The influence of deuterium ions on the deuterium permeation and retention behavior in V-4Cr-4Ti alloy under plasma loading

Abstract

Deuterium (D) permeation and retention behavior in V-4Cr-4Ti alloy under ECR plasma or only gas loading has been studied. The gas pressure for plasma discharge was 0.6 Pa, which was the same as that for D2 gas loading. Different bias voltages of 0 V, -50 V and -100 V were applied to the samples to investigate the effect of ion incident energy on the D permeation behavior. D retention behavior was studied by thermal desorption spectroscopy (TDS). X-ray photoelectron spectroscopy (XPS) with depth profile was utilized to characterize the distribution of surface impurities and the chemical states of vanadium element. When the ion incident energy increases under plasma loading, D permeation flux decreases. D permeation fluxes under plasma loading are generally higher than those under only gas loading except those under D plasma loading with a bias of -100 V below 650 K. In addition, the total D retention in the plasma loaded sample is lower than that in the gas loaded one. XPS analyses show that the plasma loaded sample surface has a shallower V2O3 layer. Additionally, the percentage of VC in the plasma loaded sample is less than that in the gas loaded one. It suggests that D ions especially those with high ion incident energy could reduce the content of the oxides and carbides on the sample surface, which may finally result in the abnormal D permeation and retention behavior under or after plasma loading.