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1

Establishing and characterizing a permanent magnet system for the prototype of NIS's Kibble balance

Emira Sayed, Shaaban E. R., Rashad M. M., Gelany Shaker A.

Metrology and Measurement Systems

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2023

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Vol. 30, nr 1

3--16

EN

The Kibble balance experiment is used to redefine the kilogram as a unit of mass based on the Planck constant. To demonstrate and understand the basic principle of the Kibble balance, the National Institute of Standards (NIS)-Egypt has constructed a prototype Kibble balance that can measure gram-level masses with 0.01% relative uncertainty. Through the construction of this prototype, the challenges can be studied and addressed to overcome the weaknesses of NIS’s prototype. This study presents the design and construction of the prototype Kibble balance. It also focuses on the design and performance of the magnetic system, which is a crucial element of the Kibble balance. Analytical modeling and finite element analysis were used to evaluate and improve the magnet system. Several other aspects were also discussed, including the yoke’s material and enhancing the magnetic profile within the air gap of the magnet system. Over a vertical distance of 30 mm inside the air gap, the magnetic flux density was found to be 0.3 T, and the uniformity was found to be 8 x 10-5.

2

Josephson Voltage Metrology for Watt Balance Experiments at NIST

Tang Y.-H.

Measurement Automation Monitoring

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2016

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Vol. 62, No. 2

42--45

EN

The Planck constant, h, is one of the seven fundamental constants proposed to redefine the SI. It has been measured by the watt balance experiments since the 1980s. In its early days, the watt balance experiment played a vital role in determining the Josephson constant KJ-90 which was adopted internationally on January 1, 1990. The development of Josephson technology, especially the implementation of the Programmable Josephson Voltage Standard (PJVS) in voltage metrology has improved the uncertainty of voltage measurement in the watt balance experiment by more than two orders of magnitude. The Josephson voltage measurement in the watt balance experiment plays an important role in the proposed SI redefinition based on a set of fundamental constants. This paper will describe a brief history from the original NIST-1 watt balance in 1980s up to the most recent development of the NIST-4 watt balance. We will also discuss the role of voltage metrology in the watt balance experiments and the impact of the SI redefinition to the voltage metrology in the future.

3

Historical and metrological aspects of the development of quantum metrology

Tomilin K. A.

Elektronika : konstrukcje, technologie, zastosowania

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2013

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Vol. 54, nr 6

8-10

PL

W artykule rozważa się kilka z najważniejszych aspektów historycznych i metrologicznych obecnej reformy system miar wynikających z przyjęcia podstawowych stałych h, e oraz k jako jednostek miar (prędkość światła с została wybrana jako jednostka już w 1983). Koncepcja naturalnego systemu jednostek postała z udziałem J. C. Maxwella, J. Stoneya, M. Plancka i innych. Niektóre takie systemy (system Hartree, system Plancka) są szeroko stosowane w fizyce wraz z systemem Gaussa i systemem SI. Należy zauważyć, że system jednostek zaproponowany przez U. Stille'a w 1949, oparty na wyborze stałych c, h, e, k, faktycznie jest podstawą odnowionego systemu SI. Ponadto w artykule wskazuje się na to, że wszystkie stałe wymiarowe są zredukowane do grupy stałych podstawowych, których wzory (zależności) powinny być traktowane jako ich definicje. Pojawiło się wiele mylnych sformułowań w sprawie zredukowania kilku podstawowych stałych fizycznych do kilku innych dzięki wykorzystaniu system Gaussa. Konflikt między systemem jednostek wykorzystywanym w fizyce teoretycznej (system Gaussa, system Heaviside-Lorentza) a Międzynarodowym Układem Jednostek Miar (SI) wynika z przyczyn historycznych, i powinien on zostać przezwyciężony przez odnowę zarówno systemu SIO, jak i systemu Gaussa, zgodnie z wymaganiami nowoczesnej metrologii kwantowej przez wyraźne wykorzystanie stałej struktury subtelnej α w prawach elektrodynamiki.

EN

The paper discusses some of the most important historical and methodological aspects of the current reform in metrology with the adoption of the fundamental constants of h, e and k as units of measurement (velocity of light с was chosen as unit already in 1983). The idea of natural systems of units has arisen from J. C. Maxwell, J. Stoney, M. Planck et al. Some of these systems (Hartree system, Planck system) are widely used in physics along with Gaussian system and practical system SI. It should be noted that the system of units proposed by U.Stille in 1949, based on the choice of the constants c, h, e, k, in fact is underlie of the upgraded SI. The paper also shows that all the dimensional constants are reduced to the primary ones and these formulae should be considered as its definitions. A number of erroneous statements about reducing some of the primary constants to the other ones were caused by using of Gaussian system. The conflict between the system of units used in theoretical physics (Gaussian system, Heaviside-Lorentz system) and the International System of Units (SI) is due to historical reasons, and must be overcome by upgrading both the SI and Gaussian system in accordance with the requirements of modern quantum metrology by explicit allocation of the fine-structure α in electromagnetic laws.