D retention and material defects probed using Raman microscopy in JET limiter samples and beryllium-based synthesized samples

TL;DR

This study uses Raman microscopy to detect beryllium deuteride in synthesized samples and analyzes defect signatures in JET limiter samples, aiding understanding of deuterium retention and material defects in fusion devices.

Contribution

It provides the first detection of amorphous BeD2 in synthesized samples and offers methods to distinguish its signature from other phenomena in Raman spectra.

Findings

BeD2 detected in synthesized samples containing 20% deuterium

No BeD2 signature found in JET limiter samples

Raman analysis of defects aids interpretation of deuterium retention

Abstract

We report on the detection by means of Raman spectroscopy of amorphous beryllium deuteride, BeD 2 , in magnetron sputtered deposits synthesized in two different laboratories and containing about 20 at.% of deuterium. In contrast, this signature has not been found for the JET limiter samples studied coming from the inner, outer or upper limiters, even when coming from a deposition zone of the limiters. We give a way to disentangle that BeD 2 signature from other signatures falling in the same spectroscopic range and mainly related to other phenomena. We also analyze the Raman characteristics of the JET sample defects. These results could help in the interpretation of D thermal desorption spectra and in future analyses of JET thick Be deposit divertor tiles.