Studies on accelerated hydrogen isotopes permeation through plasma-facing components of fusion reactors

Experiments on deuterium (D) plasma-driven permeation through plasma-facing components (PFCs) mock-up have been performed in a linear plasma facility PREFACE. The effects of sample temperature, ion incident energy and surface conditions on the permeation behavior have been investigated. An 8 mm thick W armor tile with gaps is installed on membranes made by structural materials to simulate the monoblock type of PFC. CuCrZr alloy and CLF-1 steel membranes are tested at 500 K–750 K. Compared with gas-driven permeation cases, D permeation flux increases dramatically when the plasma is ignited, indicating that the energetic particles could pass through the gaps and result in enhanced permeation flux. The steady state D permeation flux increases with the increase of mock-up temperature, but the sample bias effects (i.e. incident energy effects) are not significant. PICS2 code calculations confirm the thickness of the sheath is comparable with the gap width under the plasma discharge conditions in PREFACE, suggesting that most of the incident ions into the gaps could not reach the bottom of the gaps.