Hydrogen incorporation into metal deposits forming from tungsten or stainless steel by sputtering under mixed hydrogen and argon plasma at elevated temperature

Basic considerations on the pump-down time in the dwell phase of a pulsed fusion DEMO

“…As best guess, we see a concentration range between 10 2 and 10 4 (mol H)/m 3 as found in measurements of combined magnetron sputtering and ion implantation coatings and in plasma induced W deposits [10][11][12]. Analysis of samples from the AUG tungsten divertor material showed an inventory of 2.5 × 10 3 (mol H)/m 3 [13].…”

Carbon and Hydrogen Accumulation on Exhaust Duct in LHD

“…In the present work, in order to understand carbon and hydrogen accumulation behavior in the exhaust duct of the fusion experimental devices, stainless steel (SS316) substrates were mounted in the exhaust duct of LHD, in which graphite material is used in divertor region and SS316 is used in first wall, during the 13th experimental campaign. It has been reported by the present authors that metal deposit formed from stainless steel by hydrogen plasma sputtering can retained a large amount of hydrogen during deposition process [10]. In order to confirm whether hydrogen isotopes co-deposited with metals remain in the deposit for a long time under high vacuum condition of LHD exhaust duct, metal deposit were preliminarily formed on some of SS316 substrates by hydrogen plasma sputtering of a stainless steel plate.…”

Hydrogen gas driven permeation through tungsten deposition layer formed by hydrogen plasma sputtering

“…In order to estimate tritium inventory in the vessel, it is necessary to evaluate a generation rate of deposition layers and tritium concentration in the layer. The present authors have investigated hydrogen or deuterium retention in W deposition layers growing under hydrogen isotope plasma exposure [1] and reported that hydrogen isotope concentration in W deposition layer depends on temperature and a ratio of hydrogen flux and tungsten flux to the growing surface of the layer [2]. Since hydrogen retention capacity of W deposition layer is several orders of magnitude larger than that of W bulk, the presence of W deposition layer on plasma-facing wall may affect fuel recycling and inventory.…”