Final report of the supplementary comparison EURAMET.EM-S31 comparison of capacitance and capacitance ratio

Abstract

Within the framework of the supplementary comparison EURAMET.EM-S31, 'Comparison of capacitance and capacitance ratio', five participants (the BIPM, METAS, LNE, PTB, and VSL) inter-compared their capacitance realisations traced to the quantum Hall resistance measured at either ac or dc. The measurands were the capacitance values of three 10 pF standards and one 100 pF standard, and optionally their voltage and frequency dependences. Because the results were not fully satisfying, the circulation was repeated, augmented by a link to the NMIA calculable capacitor. Also two ac-dc resistors were circulated and their frequency dependences were measured in terms of the ac-dc resistance standards involved in the particular capacitance realisations, to allow inter-comparison of these resistance standards. At the end and in any case, a good agreement is achieved within the expanded uncertainties at coverage factor k = 2. Furthermore, the comparison led to new insight regarding the stability and travelling behaviour of the capacitance standards and, by virtue of the link to the NMIA calculable capacitor, to a determination of the von Klitzing constant in agreement with the 2014 CODATA value. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Dual Josephson impedance bridge: towards a universal bridge for impedance metrology

“…Between two DC calibrations the resistance has a linear drift and the DC value can be predicted with an uncertainty smaller than 0.005 μ Ω / Ω. The calculated frequency dependence of the quadrifilar resistance standards has been validated through different inter-comparisons up to a frequency of about 5 kHz [ 5 ], [ 7 ].…”

“…Finally, we note that the value of the 100 pF was obtained at a rms voltage of 10 V with the classical calibration chain and only at 0.3 V with the DJIB calibration chain. No correction was applied for the voltage dependence which is estimated to be smaller than 0.006 μ F/F for this type of capacitor [ 7 ].…”

“…State-of-the art impedance bridges [5][6][7][8][9][10] depend on ratio transformers or inductive voltage dividers (IVDs) to generate voltages whose ratio is accurate and stable. These bridges have been optimized over many years and are now able to compare impedance standards with an accuracy as small as 4 nΩ/Ω for specific impedance ratios and relative phase angles [11].…”

A quantum ampere

“…The corresponding realisation experiments are the calculable inductor [11,12] and the calculable capacitor [13,14]. The calculable capacitor exploits an electrostatic theorem of Thompson and Lampard [15] which reduces the number of relevant mechanical dimensions to be measured to a single length, allowing the calculable capacitor to reach an uncertainty of parts in 10 8 [16].…”