Characteristic Investigation of the Silicon-Coated Films on TZM in EAST

Siliconization using 10%SiD₄+90%He assisted by ion cyclotron range of frequency discharge (ICRF) or glow discharge (GD) was performed to investigate the characteristics of silicon (Si) film on titanium-zirconium-molybdenum (TZM) wall in EAST. The experimental results indicated that the Si film coated with higher baking temperature was more compact and flat compared with that with lower baking temperature under the same working power. It was possibly due to the release of more physically adsorbed impurity gas from the surface with the high baking temperature. With the same baking temperature, the ICRF working power improved from 20 kW to 40 kW, the content of Si was increased, and the thickness of Si film was thicker about 1.5 nm. The higher working power was helpful in removing oxides and other impurities on the TZM sample, and also could increase the ionization and deposition of SiD₄. In addition, due to the higher working pressure and continuous working time, Si-coated film assisted by GD was thicker about 3.0 nm, compared with that assisted by ICRF. The above studies provide strong data support and experimental accumulation for EAST to evaluate the influence of silicon-coated film on TZM wall surface on plasma performance and its application in future fusion devices.