Regensburg 2016 – wissenschaftliches Programm

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VA: Fachverband Vakuumphysik und Vakuumtechnik

VA 2: Vacuum Physics

VA 2.1: Hauptvortrag

Montag, 7. März 2016, 10:30–11:15, H25

Novel routes in vacuum metrology at PTB and beyond — •Stephan Putzke and Karl Jousten — Physikalisch-Technische Bundesanstalt, Institut Berlin

At PTB, we have recently investigated and setup new standards for vacuum pressure calibrations which shall be detailed.

There are industrial processes which demand fast changes of vacuum pressure by several orders of magnitude in 1 second or less. Using a new standard at PTB, the response of fast pressure gauges can be characterized and calibrated from normal pressure down to the mbar range in a mere 20 ms. An overview over the needed complex gas-flow simulations will be given and compared to the experiment.

Simultaneously, a new standard for measurement of outgassing rates and generation of partial pressures in the high and ultrahigh vacuum regime has been setup which allows to prepare gas mixtures of up to three gases employing the continuous expansion method. This, for example, allowed us to compare in detail the performance of four different mass spectrometers (QMS) using the exact same prepared gas samples. Details such as total pressure and pumping effects will be discussed.

Our group is also concerned with (partial) pressure measurement using optical methods with which the typical problems of QMS can potentially be avoided. This includes effects like cross-sensitivity, pumping by the QMS, and total pressure effects. One such method is laser absorption spectroscopy using optical long-path cells. In a future project, we aim to access the total pressure in a system through the index of refraction, for which several concepts will be discussed.