Mass determination with the magnetic levitation method—proposal for a new design of electromechanical system

Kajastie, Heikki; Riski, K.; Satrapinski, A.

doi:10.1088/0026-1394/46/3/018

Cited by 4 publications

(2 citation statements)

References 26 publications

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“…The Center for Metrology and Accreditation (MIKES) in Finland continues some of the research, but a comment in [88] reasserted that trapped flux among other things would limit the relative uncertainty at much greater than 10 −8 . A follow up proposal in [89] re-evaluates the earlier system to solve some problems, especially the energy losses in the levitation from tapped flux.…”

Section: Superconducting Magnetic Levitationmentioning

confidence: 99%

History and progress on accurate measurements of the Planck constant

Steiner

2012

Rep. Prog. Phys.

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The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10(-34) J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, N(A). As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 10(8) from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the improved techniques and discoveries in quantum mechanics steadily reduced the uncertainty of h. The central part of this review describes the technical details of the watt balance technique, which is a combination of the mechanical and electronic measurements that now determine h as a direct result, i.e. not requiring measured values of additional fundamental constants. The first technical section describes the basics and some of the common details of many watt balance designs. Next is a review of the ongoing advances at the (currently) seven national metrology institutions where these experiments are pursued. A final summary of the recent h determinations of the last two decades shows how history keeps repeating itself; there is again a question of whether there is a shift in the newest results, albeit at uncertainties that are many orders of magnitude less than the original experiments. The conclusion is that there is room for further development to resolve these differences and find new ideas for a watt balance system with a more universal application. Sin...

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Section: Superconducting Magnetic Levitationmentioning

confidence: 99%

History and progress on accurate measurements of the Planck constant

Steiner

2012

Rep. Prog. Phys.

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“…Electronic mass comparators are usually used for calibrating high accuracy weights all over the world. The repeatability and linearity of electronic mass comparators are good for meeting the calibration requirement of over class F 1 weights, except for mass comparators with a maximum capacity of more than 500 kg [ 1 , 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

Development of a New, High Sensitivity 2000 kg Mechanical Balance

Wang

2017

Sensors

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Mass measurement of more than 500 kg on an electronic mass comparator has no better repeatability and linearity of measurement for meeting the calibration requirement of over class F1 weights from pharmacy and power generation plants. For this purpose, a new 2000 kg mechanical balance was developed by the National Institute of Metrology (NIM). The advantages of measurement of more than 500 kg on a new 2000 kg mechanical balance are introduced in the paper. In order to obtain high measurement uncertainty, four vertical forces of two sides of beam are measured and used as reference for adjustment of the beam position. Laser displacement sensors in the indication system are more effective for decreasing reading errors caused by human vision. To improve the repeatability and sensitivity of the equipment, a synchronous lifting control is designed for synchronously lifting the beam ends along the vertical direction. A counterweight selection system is developed to get any combination of weights in a limited space. The sensitivity of the new mechanical balance for 2000 kg is more than 1.7 parts in 10−4 rad/g. The extended uncertainties for the mechanical balance of 500 kg, 1000 kg and 2000 kg are 0.47 g, 1.8 g and 3.5 g respectively.

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Vacuum Transfer Equipment for M-one

Wang

Cai

et al. 2018

J. Phys.: Conf. Ser.

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Mass determination with the magnetic levitation method—proposal for a new design of electromechanical system

Cited by 4 publications

References 26 publications

History and progress on accurate measurements of the Planck constant

History and progress on accurate measurements of the Planck constant

Development of a New, High Sensitivity 2000 kg Mechanical Balance

Vacuum Transfer Equipment for M-one

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