Regensburg 2002 – scientific programme

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VA: Vakuumphysik und Vakuumtechnik

VA 3: Vakuummesstechnik

VA 3.5: Talk

Monday, March 11, 2002, 16:30–16:50, H47

The recent results of research and development of primary vacuum standard based on piston-cylinder technique at CMI — •Jiri Tesar and Dominik Prazak — Czech Metrology Institute, Okruzni 31, 638 00 Brno, Czech Republic

In the last years new modifications of piston manometers (for utilisation as primary vacuum standards) appeared. There are classical piston manometers working under an evacuated bell, manometers with non-rotating piston and controlled gas flow in the gap and manometers with non-rotating piston with the conical gap.

Classical piston manometer in absolute pressure measurement design defines gauge pressure and separately measured pressure of residual vacuum is added to it. The value of this residual pressure under bell has influence on the dynamical parameters of the piston-cylinder. Evaluation of this influence is the first task of this paper.

The non-rotating piston manometer must be equipped with the control of the gas flow in its gap to assure good centring of the piston position. But the first centring by the installation of the instrument has also its influence. This is described in the second part.

In the case of the non-rotating piston manometer with the conical gap, the great care of the stabilisation of its output must be made. This is the topic of the third part.

In the end the reachable ranges and uncertainties for all three designs are listed.