Shimming and Performance of the Permanent Magnet for NIM-2

You, Qiang; Wang, D.; Xu, Jinxin; Bai, Yang; Li, Z.; Zhang, Z.; Lu, Yunfeng; He, Qing

doi:10.1109/cpem.2018.8500847

Cited by 3 publications

(3 citation statements)

References 5 publications

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“…In (25), the reason why the operations of partial derivative and volume integral can be interchanged is that the magnetization energy change of the coil-suspension system is completely caused by the variations of B m and B c in the vertical direction. The experiment results in [21] showed that the relative change of B m within the ±50 mm vertical range is less than 2 × 10 −4 , so the magnitude of ∂B m /∂z is tiny in the air gap. Besides, the magnitude of B c is much smaller than that of B m .…”

Section: The Effect Of Energized Compensation Coil In the Weighing Phasementioning

confidence: 99%

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The interaction between the magnetized coil-suspension system and the compensation coil in the joule balance

Li¹,

Xu²,

Li³

et al. 2020

Metrologia

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The joule balance is one of the mass traceability devices in the revised International System of Units, and its smooth operation relies on a compensation coil to reduce the effect of the external magnetic field. In this paper, the interaction between the magnetized coil-suspension system and the compensation coil is theoretically analyzed and experimentally verified. First, an additional induced voltage can be detected in the compensation coil when it moves relative to the magnetized coil-suspension system, which will lead to a measurement deviation of several parts in 10 6 in the moving phase. Second, if the excitation current also flows through the compensation coil in the weighing phase, then an additional magnetization force which can not be canceled out by the mass-on and mass-off measurements will be applied on the coil-suspension system. Theoretical analysis indicates that the deviations introduced in the two phases are nearly equivalent, so that the final mass measurement result will not be affected at least on the magnitude of 10 −9 . However, this conclusion can only be verified at 10 −8 level due to the current measurement limitations of the joule balance.

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Section: The Effect Of Energized Compensation Coil In the Weighing Phasementioning

confidence: 99%

“…for I ′ , according to the magnetization principle introduced in section 2, it is related to B m . The experimental results in [21] showed that the magnitude of B m can be approximatively expressed as a quadratic function of z, e.g.…”

Section: The Introduced Deviation In the Moving Phasementioning

confidence: 99%

The interaction between the magnetized coil-suspension system and the compensation coil in the joule balance

Li¹,

Xu²,

Li³

et al. 2020

Metrologia

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“…As shown in figure 11 and equation (43), the magnetic shunt returns part of the magnetic flux, which is then no longer available for the gap. The NIM-2 magnet system used both shimming and a magnetic shunt to remove the B r (z) slope [67]. Since it is difficult to demagnetize the shunt once it is saturated, we recommended to use high-saturation material for the shunt, such as HiperCo50 (saturation magnetic flux density is about 2.4 T).…”

Section: Flattening the Profilementioning

confidence: 99%

The irony of the magnet system for Kibble balances—a review

Schlamminger

2022

Metrologia

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The magnet system is an essential component of the Kibble balance, a device that is used to realize the unit of mass. It is the source of the magnetic flux, and its importance is captured in the geometric factor $Bl$. Ironically, the $Bl$ factor cancels out and does not appear in the final Kibble equation. Nevertheless, care must be taken to design and build the magnet system because the cancellation is perfect only if the $Bl$ is the same in both modes: the weighing and velocity mode. This review provides the knowledge necessary to build a magnetic circuit for the Kibble balance. In addition, this article discusses the design considerations, parameter optimizations, practical adjustments to the finished product, and an assessment of systematic uncertainties associated with the magnet system.

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Preliminary Study on the OMOP Joule Balance

et al. 2020

IEEE Trans. Instrum. Meas.

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Shimming and Performance of the Permanent Magnet for NIM-2

Cited by 3 publications

References 5 publications

The interaction between the magnetized coil-suspension system and the compensation coil in the joule balance

The interaction between the magnetized coil-suspension system and the compensation coil in the joule balance

The irony of the magnet system for Kibble balances—a review

Preliminary Study on the OMOP Joule Balance

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