Deuterium implantation in graphite and copper

Abstract

The D - D reaction has been used to depth profile deuterium implanted in graphite end copper over the temperature range 100 °K to 450 °K. The profiles are obtained using a method based on observing the energy spectrum of tritons emitted from D - D reactions initiated with a 200 KeV probing beam. Both graphite and copper, when implanted at 100 °K, are found to retain large concentrations of deuterium and the depth profiles show that the atomic loadings of deuterium (D:host atoms) in both materials are similar. However, the amount of deuterium retained within graphite is larger because of the greater number of host atoms per unit path. In graphite, the amount of deuterium retained continues to decrease with increasing temperature until at 425 °K the fetention has fallen to approximately half that at 100 °K. The profile shape is almost independent of target temperature and integrated dose. Copper targets show a greater decrease in the amount retained as the temperature is increased and a layer of deuterium is formed on the surface when the temperature is above 200 °K. Also, following prolonged bombardment at warm temperatures, the region in which the deuterium is retained begins to extend deeper into the target. The irradiated areas have been examined using a scanning electron microscope end blisters with diameters of approximately 1 to 10 microns have been seen in the copper targets but ho surface deformation has been observed on the graphite targets. The deuterium distributions within a copper target have also been measured using a 3He beam and a comparison is made between the two methods of profiling deuterium.