| 摘要 |
<p>To properly prevent backflow of particles into an upstream region of an inlet opening without involving significant fall in gas discharge performance. A chamfered face (28a) is formed on a rotary blade (28) of a turbo molecular pump by chamfering a corner portion formed by a surface (28b) facing the upstream direction of gas transferred from the inlet opening (5) to a discharge opening (6) and a surface (28c) facing the downstream direction of the gas. The chamfered face (28a) is formed in parallel with the axial direction of a shaft (7). In the turbo molecular pump (1), the region where the chamfered face (28a) of the rotary blade (28) is formed is determined based on the interval of adjacent rotary blades (28), moving speed of the rotary blade (28), and a region L with which particles are possible to collide and that is specified by moving speed etc. of the particles. In other words, the amount of cutting in the chamfering work of the corner portion formed by the face (28b) and the face (28c) of the rotary blade (28) is determined based on the region L with which the particles are possible to collide.</p> |
