Helium retention depth profile in plasma-facing materials measured by glow-discharge optical emission spectroscopy

In order to quantitatively study the retention behaviors of helium (He) in the fusion relevant materials by Glow Discharge - Optical Emission Spectroscopy (GD-OES), tungsten (W) and copper (Cu) samples were implanted by He ions with different energies and fluences, and the He distributions in these samples were investigated by transmission electron microscopy (TEM) and simulated by the Stopping and Range of Ions in Matter (SRIM). After that these He implanted samples were used as calibration samples, and the electrical signal of GD-OES measurement was converted to He concentration depth profile. The results show that TEM investigations are consistent with SRIM simulation at the maximum concentration distribution depth of He. The experiment also found that He diffusion in the material is obvious, beyond the prediction range of SRIM simulation. After calibration, the He depth profiles in multi-energy implantation W, Cu and EUROFER97 samples measured by GDOES agree with the SRIM simulation. GD-OES and thermal desorption spectroscopy (TDS) independent experiments proved that the total retained He amounts in materials are close to the total implanted He amounts, indicating that using He-implanted standard samples combined with SRIM simulation to obtain GD-OES depth profile is reliable.

Automated summary

The diffusion of helium in materials was found to be beyond the prediction range of SRIM simulation. After calibration, the GD-OES measurements were in good agreement with the SRIM simulations. Overall, using helium-implanted standard samples combined with SRIM simulation was proven to be a reliable method to obtain GD-OES depth profiles.