Deuterium retention in carbon-tungsten co-deposition layers prepared by RF magnetron sputtering

Abstract

The C-W co-deposition layer prepared by radio frequency magnetron sputtering was investigated to identify the characteristic of the C-W mixed layers in fusion experimental reactors. Layers were characterized by ion beam analysis (IBA), Raman spectra (RS) and scanning electron microscopy (SEM). It was found that D atoms in C-W layers are mainly trapped by the trapping site of C atoms, only a few of them are arrested by W atoms or defects. D concentration in the C-W layers deposited at 5.0Pa with a fixed flow rate ratio QD2/QAr=2.5 was lower than 10% and decreased slightly with increasing temperature. D concentration increased with the gas pressure from zero to 5 Pa and then decreased from 5 Pa to 10 Pa. RS revealed that the crystal structure of the C-W layers became graphite-like with increasing temperature. SEM images showed that the caves disappeared and convex bodies were dotted on the surfaces as the temperature increased.