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Title: Electron-stimulated desorption from polished and vacuum fired 316LN stainless steel coated with Ti-Zr-Hf-V

In this study, two identical 316LN stainless steel tubular samples, which had previously been polished and vacuum-fired and then used for the electron-stimulated desorption (ESD) experiments, were coated with Ti-Zr-Hf-V with different morphologies: columnar and dense. ESD measurement results after nonevaporable getter (NEG) activation to 150, 180, 250, and 350 °C indicated that the values for the ESD yields are significantly (2–20 times) lower than the data from our previous study with similar coatings on nonvacuum-fired samples. Based on these results, the lowest pressure and best long-term performance in particle accelerators will be achieved with a vacuum-fired vacuum chamber coated with dense Ti-Zr-Hf-V coating activated at 180 °C. This is likely due to the following facts: after NEG activation, the hydrogen concentration inside the NEG was lower than in the bulk stainless steel substrate; the NEG coating created a barrier for gas diffusion from the sample bulk to vacuum; the dense NEG coating performed better as a barrier than the columnar NEG coating.
Authors:
; ; ;  [1]
  1. ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom)
Publication Date:
OSTI Identifier:
22320370
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 32; Journal Issue: 6; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACCELERATORS; COATINGS; DESORPTION; DIFFUSION; HAFNIUM COMPOUNDS; HYDROFLUORIC ACID; MORPHOLOGY; NITROGEN ADDITIONS; POLISHING; STAINLESS STEEL-316L; SUBSTRATES; TIN COMPOUNDS; VANADIUM COMPOUNDS; ZIRCONIUM COMPOUNDS