Researchers have taken a key step towards furthering nuclear fusion applications.
Scientists from Colorado State University are using a compact but powerful laser to heat arrays of ordered nanowires, demonstrating micro-scale nuclear fusion in the lab with record-setting efficiency for the generation of neutrons resulting from the fusion process.
The research team used an ultra-fast, high-powered tabletop laser that they built from scratch.
The fast, pulsed laser was used to irradiate a target of invisible wires and instantly create extremely hot, dense plasmas with conditions approaching those inside the sun. The plasmas drive fusion reactions, giving off helium and flashes of energetic neutrons.
The new laser’s target was an array of nanowires made from deuterated polyethylene, a heavier kind of hydrogen atom that is similar to the widely used polyethylene plastic but with its common hydrogen atoms substituted by deuterium.
“We demonstrate a dense fusion environment created by irradiating arrays of deuterated nanostructures with joule-level pulses from a compact ultrafast laser,” the study states. “The irradiation of ordered deuterated polyethylene nanowires arrays with femtosecond pulses of relativistic intensity creates ultra-high energy density plasmas in which deuterons [D] are accelerated up to MeV energies, efficiently driving D–D fusion reactions and ultrafast neutron bursts.”
The researchers measured up to 2 × 106 fusion neutrons per joule, an increase of about 500 times with respect to flat solid targets, a record yield for joule-level lasers.
If scientists are able to make fusion neutrons efficiently at a small-scale, they could pave the way for advances in neutron-based imaging. It could also result in neutron probes to gain insight on the structure and properties of materials. The results also contribute to understanding interactions of ultra-intense laser light with matter.
Nuclear fusion, the process that powers the Sun, occurs when nuclear reactions between light elements produce heavier ones. Laser-driven controlled fusion experiments are generally done with lasers costing upwards of $100 million and housed in stadium-sized buildings. The experiments are usually geared toward harnessing fusion for clean energy applications.
Intensive computer simulations conducted at the University of Dusseldorf (Germany), and at CSU supported the efforts.
The study was published in Nature Communications.