The distribution of redeposited carbon atoms in tungsten film under ion irradiation

Abstract

The W films on stainless steel substrate were grown using magnetron sputter deposition. After the deposition films were irradiated under Ar ions with small amount of carbon. The XRD microstructure and phase composition of as-deposited W film demonstrated nanocrystalline microstructure with the mean size of crystallites equal to about 45 nm. After the characterization of W film properties the samples were moved into vacuum chamber and attached to the water cooled sample holder which was made of graphite. After irradiation of W film under Ar ions in described experimental conditions, three characteristic regions on the W film surface were distinguished: (i) the central region, where C readsorption rate exceeded plasma substrate erosion rate and continuous C film was grown with maximum thickness about 2 microns, (ii) the region of intensive plasma irradiation, where plasma substrate erosion rate exceeded C redeposition rate, and (iii) transfer region, where plasma erosion rate was about equal to C redeposition rate.