A group of scientists from the University of Wisconsin in Madison found an opportunity to reduce the size of the working areas of thermonuclear reactors. The researchers tested a special coating for the interior walls of the reactor chambers that not only dissipates heat better but also binds neutral hydrogen atoms in the plasma; this is a source of diminishing power of the plasma cable and a means of stopping the reaction prematurely.

“These neutral hydrogen particles cause power losses in the plasma, making it very difficult to maintain a hot plasma and create an efficient small fusion reactor.” – explains the leader of the group, Mykola Yalovega, a researcher in nuclear engineering and engineering physics at the University of Wisconsin at Madison (UW-Madison).

To solve the aforementioned problem, the Yalovega team cold-sprayed the interior walls of the reactor zone with tantalum as a refractory coating. Particles of this refractory metal were sprayed and formed into pancakes on the surface of the stainless steel. This type of application did not create a continuous layer of metal, but left contour boundaries of each drop. It was these boundary regions that bound neutral hydrogen very easily if its atoms flew out of the plasma cord.

Moreover, the tantalum sprayed wall surface that improved its weld did not need to be thrown away or recycled, but had to be replaced with a new product. Heating the renovated section to extremely high temperatures released the trapped hydrogen and the chamber design element was once again ready for reactor operation. It is clear that such a decision would make the repair of thermonuclear reactors much easier and cheaper. Finally, technologically simple spraying will make it possible to repair the inner walls of the reactor zone at home.

“The creation of a refractory metal composite with properties such as erosion resistance and overall flexibility of the material through well-controlled use of hydrogen is a breakthrough in the development of plasma devices and fusion power systems.” – said Oliver Schmitz, the second author of the article. “The possibility of modifying the alloy and incorporating other refractory metals to develop composite materials for nuclear applications is of particular interest.”

The researchers tested their development at the university’s WHAM (Wisconsin HTS Axisymmetric Mirror) facility. The installation is also a testing ground for the design of a thermonuclear power plant, in which the company Realta Fusion, founded by university graduates, is involved.