Model of the Zero Drift of a Bellows Vacuum Gauge with an LC Oscillator and the Anomaly of the Axial Thermal Expansion of the Bellows

Abstract

We have derived an equation of thermal perturbations by deduction from a physical model for deformation vacuum gauges with bellows as the elastic element. The model can be used to analyze the temperature zero drift of micropressure gauges, to divide the zero drift into components with regard to particular effects, and to eliminate or to diminish those effects. A zero drift of 0.1 Pa/K was obtained for a micropressure gauge rated at up to 1000 Pa (0.01 %/K). We have found that the temperature zero drift occurs mainly because with rising temperature the bellows expands to an anomalously large extent (1.5 to 2 times) along its axis as compared to the expansion of the alloy used to make the bellows.