全超导托卡马克第一壁石墨材料的放气特性研究

Out-Gassing Characteristics of Graphite Used in Experimental Advanced Superconducting Tokamak

全超导托卡马克(EAST)实验中,面向等离子体材料(PFM)的放气特性直接影响到等离子体的品质。因此采用动态流导法的实验装置,在不同温度和真空度下对表面镀有SiC薄膜的GBST1308(B 1%、Si 2.5%T、i 7.5%、C 89%)掺杂石墨材料进行放气实验研究。测试分析了石墨材料在18℃至350℃经140h连续烘烤下的放气特性,并考虑温度对限流小孔流导的影响,计算出石墨材料的单位表面积放气速率和总放气量。通过四极质谱仪(QMS)监测和定性分析石墨材料放出气体的各种成分,利用标准谱图计算出残余气体中H2、H2O、CO和CO2的放气速率。结果表明,温度是影响石墨材料放气成分和放气速率的最主要因素,另外当石墨材料在350℃的高温18h恒温烘烤后能有效地减小杂质气体成分和放气速率。

A novel Instument has been successfully developed to evaluate the out-gassing characteristics of the SiC coated and composite materials doped GBST1308 graphite （B 1%, Si 2.5 %, Ti 7.5 % and C 89 % ）, which is used as the plasma facing material （PFM） in the experimental advanced superconducting tokamak （EAST）. During the continuous baking at 18℃ to 350℃ for 140 hours, the out gassing characteristics of the graphite, including the total out-gassing amount, and the out-gassing rate per unit area were measured, and then calculated. The desorbed H2, H2O, CO and CO2 gases were evaluated with the quadrupole mass spectroscopy （QMS） ; and their desorption rates were easily calculated by means of the standard spectrum library. The results show that baking temperature strongly affects both the type of desorbed gas and the out-gassing rote. We also found that baking at 350℃ for 18 hours significantly reduces the out-gassing rate and the partial pressures of various residual gases.