Influence of orifice geometry on the simplification of transmission probability calculations

B. P. Butler, V. Music, F. J. Redgrave

Research output: Contribution to journalConference articlepeer-review

16 Citations (Scopus)


By careful design of the orifice employed in a dynamic-flow vacuum standard it is possible to ensure its mechanical stability while retaining a transmission probability very near unity. If spherical geometry is chosen the integral equation method calculations can be reduced to simple analytical expressions, and the introduction of approximations connected with evaluating integrals avoided completely. The analytical method provides direct traceability to dimensional data and achieves extremely low uncertainties. Details of the calculation for the orifice within an NPL system are presented.

Original languageEnglish
Pages (from-to)163-166
Number of pages4
Issue number1-2
Publication statusPublished - May 1999
Externally publishedYes
EventProceedings of the 1998 14th International Vaccum Congress 10th International Conference on Solid Surfaces 5th International Conference on Nanometre-Scale Science and Technology 10th International Conference on Quantitative Surface Analysis - Birmingham, GBR
Duration: 31 Aug 199804 Sep 1998


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