Defects in tungsten responsible for molecular hydrogen isotope retention after exposure to low energy plasmas

Strongly Reduced Penetration of Atomic Deuterium in Radiation-Damaged Tungsten

“…This suggests that, upon their acceleration towards the surface by the bias potential, the ions directly penetrate the bulk, leading to high concentrations of deuterium and fast filling of the damaged layer. Our results are to some extent reminiscent of what has been observed by others on the diffusion of deuterium in tungsten containing considerable amounts of defects [26]. Also in these experiments the trapping of deuterium per unit time was the limiting factor for diffusion.…”

D2 gas-filled blisters on deuterium-bombarded tungsten

“…This clearly shows the D 2 gas filling of blisters, which was suggested decades ago [4,5] and which is supported by recent experiments, e.g., by D 2 bursts during TDS of implanted W or D 2 molecule observation in depth profiles of secondary ion mass spectrometry [10,11,18,19]. Such D 2 bursts were observed for many blisters of different sizes when they were individually opened by FIB.…”

“…In recent years blistering of tungsten (W) by hydrogen impact attracted new attention, leading to many publications in 2009-2010 [10][11][12][13][14][15][16][17][18][19][20][21][22]. Depending on bombardment conditions (ion energy, species distribution, fluence, flux, implantation temperature) and material grade (grain structure, microstructure, impurity content, specimen pre-treatment), different appearances of blisters and other surface protrusions were observed.…”

“…Such D 2 bursts were observed for many blisters of different sizes when they were individually opened by FIB. The value of the gas pressure inside the blister is strongly discussed [4,11,12,18]. By quantifying the D 2 content in the spike of an 5 individual blister with a calibrated QMS (not yet done) and measuring the blister volume by, e.g., CLSM, the gas pressure of at least large blister could be determined in the future.…”

“…Both assessments of the D 2 gas pressure in the blisters, i.e., FE calculations and Kirchhoff's plate theory [27], lead pressure to values framing the discussed range [4,11,12,18]. If the gas pressure is determined for a well-characterized individual blister, the mechanical properties of the W cap could probably be derived.…”