High-Precision Capacitance Bridge for Dielectric-Constant Gas Thermometry

Fellmuth, B.; Bothe, Harald; Haft, N.; Melcher, J.

doi:10.1109/tim.2010.2099410

Cited by 23 publications

(16 citation statements)

References 7 publications

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“…This was possible by performing comprehensive cross-float experiments. (3) The equipment used for measuring capacitance changes was improved as described in [12,29], which resulted in a relative uncertainty of one part per billion (1 ppb). ( 4) Two new cylindrical measuring capacitors called C1 and C2 were built that have the same design as those used by Luther et al [7].…”

Section: Methodsmentioning

confidence: 99%

Primary thermometry from 2.5 K to 140 K applying dielectric-constant gas thermometry

2017

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Recent thermodynamic temperature measurements at PTB with dielectric-constant gas thermometry were performed up to 140 K. Particular care was taken to check for possible systematic sources of errors by repeating experiments applying two new measuring capacitors and both helium and neon as working gases. The development of a new method for determining the effective compressibility of the new capacitors as a function of temperature has decreased the uncertainty significantly. The combination of the recently obtained results with former values of thermodynamic temperature, corrected using new thermodynamic input data, has yielded a consistent dataset in the range from 2.5 K to 38 K as well as at 84 K, 120 K, 130 K, and 140 K. This dataset is in good agreement with the newest results of acoustic gas thermometry, which has quite different sources of uncertainty compared with dielectricconstant gas thermometry.

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Section: Methodsmentioning

confidence: 99%

Primary thermometry from 2.5 K to 140 K applying dielectric-constant gas thermometry

2017

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“…For balancing the bridge, adjustable in-phase and quadrature currents can be injected. A detailed uncertainty budget for measuring small capacitance changes is presented in [57]. Considering correlations between main terms in the mathematical model, it has been shown that it is possible to measure capacitance changes of at most a few 0.1% with a relative standard uncertainty below one part per million, i.e.…”

Section: The Capacitorsmentioning

confidence: 99%

The Boltzmann project

et al. 2018

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The International Committee for Weights and Measures (CIPM), at its meeting in October 2017, followed the recommendation of the Consultative Committee for Units (CCU) on the redefinition of the kilogram, ampere, kelvin and mole. For the redefinition of the kelvin, the Boltzmann constant will be fixed with the numerical value 1.380 649 × 10−23 J K−1. The relative standard uncertainty to be transferred to the thermodynamic temperature value of the triple point of water will be 3.7 × 10−7, corresponding to an uncertainty in temperature of 0.10 mK, sufficiently low for all practical purposes. With the redefinition of the kelvin, the broad research activities of the temperature community on the determination of the Boltzmann constant have been very successfully completed. In the following, a review of the determinations of the Boltzmann constant k, important for the new definition of the kelvin and performed in the last decade, is given.

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“…However, the recent progress in the ab initio calculation of the polarizability of helium [23] has substantially increased the ultimate accuracy which may potentially be achieved by DCGT. Triggered by this advance, considerable progress has been made in the following areas, all required to facilitate accurate thermodynamic temperature measurement by the method: (i) pressure balances as primary pressure standards [24]; (ii) the instrumentation used for capacitance measurements [25]; and (iii) the characterization of the elastic properties of the materials used for the construction of the capacitors. Through these improvements, most of which have been made at the Physikalisch-Technische Bundesanstalt (PTB), increasingly accurate determinations of thermodynamic temperature in the low-temperature range have been made [26], and the most accurate, to date, determination of the Boltzmann constant at the triple point of water temperature T TPW by this method [27].…”

Section: (I) Acoustic Gas Thermometrymentioning

confidence: 99%