Laser-Heated Nanowires produce Micro-scale Nuclear Fusion

This is the target chamber (front) and ultra-high intensity laser (back) used in the micro-scale fusion experiment at Colorado State University. Credit: Advanced Beam Laboratory/Colorado State University

Record-setting efficiency for generation of neutrons. Nuclear fusion, the process that powers our sun, happens when nuclear reactions between light elements produce heavier ones. It’s also happening – at a smaller scale – in a Colorado State University laboratory. Using a compact but powerful laser to heat arrays of ordered nanowires, CSU scientists and collaborators have demonstrated micro-scale nuclear fusion in the lab. They have achieved record-setting efficiency for the generation of neutrons – chargeless sub-atomic particles resulting from the fusion process.

Laser-driven controlled fusion experiments are typically done at multi-hundred-million-dollar lasers housed in stadium-sized buildings. Such experiments are usually geared toward harnessing fusion for clean energy applications. In contrast, Rocca’s team of students, research scientists and collaborators, work with an ultra fast, high-powered tabletop laser they built from scratch. They use their fast, pulsed laser to irradiate a target of invisible wires and instantly create extremely hot, dense plasmas – with conditions approaching those inside the sun. These plasmas drive fusion reactions, giving off helium and flashes of energetic neutrons.

In their Nature Communications experiment, the team produced a record number of neutrons per unit of laser energy – about 500X better than experiments that use conventional flat targets from the same material. Their laser’s target was an array of nanowires made out of a material called deuterated polyethylene. The material is similar to the widely used polyethylene plastic, but its common hydrogen atoms are substituted by deuterium, a heavier kind of hydrogen atom.

The efforts were supported by intensive computer simulations conducted at the University of Dusseldorf (Germany), and at CSU. Making fusion neutrons efficiently, at a small scale, could lead to advances in neutron-based imaging, and 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. https://engr.source.colostate.edu/in-csu-lab-laser-heated-nanowires-produce-micro-scale-nuclear-fusion-with-record-efficiency/