Spectroscopic study of energetic helium-ion irradiation effects on nuclear graphite tiles

• Energetic helium-ion irradiation on nuclear graphite tiles studied for plasma facing components.
• XPS reveals recrystallization at low dose irradiation and DLC sites at higher doses.
• Raman spectroscopy reveals increasing diamond-like defects and structural deformation.
• Average inter-defect distance obtained as a function of irradiation dose from Raman intensities.

Helium ion-irradiation effects on the nuclear graphite tiles were studied in order to understand the structural modifications and damages that can be produced by fusion reaction in tokamaks. The surface morphological changes due to increasing dose of the irradiation were examined by the field-effect scanning electron microscopy, and X-ray photoelectron spectroscopy elucidated the changes in the shallow surface bonding configurations caused by the energetic irradiation. Raman spectroscopy revealed the structural defects and diamond-like carbon sites that increased with increasing irradiation dose, and the average inter-defect distance was found from the Raman peak intensities as a function of the irradiation dose.