THE SECOND SAUDI INTERNATIONAL CONFERENCE ON NUCLEAR POWER ENGINEERING (SCOPE-2)

The effects of helium ion (He+2) implantation into glassy carbon (GC) were systematically investigated. He+2 ions with an energy range of 17 keV were implanted into GC to fluences of 10¹⁶, 10¹⁷, and 10¹⁸ cm-² at room temperature (RT). The as-implanted GC samples were subsequently vacuum annealed at 300 °c, 500  °c, and 800  °c for 1 hour. The structural evolution of GC was characterized using Raman spectroscopy and transmission electron microscopy (TEM). A fluence-dependent trend in displacement per atom (dpa) and He concentration was observed. Raman spectroscopy revealed progressive structural disorder and amorphization at fluences of 10¹⁷ and 10¹⁸ cm-², marked by merging and redshifts of the D and G peaks, indicating tensile strain in the carbon matrix. Partial recovery of D/G peak separation and crystalline order was observed, especially at 800 °c for the 10¹⁶ cm-² fluence. TEM micrographs showed a confined damaged region of about 130 nm, with distinct defect aggregation towards the bulk for fluences of 10¹⁶ and 10¹⁷ cm-², whereas the defect aggregation appeared in two channels for the fluence of 10¹⁸ cm-². At a fluence of 10¹⁷ cm-², nonlinear dispersion and saturation effects were observed. Overall, annealing facilitated partial microstructural recovery, particularly for samples with fluences of 10¹⁶ and 10¹⁷ cm-² at 800 °c.