Plasma driven permeation of hydrogen through Nb: influence of the surface and bulk defects

Journal Article · Wed May 24 04:00:00 EDT 2006 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2213070· OSTI ID:20798718

Spitsyn, A; Skovoroda, A; Stolyarov, V; Pustovoit, Yu ^[1]; Petrov, V; Bykov, D; Voronkin, E ^[2]

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1. Nuclear Fusion Institute of RRC 'Kurchatov Institute', Moscow, 123182 (Russian Federation)
2. Moscow State Institute of Electronics and Mathematics, Moscow, 109028 (Russian Federation)

Plasma driven permeation of hydrogen through 25 {mu}m Nb foils was investigated under low-energy hydrogen ion irradiation in the range of membrane temperature 450-800 K and at different surface conditions. The interaction of hydrogen at molecular, atomic and ionizated states with niobium was under experimental research. The maximum value of low-temperature steady state permeation efficiency (SPE) was observed at Ar plasma cleaned inlet surface and with insignificant influence of outlet surface conditions. Such result is unusual and contradicts the developed classical representations and other published data for high-temperature range plasma-driven permeation. We explain this phenomenon by influence of defect structure of the polycrystalline membrane. The defects lead to the enhanced diffusion of hydrogen atoms along the crystallite sides. Such diffusion can essentially increase SPE of hydrogen through metal at low temperatures. The validity of this explanation was proved by the comparison of molecular hydrogen sorption and desorption measurements in poly- and mono-crystal Nb samples. The weighing method was used in that case. The phase transition {beta}'{yields}{alpha} in the Nb-H system is important for an explanation of SPE temperature dependencies in low-temperature range. The defects initiate phase transitions. The short-time enhanced hydrogen permeation was observed after irradiation of a membrane surface by Ar ions. The surface dissociation of the molecular ions, excited molecules and partially ordinary unexcited molecules of hydrogen can explain these observations.

• OSTI ID: 20798718
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 837; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ARGON IONS
COMPARATIVE EVALUATIONS
DESORPTION
DIFFUSION
HYDROGEN
HYDROGEN IONS
IRRADIATION
MEMBRANES
MOLECULAR IONS
MOLECULES
NIOBIUM
NIOBIUM HYDRIDES
PHASE TRANSFORMATIONS
PLASMA
POLYCRYSTALS
SOLAR PROTONS
STEADY-STATE CONDITIONS
SURFACES
TEMPERATURE DEPENDENCE
WALL EFFECTS