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Pumping speed measurement of turbomolecular pumps by a quasistationary pump‐down method
Author(s) -
Jitschin W.
Publication year - 1999
Publication title -
vakuum in forschung und praxis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.213
H-Index - 13
eISSN - 1522-2454
pISSN - 0947-076X
DOI - 10.1002/vipr.19990110306
Subject(s) - throughput , body orifice , volume (thermodynamics) , mechanics , dome (geology) , pressure measurement , flow (mathematics) , materials science , acoustics , mechanical engineering , computer science , physics , thermodynamics , engineering , geology , telecommunications , paleontology , wireless
The pumping speed of a turbomolecular pump is usually measured by injecting a stationary known gas flow via a standardised test dome into the pump and measuring the equilibrium pressure in the test dome. The ratio of gas throughput and pressure is just the pumping speed. In practice, the pressure can be conveniently and accurately measured, whereas the convenient and accurate throughput measurement is a challenging experimental problem. The present paper reports on a new method for measuring the pumping speed in which the throughput is generated by the pumping down of a vessel via an orifice. From the decrease of vessel pressure with time, and from known vessel volume, the throughput can be directly and accurately derived. Exploring measurements by the new method in fact give high accuracy, systematical error sources are practically negligible.