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    Vacuum Science & Technology Tuesday Sessions
       Session VST-TuM

Paper VST-TuM4
Power Optimisation of a Hybrid Turbomolecular-drag Vacuum Pump

Tuesday, October 30, 2001, 9:20 am, Room 125

Session: Turbomolecular, Molecular Drag and Similar Pumps
Presenter: S. Giors, Varian Vacuum Technologies, Italy
Authors: S. Giors, Varian Vacuum Technologies, Italy
R. Cerruti, Varian Vacuum Technologies, Italy
J.C. Helmer, Varian Vacuum Technologies, Italy
Correspondent: Click to Email
Varian has specialised in the development of Gaede stages for extending the tolerable fore pressure of hybrid turbomolecular-drag vacuum pumps. The design of the first hybrid turbomolecular pumps was focused to the optimisation of their vacuum performances, disregarding the power dissipated to get them. The power dissipated by the pump was just a consequence of a given vacuum optimisation, normally resulting in high power dissipation rates. Nowadays, this approach is no more acceptable, as a consequence of our need to build pumps able to reach higher and higher fore pressures. Today the optimisation has to be carried out, taking into account both power dissipation and performance, stage by stage. In a previous paper@footnote 1@ we presented a model able to predict power consumption of a single Gaede stage. Now that model is extended to a cascade of Gaede stages and applied to the optimisation of a full commercial pump. The drag stages of a 250 L/s pump have been redesigned according to that model in order to heavily reduce its power consumption without compromising its vacuum performance and without affecting the production process. Measurements show about 50% in power reduction with respect to the old pump without any loss in pumping speed, compression ratio or high throughput characteristics. This work demonstrates that further improvement is possible in the design of commercial hybrid turbomolecular-drag pumps, in order to reduce power dissipation, and hence cooling requirements, rotor working temperature and reliability. @FootnoteText@ @footnote 1@ R. Cerruti, M. Spagnol, J. C. Helmer, "Power dissipation in turbomolecular pumps at high pressure", J. Vac. Sci. Technol. A 17(5), 3096-3102, Sept/Oct 1999.