A new magnet design for future Kibble balances. (4th April 2018)

• Record Type: Journal Article
• Authors: Li, Shisong; Stock, Michael; Schlamminger, Stephan
• Is Part Of: Metrologia. Volume 55:Number 3(2018:Jun.)
• Page Start: 319
• Page End: 325
• Publication Date: 2018-04-04
• Subjects: Kibble balance -- magnetic shielding -- magnetic field -- inductance force; Weights and measures -- Periodicals; Weights and Measures -- Periodicals; 530.805
• DOI: 10.1088/1681-7575/aab2ea
• Languages: English
• ISSNs: 0026-1394

Abstract

Abstract: We propose a new permanent magnet system for Kibble balance experiments, which combines advantages of the magnet designs invented by the National Physical Laboratory (NPL) and by the Bureau International des Poids et Mesures (BIPM). The goal of the proposed magnet system is to minimize the coil-current effect and to optimize the shielding at the same time. In the proposed design, a permanent magnet system with two gaps, each housing a coil, is employed to minimize the coil current effect, by reducing the linear coil-current dependence reported for the single air gap design by at least one order of magnitude. Both air gaps of the magnet are completely surrounded by high-permeability material, and hence the coils are shielded from outside magnetic fields and no magnetic field leaks outside of the magnet system. An example of the new magnet system is given and the analysis shows that the magnetic field in the air gap can be optimized to meet the requirement to be used in Kibble balances.