Indexed by:Journal Papers

Date of Publication:2020-06-01

Journal:PLASMA PHYSICS AND CONTROLLED FUSION

Included Journals:SCIE

Volume:62

Issue:6

ISSN No.:0741-3335

Key Words:fusion-relevant; the evolution of He nano-bubbles in W; He ion flux

Abstract:Based on a He reaction rate model in W, we have analyzed the effect of fusion-relevant He+ flux on the evolution and surface bursting of He nano-bubbles in W. The concentrations of solute He atoms, trapped He atoms, and He nano-bubbles, and the radius of He nano-bubbles have been obtained as a function of depth, He+ dose, and He+ flux. He retentions in W are also calculated as the function of He+ dose and flux. Our modeling shows that the He+ flux varying from 5.0 x 10(18) to 5.0 x 10(24) m(-2)center dot s(-1) significantly affects the concentration of solute He atoms diffusing in W and trapped He atoms, the evolution of He nano-bubbles, and He retention in W. Both the concentration and radius of He nano-bubbles in W show the dependence on He+ flux, and their surface bursting leads to an increase ( Delta Ab-Burst<i) in the W surface area, thus the growth of W nano-fuzz. When He+ flux increases 5.0 x 10(18) to 5.0 x 10(24)m(-2)center dot s(-1), the bursting rate of He nano-bubbles is greatly reduced, accompanied by an increase in Delta Ab-Burst<i. However, Delta Ab-Burst<i is less dependent on the fusion-relevant He+ flux varying from 9.0 x 10(20) to 1.6 x 10(22)m(-2)center dot s(-1), which is consistent with the measured W nano-fuzz growth by He/D-2 plasmas.