Theoretical analysis of deuterium retention in tungsten plasma-facing components induced by various traps via thermal desorption spectroscopy

Abstract

Thermal desorption spectra (TDSP) reported in the literature and resulting from thermal desorption experiments performed on tungsten samples exposed to deuterium at several fluences are analyzed using a reaction–diffusion model including up to ten different types of traps. The use of a large number of types of traps allows accurate fits of TDSP at all fluences using a unique broad spectrum of detrapping energy. Detrapping energies found in this work are in good agreement with detrapping energies predicted by density functional theory when several hydrogen atoms are trapped in a single tungsten vacancy. The comparison between the distribution of deuterium concentrations in material and distribution of trapped deuterium concentrations in TDSP suggests that traps characterized by a broad spectrum of detrapping energy, which may correspond to tungsten vacancies, are predominantly located near the material surface (≲10 nm).