Direct Measurements of the Dielectric Virial Coefficients of<sup>4</sup>He between 3 K and 18 K

White, Margaret P.; Gugan, D.

doi:10.1088/0026-1394/29/1/006

Cited by 27 publications

(20 citation statements)

References 21 publications

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“…[32] and [33] in the temperature range of the present study is used as an estimate of the uncertainty in the value of B ε . For C ε , insufficient literature data exist to determine temperature dependence, so a temperature-independent value is assumed, derived from the average of the only theoretical calculation (at room temperature) [34] and several experimental results (at various temperatures) [35][36][37][38]; the large uncertainty of C ε comes from the standard deviation of these values, yet contributes little to the uncertainty in (T − T 90 ) at the densities used in the present study (see Table 3). The value and uncertainty of A µ come from an interpretation of the calculation of Ref.…”

Section: Procedures For Determining T From a Single Microwave Scanmentioning

confidence: 99%

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

Rourke

2017

Int J Thermophys

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Vous avez des questions?Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.Access and use of this website and the material on it are subject to the Terms and Conditions set forth at NRC microwave refractive index gas thermometry implementation between 24.5 K and 84 K Rourke, P. M. C. https://publications-cnrc.canada.ca/fra/droits L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site Abstract The implementation of microwave refractive index gas thermometry at the National Research Council between 24.5 K and 84 K is reported. A new gas-handling system for accurate control and measurement of experimental gas pressure has been constructed and primary thermometry measurements have been performed using a quasi-spherical copper resonator and helium gas at temperatures corresponding to three defining fixed points of the International Temperature Scale of 1990 (ITS-90). These measurements indicate differences between the thermodynamic temperature T and ITS-90 temperature T 90 of (T − T 90 ) = −0.60 ± 0.56 mK at T 90 = 24.5561 K, (T − T 90 ) = −2.0 ± 1.3 mK at T 90 = 54.3584 K, and (T − T 90 ) = −4.0 ± 2.9 mK at T 90 = 83.8058 K. The present results at T 90 = 24.5561 K and T 90 = 83.8058 K agree with previously reported measurements from other primary thermometry techniques of acoustic gas thermometry and dielectric constant gas thermometry, and the result at T 90 = 54.3584 K provides new information in a temperature region where there is a gap in other recent data sets.Keywords Primary thermometry · Thermodynamic temperature · T − T 90 · Polarizing gas thermometry · Refractive index gas thermometry · RIGT 1 IntroductionThe International Temperature Scale of 1990 (ITS-90) [1, 2] is a practical temperature scale used worldwide to approximate thermodynamic temperature T by ITS-90 temperature T 90 . The ITS-90 was created based on the best thermodynamic temperature measurements available in 1990, mainly those performed using the constant-volume gas thermometry (CVGT) technique.Since 1990, however, new measurements have indicated that T 90 deviates from T over a broad temperature range [3,4]. The most accurate (T − T 90 ) measurements in which R = N A k B is the molar gas constant, N A is the Avogadro constant, k B is the Boltzmann constant, T is the thermodynamic temperature, and B ρ , C ρ and D ρ are density virial coefficients. The presence of T in Eq. 4 is the key to experimentally determining the thermodynamic temperature of the gas.

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Section: Procedures For Determining T From a Single Microwave Scanmentioning

confidence: 99%

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

Rourke

2017

Int J Thermophys

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“…The second and third dielectric virial coefficients of helium, b and c , are approximately a factor of 100 smaller than the second and third density virial coefficients ( B and C ); however, the absolute uncertainties in the two sets of quantities are comparable. The theoretical and experimental results for the second dielectric virial coefficient b for helium were reviewed by White and Gugan [ 8 ] in 1992. They measured b in the range from 3 K to 18 K obtaining the result b = (−0.001 ± 0.004) cm 3 mol −1 .…”

Section: Quantities From Theory and Rmentioning

confidence: 99%

“…This analysis may be considered optimistic because the deformation of conventional capacitors under pressure [ 8 ] is more complex than that assumed here. Capacitors are assembled objects, not simply samples of a uniform material.…”

Section: Quantities To Be Measuredmentioning

confidence: 99%

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Can a pressure standard be based on capacitance measurements?

Moldover

1998

J. Res. Natl. Inst. Stand. Technol.

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We consider the feasibility of basing a pressure standard on measurements of the dielectric constant ϵ and the thermodynamic temperature T of helium near 0 °C. The pressure p of the helium would be calculated from fundamental constants, quantum mechanics, and statistical mechanics. At present, the relative standard uncertainty of the pressure ur(p) would exceed 20 × 10−6, the relative uncertainty of the value of the molar polarizability of helium Aϵ calculated ab initio. If the relativistic corrections to Aϵ were calculated as accurately as the classical value is now known, a capacitance-based pressure standard might attain ur(p) < 6 × 10−6 for pressures near 1 MPa, a result of considerable interest for pressure metrology. One obtains p by eliminating the density from the virial expansions for p and ϵ − 1. If ϵ − 1 were measured with a very stable, 0.5 pF toroidal cross capacitor, the small capacitance and the small values of ϵ − 1 would require state-of-the-art capacitance measurements to achieve a useful pressure standard.

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“…The present results can be applied to many problems in metrology; here we mention a few. Low-density helium is used in primary, constant-volume, gas thermometry [ 1 ]; primary, dielectric-constant gas thermometry [ 2 ]; and in interpolating gas thermometry (required by ITS-90 in the temperature range 3 K to 24.6 K) [ 3 ]. These applications require the extrapolation of measurements to zero pressure.…”

Section: Introductionmentioning

confidence: 99%

Ab initio values of the thermophysical properties of helium as standards

Hurly¹,

Moldover²

2000

J. Res. Natl. Inst. Stand. Technol.

147

136

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Recent quantum mechanical calculations of the interaction energy of pairs of helium atoms are accurate and some include reliable estimates of their uncertainty. We combined these ab initio results with earlier published results to obtain a helium-helium interatomic potential that includes relativistic retardation effects over all ranges of interaction. From this potential, we calculated the thermophysical properties of helium, i.e., the second virial coefficients, the dilute-gas viscosities, and the dilute-gas thermal conductivities of 3He, 4He, and their equimolar mixture from 1 K to 104 K. We also calculated the diffusion and thermal diffusion coefficients of mixtures of 3He and 4He. For the pure fluids, the uncertainties of the calculated values are dominated by the uncertainties of the potential; for the mixtures, the uncertainties of the transport properties also include contributions from approximations in the transport theory. In all cases, the uncertainties are smaller than the corresponding experimental uncertainties; therefore, we recommend the ab initio results be used as standards for calibrating instruments relying on these thermophysical properties. We present the calculated thermophysical properties in easy-to-use tabular form.

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Direct Measurements of the Dielectric Virial Coefficients of⁴He between 3 K and 18 K

Cited by 27 publications

References 21 publications

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

Can a pressure standard be based on capacitance measurements?

Ab initio values of the thermophysical properties of helium as standards

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Direct Measurements of the Dielectric Virial Coefficients of4He between 3 K and 18 K

Cited by 27 publications

References 21 publications

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

Can a pressure standard be based on capacitance measurements?

Ab initio values of the thermophysical properties of helium as standards

Contact Info

Product

Resources

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Direct Measurements of the Dielectric Virial Coefficients of⁴He between 3 K and 18 K