| Popis: |
A vacuum chamber made from TiN coated titanium and a vacuum chamber made from electropolished stainless steel were pumped down with the bakeout process at temperatures of 150 °C, 200 °C, 250 °C and 300 °C. The time (t) dependence of the total pressure (P) at each bakeout temperature was described as P = A · t−0.2 for the electropolished stainless steel chamber, and P = A′ · t−1.0 for the TiN coated titanium chamber. The residual gases in the test chambers were also measured in the bakeout process. During the bakeout process, the rate of hydrogen outgassing remained steady while other residual gases decreased continuously. The rate of hydrogen outgassing in the stainless steel chamber was more than 10 times greater than in the titanium chamber at a bakeout process of 250 °C. The reason the pressure in the titanium chamber decreased more rapidly than in the stainless steel chamber during the bakeout process can be explained by the difference in the rate of hydrogen outgassing. Using a turbomolecular pump, a lower pressure was obtained in the titanium chamber than in the stainless steel chamber after cooling down the chamber from a 193 h baking at 250 °C to room temperature. |
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