Effects of Helium Ions on Hydrogen Isotope Behavior in Tungsten

Influence of MeV helium implantation on deuterium retention in self-ion implanted tungsten

“…In a first step the thermal behavior of the implanted He is not released until 1200 K. This is confirmed by the measured TDS spectra, where no significant additional release of mass 3 above the HD level was observed: For the 1000 ppm specimen the release of 3 He was below about 2 % of the total implanted amount. For our implantation energy range it was reported by other authors before that up to 2000 K no He desorption was observed [8].…”

“…The damage level for the other He fluences used can be derived by scaling the 1000 ppm curve. The isotope 3 He was used for all implantations instead of 4 He due to the possibility to measure it quantitatively in tungsten by nuclear reaction analysis (NRA). Eleven different energies ranging from 500 keV to 1500 keV were applied in steps of 100 keV to achieve a relatively homogenous 3 He concentration which covers most of the W damaged zone as it is shown in Fig.…”

“…Because the lowest energy possible was 500 keV, the damage as well as the He concentration is reduced in the first 500 nm. The implanted He amount was measured ex-situ using the 3 He(d, p) 4 He nuclear reaction at a reaction angle of 135° using a PIPS-detector with 2000 µm depletion depth, a solid angle of 29.9 msr, and stopper foils of 5 µm Ni and 12 µm Mylar. The detected proton counts were converted to 3 He content by using the total cross section data from Möller et.…”

“…The implanted He amount was measured ex-situ using the 3 He(d, p) 4 He nuclear reaction at a reaction angle of 135° using a PIPS-detector with 2000 µm depletion depth, a solid angle of 29.9 msr, and stopper foils of 5 µm Ni and 12 µm Mylar. The detected proton counts were converted to 3 He content by using the total cross section data from Möller et. al [14] assuming angular independence in the center-of-mass system.…”

Molecular dynamics study of grain boundary diffusion of hydrogen in tungsten

“…However, recent measurements on polycrystalline tungsten using a secondary ion mass spectroscopy device (Cameca NanoSIMS 50L) with a lateral resolution of up to 50 nm at the Technical University of Munich indicate the possible enrichment of hydrogen along grain boundaries (see Figure 1). Similar enrichment of hydrogen along grain boundaries in tungsten has been suggested as a mechanism for grain ejection under hydrogen bombardment [13].…”