Unexpected energy barrier for uptake of hydrogen in tungsten wall of fusion reactor

The reactor walls of future fusion reactors will absorb fusion fuel one million times slower than previous research had indicated. A layer of bound hydrogen on the surface of the tungsten wall seems to protect the deeper metal layers. An international team led by FOM PhD researcher Rianne 't Hoen has published this finding in Physical Review Letters. 't Hoen did her research using the plasma generator Pilot-PSI of FOM Institute DIFFER.

In a fusion reactor, heavy isotopes of hydrogen (deuterium and tritium) fuse into helium. As a result of this clean energy in the form of heat is released. The exhaust of a fusion reactor must be able to withstand large quantities of heat and particles. Nevertheless the reactor walls always absorb some of the fusion fuel. As for safety reasons only a limited quantity of fuel may be present in the reactor, physicists are trying to minimise the amount of hydrogen absorbed by the wall material. Therefore the advanced future reactor ITER will be fitted with an exhaust made from the metal tungsten. Tungsten has a high melting point, is a good conductor of heat and absorbs little hydrogen, although this absorption can rise by several orders of magnitude under the influence of neutrons from the fusion reaction.