Study on Energetic Ions Behavior in Plasma Facing Materials at Lower Temperature

An apparatus equipped with X-ray Photoelectron Spectroscopy (XPS) and Thermal Desorption Spectroscopy (TDS) was constructed to study interactions of energetic hydrogen isotopes with plasma facing materials. It is a remarkable feature of the apparatus that energetic ion implantation is carried out at around 150 K to study reactions of energetic ions with matrix by suppressing the reactions of thermalized ions. Using this apparatus, TDS experiments for pyrolytic graphite implanted with energetic D2+ ions at 173 and 373 K were carried out. The experimental results suggest that the deuterium implanted was released through a four-step release processes, involving three D2 and one CDx (x = 2, 3 and 4) desorption processes. Two deuterium and CDx desorption processes were observed in the temperature range from 700 to 1200 K. In addition, a new deuterium desorption process was observed for the deuterium-implanted sample at 173 K. This has never been observed for deuterium-implanted graphite implanted at temperatures higher than room temperature (R.T.).