Characteristics of turbomolecular pumps


          

刊名：Vakuum in Forschung und Praxis.
作者：Gerhard Voss
刊号：534E0001
ISSN：0947-076X
出版年：2002
年卷期：2002, vol.14, no.4
页码：228-233
总页数：6
分类号：TB7
语种：eng
文摘：Graphs of "high-vacuum pressure as a function of backing pressure" ("p{sub}(HV) versus p{sub}(VV)") and "compression as a function of backing pressure" ("K versus p{sub}(VV)") are presented in this article. The performance of any turbomolecular pump can be fully and reliably evaluated with the aid of these graphs. Until now these graphs have only seldom been shown in catalogs. The catalogs generally lack the so-called "limit lines" ("Q as a function of p{sub}(VV, Kmax)") For a prescribed gas throughput Q, the limit line indicates what minimum pressure must be generated by the backing pump at the fore-line port of the turbomolecular pump so that a stable pressure exists at the high-vacuum side of the turbomolecular pump. Using the gas-type-specific limit line and the corresponding, usually well-documented pumping-speed curve, one can already describe the functional proficiency and performance of a selected combination of turbomolecular pump plus backing pump in an approximate manner - but not yet completely. In this article we also indicate analytical functions which excellently describe the pressure dependence of the compression and pumping speed.



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