Thermodynamic effects in a gas modulated Invar-based dual Fabry-Pérot cavity refractometerShow others and affiliations
2022 (English)In: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 59, no 3, article id 035003Article in journal (Refereed) Published
Abstract [en]
By measuring the refractivity and the temperature of a gas, its pressure can be assessed from fundamental principles. The highest performing instruments are based on Fabry-Perot cavities (FPC). Gas modulation refractometry (GAMOR) is a methodology that has the ability to reduce the influence of disturbances to such an extent that high-precision (sub-parts-per-million) assessments of pressure can be made by the use of FPCs of Invar. To allow for high accuracy assessments, it is of importance to assess the uncertainty contribution from the thermodynamic effects that are associated with the gas filling and emptying of the cavity (pV-work). This paper presents a detailed scrutiny of the influence of the gas exchange process on the assessment of gas temperature on an Invar-based dual-FPC (DFPC) instrumentation. It is shown that by virtue of a combination of a number of carefully selected design entities (a small cavity volume with a bore radius of 3 mm, a spacer material with high heat capacitance, large thermal conductivity, and no regions that are connected with low thermal conductance, i.e. no heat islands, and a continuous assessment of temperature of the cavity spacer) the system is not significantly affected by pV-work. Simulations show that 10 s after the filling all temperature gradients in the system are well into the sub-mK range. Experiments support that refractivity assessments initiated after 40 s are not significantly affected by the pV-work. The analysis given in this work indicates that an upper limit for the influence of pV-work on the Invar-based DFPC system using 100 s long gas modulation cycles is 0.5 mK/100 kPa (or 1.8 ppm/100 kPa). Consequently, thermodynamic effects will not be a limiting factor when the Invar-based DFPC GAMOR system is used for assessments of pressure or as a primary pressure standard up to atmospheric pressures.
Place, publisher, year, edition, pages
IOP Publishing Ltd , 2022. Vol. 59, no 3, article id 035003
Keywords [en]
Gamor, Gas refractometry, Invar-based, Optical pressure standard, Pv-work, Quantumpascal, Atmospheric pressure, Cavity resonators, Fabry-Perot interferometers, Modulation, Refraction, Refractive index, Temperature, Thermal conductivity, Uncertainty analysis, Optical pressure, Pressure standards, Refractometry, Thermodynamic effect, Gases
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:ri:diva-59219DOI: 10.1088/1681-7575/ac5ef9Scopus ID: 2-s2.0-85128839678OAI: oai:DiVA.org:ri-59219DiVA, id: diva2:1667326
Note
Funding details: 2017-05013, 2018-04570, 2019-05029; Funding details: Horizon 2020 Framework Programme, H2020; Funding details: European Metrology Programme for Innovation and Research, EMPIR; Funding details: Vetenskapsrådet, VR, 621-2015-04374, 621-2020-05105; Funding details: Umeå Universitet; Funding details: Kempestiftelserna, 1823, U12; Funding text 1: This project (QuantumPascal, 18SIB04) has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme; Vetenskapsrådet (VR) (621-2015-04374 and 621-2020-05105); the Umeå University Industrial doctoral school; the Vinnova Metrology Programme (2017-05013, 2018-04570, and 2019-05029); the Kempe Foundations (1823.U12).
2022-06-102022-06-102024-05-27Bibliographically approved