Dielectric Constant Gas Thermometry from 4.2 to 27.1 K

Abstract

A new method of high-precision isotherm thermometry has been developed in which the density of helium gas is determined from dielectric constant measurements using the virial expansion of the Clausius-Mossotti equation. The technique is shown to be accurate at the level of -0.3 mK for the range 4.2-27.1 K, with potential for both increased accuracy and increased range. The results confirm that the gas thermometer scale NPL-75 is internally consistent to better than 1 mK, and that Berry's recent values for the second virial coefficient of helium are correct at the levelf 0.05 cm3 mol-'.The results also give a value for the third virial coefficient, C(T) = (5420 f 225)/T cm6 mol-2, and a value of 517.257 f 0.025 x cm3 mol-' for the polarizability of He.

Dielectric-Constant Gas-Thermometry Scale from 2.5 K to 36 K Applying 3He, 4He, and Neon in Different Temperature Ranges

“…The basic idea of DCGT [11], more extensively discussed in [1,2,12], is to replace the density in the equation of state of a gas with the dielectric constant, ε, and to measure it by incorporating a capacitor in the gas bulb. The dielectric constant of an ideal gas is given by the relation ε = ε 0 + α 0 N/V , where ε 0 is the exactly known electric constant, α 0 is the static electric dipole polarizability of the particles, and N/V is the number density, i.e., the equation of state of an ideal gas can be written in the form p = kT (ε − ε 0 )/α 0 .…”

“…Whereas the main goal of the first generation was to check the existing thermodynamic C. Gaiser (B) · B. Fellmuth · N. Haft Physikalisch-Technische Bundesanstalt, Abbestr. [2][3][4][5][6][7][8][9][10][11][12]10587 Berlin, Germany e-mail: christof.gaiser@ptb.de temperature data with an independent method, the second generation was used for an efficiency test to demonstrate that DCGT is capable of determining the Boltzmann constant at the triple point of water (TPW) [4]. Compared with [2,5], the benefit of the extension of the DCGT temperature scale to 36 K presented in this article is threefold.…”

Primary Dielectric-Constant Gas Thermometry in the Range from 2.4 K to 26 K at PTB

“…The basic idea of DCGT [7] is to replace the density in the equation of state of a gas with the dielectric constant, ε, and to measure it by incorporating a capacitor in the gas bulb. The dielectric constant of an ideal gas is given by the relation ε = ε 0 + α 0 N /V , where ε 0 is the exactly known electric constant, α 0 is the static electric dipole polarizability of the atoms, and N /V is the number density, i.e., the equation of state of an ideal gas can be written in the form p = kT (ε − ε 0 )/α 0 .…”

Measurements of the polarizability and of the second and third virial coefficients of4He in the range 4·2-27·1 K

“…Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions [3] which we report briefly here. Our experiments also lead to an accurate value for the polarizability of helium, which appears to have a significant difference from theoretical estimates [4,5].…”