A series of high capacity turbomolecular pumps with pumping speed up to 40 m 3 s −1

Abstract

Highly reliable turbomolecular pumps with pumping speed of 5−20 m 3 s −1 (He) are described and their parameters presented. The pumps are made using a dual flow principle. The ultimate pressure is about 5 × 10 −8 Pa; the compression ratio is (0.6−2.1) × 10 4 (H 2) and (0.9−3.2) × 10 5 (He); the main component of residual gases is hydrogen. Dynamic and molecular seals are used to protect the pumped cavity against penetration of oil coming from the bearing units. Oil is pumped through the bearings. The pump design envisages different positioning of its inlet flange (at an angle of 45 °). The pumps are resistant to sudden atmospheric air cycles. They remain workable at a pressure of 5 × 10 −2 Pa for a time and can be operated during 5–10 h under a pressure of about 1 × 10 −1 Pa. A design of the high-vacuum oil-free turbomolecular pump with an active electromagnetic bearing is described. The calculated pumping speed of the pump is 40 m 3 s −1 and the compression ratio is 1 × 10 4 (H 2).