| 摘要 |
PURPOSE:To maintain the vacuum in a vacuum instrument at extremely high vacuum by covering a magnet exposed to the vacuum atmosphere in the vacuum instrument with a covering material. CONSTITUTION:An inner magnet 18 is fixed outside the inner yoke 17 is vacuum instrument, side plates 19, 20 are fitted to both ends of the inner yoke 17 and the inner magnet 18, a cylinder 21 is inserted outside the inner magnet 18, and the inner magnet 18 is cut off from the vacuum. Accordingly, the material adsorbed in holes of the inner magnet 18 is prevented from being discharged into the vacuum as gas, thus the extremely high vacuum can be maintained.
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