| 摘要 |
PROBLEM TO BE SOLVED: To provide a pressure reducing device which is inexpensive, has a high evacuation speed and can prevent particles from being whirled up. SOLUTION: The pressure reducing device having an evacuation mechanism for reducing the pressure in a vacuum chamber comprises a main evacuation passage having one end communicating with the vacuum chamber and the other end communicating with a vacuum pump, a first on-off valve provided in the main evacuation passage, a slow evacuation passage having one end communicating with the vacuum chamber via the main evacuation passage or directly and the other end communicating with the vacuum pump via the main evacuation passage or directly, a filter made of a circular tube shaped silica porous body and a second on-off valve provided in the slow evacuation passage. COPYRIGHT: (C)2009,JPO&INPIT
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