fusion on the micro-scale. Using an ultra-fast, high-powered tabletop laser, the team's results were about 500 times more efficient than previous experiments. The key to that success is the target material: instead of a flat piece of polymer, the researchers blasted arrays of nanowires to create incredibly hot, dense plasmas.
We have nuclear fusion to thank for our very existence – without it, the Sun wouldn't have fired up in the first place. Inside that inferno, hydrogen atoms are crushed and through a series of chain reactions, eventually form helium. In the process, tremendous amounts of energy are released. Theoretically, if we can harness that phenomenon we could produce an essentially unlimited supply of clean energy, and although breakthroughs have been made in recent years, nuclear fusion energy remains tantalizingly out of reach.
But the process could have other applications as well, which could be unlocked by getting it to work on a smaller scale. Rather than the huge laser setups used by other researchers to recreate the conditions at the center of stars, the CSU team used a relatively compact laser that could fit on a tabletop to beam ultra-fast pulses of light at the target.
In other experiments, that target is usually a flat piece of a material, but in this case, the researchers used arrays of nanowires made of deuterated polyethylene. The laser blasts destroy the nanowires in a matter of femtoseconds (quadrillionths of a second), creating ultra-high density plasmas, which in turn give off helium and a huge amount of neutrons.
The scientists report that their experiment produced up to 2 million fusion neutrons per joule of laser energy. That's about 500 times more than other experiments have produced using flat targets, and sets a new record yield for lasers of this intensity.
Along with improving our understanding of the mysterious interactions between light and matter, more efficient fusion neutron production could help advance neutron imaging techniques. These neutral subatomic particles are proving useful for peering inside objects in a similar way to X-rays, but they cause no damage to the target and can penetrate metals and other materials that X-rays can't.
The research was published in the journal Nature Communications.
Source: Colorado State University