| 摘要 |
PURPOSE:To enable a metallic wall to be baked without deteriorating the degree of vacuum, by setting, on the atmospheric side of the metallic wall, a chamber capable of undergoing vacuum exhaust during a period when the metallic wall is baked. CONSTITUTION:If a three-way valve 6 is set in a condition as shown in the figure during a step of baking, a preliminary exhaust chamber 5 is subjected to vacuum exhaust by means of a rotary pump 7. A gas introducing device consisting of a silver pipe 2 and a heater 3 is baked together with a vacuum container 1 in this condition. When introduction of gas is performed after attaining high vacuum, the three-way valve 6 is turned in the direction shown by an arrow so as to set the preliminary exhaust chamber 5 at the atmospheric pressure, then the heater 3 is heated by means of a DC power supply 4 so that the silver pipe 2 is set at a predetermined temperature before introducing oxygen gas. Any undesirable introduction of gas from a gas introducing metallic wall can be prevented from taking place during a backing process and any out-gas used to be generated out of an inner wall on account of insufficient effect of degassing treatment can be also reduced well.
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