A fusion reactor is like a super-hot furnace where plasma reaches millions of degrees. The walls are made of tungsten, the most refractory metal there is. But even tungsten needs protection: fast particles from the plasma bombard the surface and knock atoms loose. These ejected atoms enter the plasma and cool it down, like a spoonful of cold milk in hot tea. To reduce contamination, a thin layer of boron is deposited on the walls — a technique called boronization.
Until now, it was unclear how exactly boron settles on tungsten and what happens under irradiation. The authors built a computer model that learns from precise quantum calculations. With it, they simulated millions of atoms and tracked each one. The model showed that boron forms a dense layer on the surface, not a thin smear. Moreover, the surface orientation determines how many atoms are knocked out upon impact.
This approach can speed up the search for better coatings for future reactors. Instead of expensive experiments, hundreds of options can be quickly tested on a computer. And one day, the walls of the fusion furnace will be as reliable as a cast-iron skillet.
Boron is not only used in reactors: it is a component of borosilicate glass, which blocks neutrons, and even appears in detergents.