Journal Article10.1088/0026-1394/46/5/010
An oscillatory dynamic mode for a watt balance
TL;DR: In this paper, an oscillatory approach to the dynamic or moving mode of a watt balance experiment was proposed as an alternative to the traditional constant velocity approach. But the oscillatory dynamic mode can be used with some of the existing watt balance experiments with the potential to measure γ faster and more precisely than the traditional velocity approach, which is one of the favoured approaches to replacing the present artefact kilogram as it will allow the kilogram to be redefined in terms of the Planck constant.
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Abstract: A watt balance relates mechanical power to electrical power by comparing the gravitational force on a mass with the electromagnetic force on a current-carrying coil in a magnetic field. It is one of the favoured approaches to replacing the present artefact kilogram as it will allow the kilogram to be redefined in terms of the Planck constant. In this paper, we propose an oscillatory approach to the dynamic or moving mode of a watt balance experiment as an alternative to the traditional constant velocity approach. Features of an oscillatory dynamic mode include frequency selection and Fourier analysis to reduce noise due to vibration, the option of larger coil velocities (above 2 mm s−1) and smaller coil movement amplitudes (of order ±1 mm) than the constant velocity approach, and direct measurement at the weighing position of the factor γ relating coil current to the gravitational force on the mass. An oscillatory dynamic mode can be used with some of the existing watt balance experiments with the potential to measure γ faster and more precisely than the constant velocity approach.
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Citations
The watt or Kibble balance: a technique for implementing the new SI definition of the unit of mass.
TL;DR: In this article, the authors describe the theory underlying the Kibble balance and practical techniques required to construct such an instrument to relate a macroscopic physical mass to the Planck constant with an uncertainty, which is achievable at present, in the region of 2 parts in 10^8.
191
A determination of the Planck constant using the LNE Kibble balance in air
Matthieu Thomas,Djamel Ziane,Patrick Pinot,R Karcher,Almazbek Imanaliev,F. Pereira Dos Santos,Sébastien Merlet,François Piquemal,Patrick Espel +8 more
TL;DR: A determination of the Planck constant h using the LNE Kibble balance in air was carried out in the spring of 2017 as discussed by the authors, and substantial improvements since 2014, mainly related to the mass standard, mechanical alignments, voltage measurements and type A evaluation uncertainties, leads to a h value of 6.626 070 41(38) × 10-34 J s, with a relative standard uncertainty of 5.7 × 10−8.
87
Alignment of the NPL Mark II Watt balance.
TL;DR: In this paper, the alignment and correction techniques that have been developed at NPL over many years and are required to minimize the uncertainty of the measurement are collected together and compared for all watt balances, whilst a few are specific to watt balances that employ a conventional beam balance to support a circular coil in a radial magnetic field, such as the NPL Mark II watt balance.
54
The Kibble balance and the kilogram
TL;DR: The Kibble balance was used to realize the unit of mass, the kilogram, by fixing the numerical value of Planck's constant as mentioned in this paper, and the watt balance was renamed to the kibble balance to honor the inventor.
32
Realization of the kilogram using the KRISS Kibble balance
Dongmin Kim,MyeongHyeon Kim,Minky Seo,Byung-Chill Woo,Sungjun Lee,Jong-Ahn Kim,Dong-Hun Chae,Mun Seog Kim,In-Mook Choi,Kwang-Cheol Lee +9 more
TL;DR: The first experiment for kilogram realization at the Korea Research Institute of Standards and Science (KRISS) was reported in this article, where the masses of two artefacts (platinum-iridium and stainless steel) were measured using the KRISS Kibble balance between December 2019 and January 2020 at a pressure between 3 × 10 3 Pa and 4 × 10 7 Pa.
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References
The detection of transient behaviour in environmental vibration for the Watt balance
TL;DR: A two-stage method for the analysis of large numbers of datasets containing measured vibration data using a biorthogonal wavelet technique with Bayesian denoising to detect transient behaviour in environmental vibration data.
Tracing Planck's constant to the kilogram by electromechanical methods
TL;DR: In this paper, the status of the different watt balance experiments is reviewed in detail, and a review of the current state of the art is given for the moving-coil watt balance.
Direct Comparison of Josephson Waveforms Using an AC Quantum Voltmeter
TL;DR: A new method for calibrating ac voltage waveforms based on measuring the difference relative to a synchronously synthesized waveform supplied from a programmable Josephson array is presented and achieves uncertainties at least a factor of ten lower than those from the direct sampling method.
Towards an electronic kilogram: an improved measurement of the Planck constant and electron mass
TL;DR: The electronic kilogram project of NIST has improved the watt balance method to obtain a new determination of the Planck constant h by measuring the ratio of the SI unit of power W to the electrical realization unit W90, based on the conventional values for the Josephson constant KJ−90 and von Klitzing constant RK−90 as discussed by the authors.