| 摘要 |
A molecular suction pump for delivering a gas under conditions of molecular flow includes a pair of helically threaded parallel rotors (4, 7) which are mounted so that they can rotate in a stationary housing (1). The rotors (4, 7) have respective helical threads (3A, 3B) and respective helical grooves (2A, 2B) and are held in close mesh with one another. The helical threads (3A, 3B) are helically inclined in a direction with respect to the axes of the rotors (4, 7) and have a profile angle such that the helical threads (3A, 3B) are closely received in the respective helical grooves (2B, 2A) whilst maintaining the threads (3A, 3B) without contact with one another. The rotors (4, 7) rotate in a direction about their respective axes so as to displace a gas inserted through an inlet orifice (20) towards a discharge orifice (21) axially along the rotors (4, 7). <IMAGE>
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