| 摘要 |
A low-temperature pump having a throttling valve formed by tilting radially disposed vanes (31, 32, 33, 34) in side-by-side relation, capable of fully opening a pump port to a process chamber. Motion from one vane can be coupled to the next through shims (21, 22, 23, 24) which support the vanes and form a seal when the vanes are flat in a common plane. One of the vanes may be controlled independently of the others so that coarse and fine modes of operation may be achieved by separately controlling (N-1) vanes and the Nth vane. The vanes are maintained in thermal contact with a chilled outer wall surface of a first pumping stage of a two-stage pump, the second stage coaxially surrounding a first stage maintained at a very low temperature. A central hub (45), at the convergence region for the vanes, supports a shield, protecting the second stage from radiation through a port in the upper regions of the pump |
