Gas Desorption Properties of Tungsten Coated Graphite Materials

Gas desorption properties of various tungsten-coated graphite materials used in a fusion reactor were investigated by using a technique of thermal desorption spectroscopy. Tungsten-coated graphite with a rhenium interlayer (W-Re/C) was prepared by chemical vapor deposition (CVD). Major outgassing species from graphite substrate were H2, H2O, CO and CO2. Various hydrocarbons such as CxHy (x=1-4) also desorbed at around 500 K. On the other hand, in the W-Re/C sample, the desorption amount of hydrocarbons was one order smaller than that of graphite substrate. However, a very large desorption of CO was observed at around 1200 K. For the W-Re/C material, the prebaking temperature required higher than 800°C.