Influence of irradiation with low-energy helium ions on graphite and tungsten for fusion applications

Abstract

Plasma-facing components (PFCs) in fusion devices are exposed to an irradiation environment of high particle flux. Among various candidate materials for PFCs, graphite is used as a first-wall material of the Korea Superconducting Tokamak Advanced Research (KSTAR) and tungsten is being strongly considered as a divertor material of the international thermonuclear experimental reactor (ITER). In this experiment, graphite and tungsten targets were irradiated by using low-energy helium ions, and the irradiation's influence on each target was studied with particular emphasis on the surface change. Changes in the surface morphology were observed by using scanning electron microscopy (SEM); induced disorders in the structure were investigated by using X-ray diffraction (XRD), Raman spectroscopy, and electron spin resonance (ESR) measurements.