Effect of coating morphology on the electron stimulated desorption from Ti–Zr–Hf–V nonevaporable-getter-coated stainless steel

The electron stimulated desorption (ESD) was studied for quaternary Ti–Zr–Hf–V alloy coated stainless steel samples with different surface structures: dense on one sample and columnar on another. The ESD yields were measured as a function of electron accumulated dose up to ∼1023 e−/m2 or greater and three different NEG coating activation temperatures: 150, 180 and 250 °C. After each ESD experiment the samples were saturated with a mixture of H2, CO and CO2. Both samples depicted lower ESD yields for all desorbed species compared to a ternary Ti–Zr–V alloy. It was also shown that although the columnar NEG coating demonstrated better pumping properties and, for NEG activated at 150 °C, lower initial ESD yields, the higher activation temperature may result in a significant H2 yield increase with dose for the columnar NEG coating. This effect was demonstrated for the first time and should be considered for application in particle accelerators.

► Electron stimulated desorption for Ti–Zr–Hf–V alloy coated stainless steel was studied. ► An effect of dense and columnar surface structure on ESD yields was compared. ► A significant H2 yield increase with dose for the columnar NEG coating was detected.