The properties of defects in tungsten containing hydrogen or helium atoms were investigated by model positron lifetime quantum-mechanical calculations. The electron wave functions were obtained in the local density approximation LDA to the density functional theory. On the bases of calculated results, the behaviour of vacancies, empty nano-voids and nano-voids with hydrogen and helium were discussed. It was established that hydrogen and helium in larger three-dimensional vacancy clusters in W change the annihilation characteristics dramatically. The hydrogen and helium atoms were trapped by lattice vacancies. These results provide physical insight for positron interactions in tungsten defects and could be used for prediction of hydrogen-H or helium-He4 and (tritium-H3) generation for the design of fusion reactors.

Model Calculation of Positron States in Tungsten Containing Hydrogen and Helium. T.Troev, E.Popov, N.Nankov, T.Yoshiie: Journal of Physics - Conference Series, 2010, 207[1], 012033