Hydrogen isotope plasma-driven permeation through RAFM steel: isotope exchange and helium irradiation effect

Nuclear Fushion

article

Yue Xu¹  Kai Yang¹  Yun-Feng Xu¹  Lai-Ma Luo¹  Jun-Jie Ni⁴  Yu-Cheng Wu¹ 

[1] School of Materials Science and Engineering, Hefei University of Technology;National-Local Joint Engineering Research Center of Nonferrous Metals and Processing Technology;Copper Alloy and Forming Engineering Research Center of Ministry of Education;School of Materials Science and Engineering, Liaocheng University

关键词: plasma-driven permeation;    hydrogen isotope exchange;    RAFM steel;    isotopic effect;    helium plasma exposure;   

DOI  :  10.1088/1741-4326/aca91d

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Hydrogen isotope exchange in China low activation martensitic (CLAM) steel was investigated by plasma-driven permeation (PDP) measurements in the temperature range of ∼670–920 K. It was found that as H was introduced into D plasma, the permeation flux of HD increased while that of D₂ decreased. The total D permeation flux, however, remained almost unchanged. Such a result allowed the analysis of isotope replacement and showed that the reduction of D₂ is balanced by the rise of HD. In addition, the formation of HD was found to be closely related to the H and D content in plasma. Hydrogen isotopic effects on H and D plasma dissociation/ionization rate and on incident flux were evaluated by measuring plasma parameters including electron temperature and electron density using a triple Langmuir probe. The correlation between isotope effects on ionization rate in the plasma and isotope effects in the permeation flux was discussed. He plasma pre-irradiation and seeding during D PDP were also conducted to investigate the He effects on D diffusion. The total D permeation flux was found to be reduced by He seeding. Data analysis of Langmuir probe showed that ionization rate of D plasma was influenced by He seeding. Besides, under simultaneous D + He irradiation, He atoms were preferentially trapped at the defects resulting in a shallower D concentration gradient that described the observed decrease in D permeation rate. He plasma pre-irradiation was found to reduce D permeation flux with a much slower breakthrough to reach steady-state. The amount of D trapped at He-induced defects was derived quantitatively from the transient permeation curves. It is believed that He bubbles formed at the near surface act as trapping sites of D atoms, leading to a less effective diffusion coefficient and an enhanced retention in the material.

【 授权许可】

Unknown