A Study on Deuterium Retention Behavior of Plasma-Facing Materials for EAST
To investigate the deuterium (D) retention behavior of plasma-facing materials (PFMs) in the Experimental Advanced Superconducting Tokamak (EAST), SiC-coated graphite, bulk W, and W coating were exposed to D plasmas employing the material and plasma evaluation system in EAST. A comparative study was performed in an electron cyclotron resonance (ECR) linear plasma facility as well. For the EAST experiments, the local electron temperature and density were <inline-formula> <tex-math notation="LaTeX">$T_{e}\approx$ </tex-math></inline-formula> 10–15 eV and <inline-formula> <tex-math notation="LaTeX">$n_{e}\approx$ </tex-math></inline-formula> (1–3) <inline-formula> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> 10<sup>18</sup> m<sup>−3</sup>, respectively. In the ECR facility, the plasma parameters were measured to be <inline-formula> <tex-math notation="LaTeX">$T_{e} \approx 2.4$ </tex-math></inline-formula> eV and <inline-formula> <tex-math notation="LaTeX">$n_{e} \approx 1.5 \times 10^{17}$ </tex-math></inline-formula> m<sup>−3</sup>. The surface morphology was examined by scanning electron microscopy, and D retention properties of various PFMs were examined by thermal desorption spectroscopy. No significant modification of the surface morphology was observed after tokamak exposure experiments. Bulk W and W coating exhibit similar D retention behavior, while D inventory in SiC-coated graphite has been found to be much larger than that in W materials.