Effect of Helium Ion Pre-implantation on Deuterium Retention Behavior in Tungsten

High-energy helium ion pre-implantation in tungsten and deuterium plasma exposure were carried out by high-energy ion implanter and linear experimental plasma system (LEPS). SEM-FIB, TEM, GD-OES and TDS measurements were used to analyze the effect of helium ion pre-implantation on deuterium retention in tungsten from both microstructure and deuterium concentration depth profile. The results show that a large number of helium bubbles form in the irradiated area by implantation of helium ions. After deuterium plasma exposure, the number of deuterium bubbles is significantly lower than that of sample with alone deuterium plasma exposure. GD-OES analysis shows that deuterium concentration depth profile increases obviously at the helium capture position, and the helium ion pre-implantation increases the diffusion depth of deuterium in tungsten. TDS analysis also shows that helium ion pre-implantation increases the retention of deuterium in tungsten. This can be attributed to the defects formed after helium ions pre-implantation provide a large number of new trap sites for deuterium capture in tungsten, which leads to the significant increase of deuterium retention in tungsten.