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Optical n(p,T90) Measurement Suite 1: He, Ar, and N2.

Authors :
Egan, Patrick F.
Yang, Yuanchao
Source :
International Journal of Thermophysics. Dec2023, Vol. 44 Issue 12, p1-35. 35p.
Publication Year :
2023

Abstract

An n (p , T 90) measurement suite is reported for the gases helium, argon, and nitrogen. The methodology is optical refractive-index gas metrology, operating at laser wavelength 633 nm and covering the temperature range (293 < T < 433) K and pressures p < 0.5 MPa . The measurement suite produces several things of thermophysical interest. First, the helium dataset deduces the effective compressibility of the apparatus with a relative standard uncertainty of 1.3 × 10 - 4 . Next, the argon dataset determines T - T 90 with a relative standard uncertainty of about 3 μ K · K - 1 . (The implementation is relative primary thermometry; T - T 90 is the difference between thermodynamic temperature and ITS-90.) Finally, the nitrogen dataset estimates the temperature dependence of polarizability within 3.5 % relative standard uncertainty. As a by-product of the nitrogen and argon measurements, values of the second density virial coefficient B ρ (T) are derived with uncertainties smaller than those of previous experiments. More broadly, the work enables conversion of a measured refractivity at known temperature to optical pressure within 3.5 μ Pa · Pa - 1 across the stated range, albeit traceable to the diameter of a piston-gage. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0195928X
Volume :
44
Issue :
12
Database :
Academic Search Index
Journal :
International Journal of Thermophysics
Publication Type :
Academic Journal
Accession number :
174406363
Full Text :
https://doi.org/10.1007/s10765-023-03291-2