Regensburg 2010 – wissenschaftliches Programm

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VA: Fachverband Vakuumphysik und Vakuumtechnik

VA 5: Vacuum measurement and instrumentation

VA 5.1: Vortrag

Montag, 22. März 2010, 14:40–15:00, H40

Vacuum measurement: state-of -the-art gauges and achievable accuracy — •Wolfgang Jitschin — Fachbereich MNI, Fachhochschule, 35390 Giessen

Modern vacuum gauges employ well approved functional principles: in the rough vacuum regime the piezoresistive or the capacitive sensor, in the fine vacuum regime the Pirani sensor and in the (ultra-) high vacuum regime both the hot and the cold cathode ionization tube. For the calibration of the gauges, primary standards such as the piston gauge and gas expansion apparatuses are available. Their accuraries can be estimated by careful analysis of errors and their propagation.

Regular recalibrations of the gauges provide information on their repeatability as well as on their stability with time. Frequently, the stability is a crucial issue for users of the gauges. Even in case of careful operation, statistical changes may originate from the influence of ambient conditions and systematic changes may be caused by aging effects. Comprehensive empirical data of the stability are now available. Modern state-of-the-art Pirani gauges are stable better than 1 %. Bayard-Alpert gauges are stable within a few percent after an initial period of running-in. Even some cold-cathode gauges are stable within 10 %. These data provide reliable information for judging the accuracy achievable in the usage of the gauges.