Construction, Measurement, Shimming, and Performance of the NIST-4 Magnet System

The magnet system is one of the key elements of a watt balance. For the new watt balance currently under construction at the National Institute of Standards and Technology, a permanent magnet system was chosen. We describe the detailed construction of the magnet system, first measurements of the fie...

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Bibliographic Details
Published in:arXiv.org 2014-12
Main Authors: Seifert, Frank, Panna, Alireza, Li, Shisong, Han, Bing, Chao, Leon, Cao, Austin, Haddad, Darine, Choi, Heeju, Haley, Lori, Schlamminger, Stephan
Format: Article
Language:English
Subjects:
Electric measuring instruments
Flux density
Magnetic flux
Magnetism
Permanent magnets
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Summary:The magnet system is one of the key elements of a watt balance. For the new watt balance currently under construction at the National Institute of Standards and Technology, a permanent magnet system was chosen. We describe the detailed construction of the magnet system, first measurements of the field profile, and shimming techniques that were used to achieve a flat field profile. The relative change of the radial magnetic flux density is less than \(10^{-4}\) over a range of 5 cm. We further characterize the most important aspects of the magnet and give order of magnitude estimates for several systematic effects that originate from the magnet system.
ISSN:2331-8422
DOI:10.48550/arxiv.1405.1450