Simulation of pressure-induced cavity deformation – the 18SIB04 Quantumpascal EMPIR project

Abstract

The 18SIB04 QuantumPascal EMPIR project aims for development of photon-based standards that can replace primary standards of the SI unit of pressure, the Pascal. In this project, four partners simulated the pressure-induced deformation of a given Fabry-Pérot cavity, using various versions of two types of software, COMSOL Multiphysics (R) and ANSYS Workbench. It was demonstrated that, for a given geometry and set of material parameters, simulations of the deformation could be performed by the various partners with such small discrepancies that methodological mistakes of the simulation procedures will solely contribute to a sub-ppm uncertainty in the assessments of refractivity of N<sub>2</sub>.

Uncertainty in mechanical deformation of a Fabry-Perot cavity due to pressure: towards best mechanical configuration

“…In [1] the results of simulating the deformation of the Fabry-Perot cavity are shown, and they are collected in Table 4. The result simulated in Solid Edge software by the CEM is less than 10 -3 time bigger than the average of [1].…”

“…In [1] the results of simulating the deformation of the Fabry-Perot cavity are shown, and they are collected in Table 4. The result simulated in Solid Edge software by the CEM is less than 10 -3 time bigger than the average of [1]. The uncertainty in CEM's simulation was calculated as a rectangular distribution centred in -6.3846 × 10 -12 Pa -1 and with a width equal to two times the difference of CEM's value and the average value of [1] (2.24 × 10 -14 Pa -1 ).…”

“…The relative deformation in the length with the gas pressure of the Fabry-Perot cavity can be described with a linear dependency as in equation (1). Where 𝐿 0 is the without deformation cavity length, Δ𝐿 is the change in cavity length (the deformation), 𝑃 is the pressure and 𝜅 is the pressure-normalized deformation.…”

“…A previous study of the simulated cavity deformation due to pressure was carried out in [1], and its results were used herein to show the difference obtained due to the use of different software. Finally, a new cylindrical design of the cavity was proposed and compared to the design proposed in [1].…”

Measurements of helium permeation in Zerodur glass used for the realisation of quantum pascal

“…To estimate whether Zerodur is more suitable than the ULE glass, different studies are being made, such as the one reported in reference [8]. This evaluation requires the modelling of gas transport dynamics in the material.…”